Latest EmDrive tests at Dresden University shows it does not develop any thrust(grenzwissenschaft-aktuell.de)
grenzwissenschaft-aktuell.de
Latest EmDrive tests at Dresden University shows it does not develop any thrust
https://www.grenzwissenschaft-aktuell.de/latest-emdrive-tests-at-dresden-university-shows-impossible-engine-does-not-develop-any-thrust20210321/
313 comments
There is a difference here: cars are built by car mechanics; they know cars inside out --- cars are never designed to drive in reverse. Physicists, on the other hand, didn't invent physics, so they know their current understanding of physics could be wrong.
This idea that we are so sure of everything is pervasive. The kind of people who like science are often the kind of people who crave certainty. And so for them science becomes like a religion, it provides them with a sense of certainty. Consistency. So when they rally against stories like this what they are really doing is reaffirming their own faith in an orderly universe, reaffirming their own faith in their scientific religion. It serves an emotional need. Which is why, paradoxically, their arguments are not alterable through logic.
If you go read what the real experts in a field have to say about the state of knowledge, they are often incredibly humble. They state that there is so much that they do not know. That are so many things that could be wrong. That there are even bigger pictures just beyond their grasp.
Now these reactionless thruster concepts don't look to be doing too well. But I for one am not particularly convinced that mach 's principle is so stupid.
If you go read what the real experts in a field have to say about the state of knowledge, they are often incredibly humble. They state that there is so much that they do not know. That are so many things that could be wrong. That there are even bigger pictures just beyond their grasp.
Now these reactionless thruster concepts don't look to be doing too well. But I for one am not particularly convinced that mach 's principle is so stupid.
This sort of argument is routinely used to dismiss the laws of thermodynamics as merely 'theories' and to then move on to the most outrageous violations of known physical law.
We are pretty sure of what we are sure of and we are pretty sure of what we aren't sure of, impressions notwithstanding. Science is a method, not a set of facts, and it has a built in mechanism to allow greater insights to replace lesser ones. As long as we stick to science we'll one day find the limits of what is knowable.
We are pretty sure of what we are sure of and we are pretty sure of what we aren't sure of, impressions notwithstanding. Science is a method, not a set of facts, and it has a built in mechanism to allow greater insights to replace lesser ones. As long as we stick to science we'll one day find the limits of what is knowable.
I don't think you and GP are in disagreement. The scientific method to let greater insights replace lesser ones is precisely to try and fail at falsifying observations that violate known physical laws.
No physical law is holy for this purpose, although scientists will necessarily have heuristics for what presumed observations they consider good enough to examine closer. Evidently, the EmDrive observations made the threshold! And now we know for sure. Well, close enough, anyway.
No physical law is holy for this purpose, although scientists will necessarily have heuristics for what presumed observations they consider good enough to examine closer. Evidently, the EmDrive observations made the threshold! And now we know for sure. Well, close enough, anyway.
"A theory is the more impressive the greater the simplicity of its premises, the more different kinds of things it relates, and the more extended its area of applicability. Therefore the deep impression that classical thermodynamics made upon me. It is the only physical theory of universal content which I am convinced will never be overthrown, within the framework of applicability of its basic concepts."
(Albert Einstein)
"The law that entropy always increases holds, I think, the supreme position among the laws of Nature. If someone points out to you that your pet theory of the universe is in disagreement with Maxwell's equations — then so much the worse for Maxwell's equations. If it is found to be contradicted by observation — well, these experimentalists do bungle things sometimes. But if your theory is found to be against the second law of thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation."
(Sir Arthur Eddington)
(Albert Einstein)
"The law that entropy always increases holds, I think, the supreme position among the laws of Nature. If someone points out to you that your pet theory of the universe is in disagreement with Maxwell's equations — then so much the worse for Maxwell's equations. If it is found to be contradicted by observation — well, these experimentalists do bungle things sometimes. But if your theory is found to be against the second law of thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation."
(Sir Arthur Eddington)
As plato would say the wall is choosing to hold us up. We may not understand why but it continues this way. At any point this could change. It wasn't until the theory of gravitation that we were able to define our obvervation as a general law.
"Newton's law of universal gravitation is usually stated as that every particle attracts every other particle in the universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers"
This is still a law. We haven't proved this to be true even though it looks to be true.
Laws can get superseeded.
The phlogiston theory is a superseded scientific theory that postulated the existence of a fire-like element called phlogiston (/flɒˈdʒɪstən, floʊ-, -ɒn/)[1][2] contained within combustible bodies and released during combustion
https://en.m.wikipedia.org/wiki/Phlogiston_theory
Another example is Luminiferous Aether
https://en.m.wikipedia.org/wiki/Luminiferous_aether
They are just theories in the end where most are probably correct somewhat.
"Newton's law of universal gravitation is usually stated as that every particle attracts every other particle in the universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers"
This is still a law. We haven't proved this to be true even though it looks to be true.
Laws can get superseeded.
The phlogiston theory is a superseded scientific theory that postulated the existence of a fire-like element called phlogiston (/flɒˈdʒɪstən, floʊ-, -ɒn/)[1][2] contained within combustible bodies and released during combustion
https://en.m.wikipedia.org/wiki/Phlogiston_theory
Another example is Luminiferous Aether
https://en.m.wikipedia.org/wiki/Luminiferous_aether
They are just theories in the end where most are probably correct somewhat.
There is a strong argument to be made that there is no scientific method: https://en.wikipedia.org/wiki/Epistemological_anarchism
Can’t say I agree with the idea, but it’s certainly interesting to consider and at the least should help strengthen or discard a few assumptions!
I think he’s conflating the process with all the other human factors involved. Sure, Galileo maybe did some shady stuff to convince people of his arguments. But that in no way makes a telescope stop working the way it does.
I think he’s conflating the process with all the other human factors involved. Sure, Galileo maybe did some shady stuff to convince people of his arguments. But that in no way makes a telescope stop working the way it does.
If you want to go down a rabbit hole, Nonlinear dynamics is another way to understand science. Many systems operate from a different paradigm of causality; it happens in biology, also common in fields like weather prediction where a large dataset is analyzed for patterns and then hypotheses are driven off the data in the opposite direction.
This has caused some controversy in the scientific community because researchers have been caught using the methodology to "reverse engineer" hypotheses without disclosure, effectively gaming the system.
This has caused some controversy in the scientific community because researchers have been caught using the methodology to "reverse engineer" hypotheses without disclosure, effectively gaming the system.
> it has a built in mechanism to allow greater insights to replace lesser ones. As long as we stick to science
Well you're not sticking to science when you assume any non-explained phenomenon is "impossible" and dismiss it outright.
Science has a long list of "impossibles" that have been proven to be possible. Though of course that list was mostly of phenomenon we couldn't ignore.
Saying "EMdrive is impossible given our current knowledge therefore it is not worth measuring" is tautological!
Electricity and magnetism were seen as separate phenomenon as well and it seems a lot of people would be opposed to even try to put a compass next to a wire!
The only thing I know is that the skeptics don't get the Nobel Prizes.
Good, they measured, and as expected, no thrust. Cool.
Well you're not sticking to science when you assume any non-explained phenomenon is "impossible" and dismiss it outright.
Science has a long list of "impossibles" that have been proven to be possible. Though of course that list was mostly of phenomenon we couldn't ignore.
Saying "EMdrive is impossible given our current knowledge therefore it is not worth measuring" is tautological!
Electricity and magnetism were seen as separate phenomenon as well and it seems a lot of people would be opposed to even try to put a compass next to a wire!
The only thing I know is that the skeptics don't get the Nobel Prizes.
Good, they measured, and as expected, no thrust. Cool.
What makes this article so refreshing and so compelling is that they replicated the NASA results, and then explained and eliminated them. Another "We don't see anything and it's impossible anyway so you guys are idiots or charlatans" would not be helpful. This is.
Just because nothing is 100% knowable ultimately, doesn't mean all unknowns are equal.
Everyone who doesn't want to invest 10000 human lives and a small countries total resources trying to find out if maybe oxidization isn't really exothermic but just somehow always looks that way (is fire hot?), isn't guilty of being incurious or religious.
Come on now.
Everyone who doesn't want to invest 10000 human lives and a small countries total resources trying to find out if maybe oxidization isn't really exothermic but just somehow always looks that way (is fire hot?), isn't guilty of being incurious or religious.
Come on now.
Part of the problem is that it's much easier to come up with a new perpetual motion machine or reactionless drive concept than to prove that it doesn't work. After seeing them all fail, at a certain point people are going to stop paying them any attention. Oh, this time it uses X force in Y configuration? Go away until you have data, we could be more profitably spending time on just about anything else.
It's only difficult because typically it involves a claimed effect right at the limits of what's measurable. A real effect wouldn't have to be barely perceptible, would it?
The person who discovered nitroglycerine didn't somehow find the amount they could make to be right on the edge of detection.
The person who discovered nitroglycerine didn't somehow find the amount they could make to be right on the edge of detection.
> Part of the problem is that it's much easier to come up with a new perpetual motion machine or reactionless drive concept than to prove that it doesn't work.
AKA, the bullshit asymmetry principle
https://en.wikipedia.org/wiki/Brandolini%27s_law
AKA, the bullshit asymmetry principle
https://en.wikipedia.org/wiki/Brandolini%27s_law
I think the arrogance stems from language.
Certainty doesn’t exist, in fact, the only certainty is the certainty that everything we know is wrong at some level of resolution.
Science is the philosophy of being less wrong about nature over time.
Certainty doesn’t exist, in fact, the only certainty is the certainty that everything we know is wrong at some level of resolution.
Science is the philosophy of being less wrong about nature over time.
The framing of "science becomes like a religion" is just projection, nothing else...
For many of us, we just accept that science is, what it is, and its the facts we know at this time. That doesn't mean unwavering absolute faith as implied by saying it's religious, it's just we don't feel the need to have knowledge be anything else other than knowledge that we continuously build upon.
Of course in general, lots of scientists know much more than other scientists and there is always bickering, people who have their identities married to it and so much more - but often times those very same people are often religious too so i question if the religiosity argument really exists or if its merely weaponized by people who fear the comfort of others who are ok with science without faith.
For many of us, we just accept that science is, what it is, and its the facts we know at this time. That doesn't mean unwavering absolute faith as implied by saying it's religious, it's just we don't feel the need to have knowledge be anything else other than knowledge that we continuously build upon.
Of course in general, lots of scientists know much more than other scientists and there is always bickering, people who have their identities married to it and so much more - but often times those very same people are often religious too so i question if the religiosity argument really exists or if its merely weaponized by people who fear the comfort of others who are ok with science without faith.
I'm an atheist. I also have a degree in comp sci a degree in Mathematics and a master's degree in mathematics. I read arxiv daily. I love science, I read constantly. Watching the cutting edge of science from afar is a passion of mine. I like to try to hold a holistic vision of it all in my head - an impossible task, but it keeps me busy.
So, I'm not an enemy of science, I just dislike people harping on about 'impossible' from behind their keyboards when they have little more than a rudimentary knowledge of the subject at hand and too high an opinion of authority.
So, I'm not an enemy of science, I just dislike people harping on about 'impossible' from behind their keyboards when they have little more than a rudimentary knowledge of the subject at hand and too high an opinion of authority.
"God doesn't play dice." and then he kind of did. (Einstein on Quantum-physics)
Impossible is a absolute and science doesn't deal in absolutes. Just in likelihoods and observations.
Impossible is a absolute and science doesn't deal in absolutes. Just in likelihoods and observations.
I appreciate the nuance here. As a person of faith one of the things I love most about both science and religion is the sheer amount of mystery there is in all of it. If there were no mystery in either, science would be dead and faith would be unnecessary. Yet science and religion pretend to be opposed.
Throughout history the greatest clashes between faith and science have occurred when scientific understanding threatens the faith-based assumptions of the age. Imagine Abraham arguing with God over his request to sacrifice Isaac. Instead, he reasoned that God would find another way.
Sometimes our understanding of religion limits our thinking with regard to not just science, but our faith as well.
Throughout history the greatest clashes between faith and science have occurred when scientific understanding threatens the faith-based assumptions of the age. Imagine Abraham arguing with God over his request to sacrifice Isaac. Instead, he reasoned that God would find another way.
Sometimes our understanding of religion limits our thinking with regard to not just science, but our faith as well.
well everything is a people thing because we’re people. What science offers is proof and data that can be reproduced. So no two scientists bickering is not the same as two theologian.
but to those who believe in theology it would appear as such...
> This idea that we are so sure of everything is pervasive
I think this is a common misconception made mostly by people who distrust science as a whole, but not really broadly held. I don't know anyone who understands an area of science at any depth who holds such a view.
The really broad problem is that in science there are things we have very high confidence in, and there are things we have very little confidence in but are the best working models currently - and everything in between. However, communication about where the confidence lies is often poorly done. Many observers who mostly hear about things through the lay press have no good tools to differentiate between "some person with a Ph.D said Y once" and "the vast majority of experts in this field are confident that X".
You are quite right that real experts have a healthy feel for what they don't know - and often humility - but those are often very different things from those that worry people outside the field. All of those same experts could happily give you a list of things they and their colleagues have very good confidence in. It's almost always the right thing to do to accept these and move on.
On the flip side any scientist will tell you there is small but real value at the margins for someone plugging away at a "crazy" theory. They are almost always wrong, but occasionally it turns up something really interesting. The trick is not to involve more people or too much resources, as these are long bets that will mostly fail.
I think this is a common misconception made mostly by people who distrust science as a whole, but not really broadly held. I don't know anyone who understands an area of science at any depth who holds such a view.
The really broad problem is that in science there are things we have very high confidence in, and there are things we have very little confidence in but are the best working models currently - and everything in between. However, communication about where the confidence lies is often poorly done. Many observers who mostly hear about things through the lay press have no good tools to differentiate between "some person with a Ph.D said Y once" and "the vast majority of experts in this field are confident that X".
You are quite right that real experts have a healthy feel for what they don't know - and often humility - but those are often very different things from those that worry people outside the field. All of those same experts could happily give you a list of things they and their colleagues have very good confidence in. It's almost always the right thing to do to accept these and move on.
On the flip side any scientist will tell you there is small but real value at the margins for someone plugging away at a "crazy" theory. They are almost always wrong, but occasionally it turns up something really interesting. The trick is not to involve more people or too much resources, as these are long bets that will mostly fail.
I have always found that people that enjoy science are comfortable with uncertainty. I worked at Bell Labs for 16 years from the mid 1980s through 2000, and I found a lot of people still looking at things that "we all understand" and still wondering about how it really worked.
Science is never 'settled'. There is the current understanding of the art, but that current understanding is not always fulfilling. There are edges and holes in most domains in science where people are poking around wondering how it really works.
A lot of the things I implemented as an engineer (I am not a scientist, but I worked with scientists) were attempts to answer questions. Many of them having to do with "how do we measure this thing, without touching it?" Modeling information and making decisions based on observations against what you were expecting to observe.
Science is never 'settled'. There is the current understanding of the art, but that current understanding is not always fulfilling. There are edges and holes in most domains in science where people are poking around wondering how it really works.
A lot of the things I implemented as an engineer (I am not a scientist, but I worked with scientists) were attempts to answer questions. Many of them having to do with "how do we measure this thing, without touching it?" Modeling information and making decisions based on observations against what you were expecting to observe.
Scientism. The deification of scientists and our current models.
Which is ironic as we know our models are wrong somehow as we can't mesh Quantum mechanics and general relativity. There is clearly some undiscovered idea or principal.
Science is about the process not about the body of knowledge we amassed. Science is about doing experiments to poke at the gaps of our knowledge. Not to like the Ancient Greeks debate our way to truth or worse declare something false based clearly on our flawed understanding.
Which is ironic as we know our models are wrong somehow as we can't mesh Quantum mechanics and general relativity. There is clearly some undiscovered idea or principal.
Science is about the process not about the body of knowledge we amassed. Science is about doing experiments to poke at the gaps of our knowledge. Not to like the Ancient Greeks debate our way to truth or worse declare something false based clearly on our flawed understanding.
Do you really believe this?
Celebrity scientists aren't deified... in fact, they have a tough life because people assume they're all knowing. Look at our man Neil DeGrasse who called a Bull a Cow because where he lives in NYC everything is a cow and he got ripped by other scientists for being stupid.
There is no universality to people period... i'm not sure why you feel its important to label some as "scientism" when there is no such thing as "scientism" with any universality.
Celebrity scientists aren't deified... in fact, they have a tough life because people assume they're all knowing. Look at our man Neil DeGrasse who called a Bull a Cow because where he lives in NYC everything is a cow and he got ripped by other scientists for being stupid.
There is no universality to people period... i'm not sure why you feel its important to label some as "scientism" when there is no such thing as "scientism" with any universality.
Feynman said something like true science is not believing anything you hear and something you have to experience. If you believe anything without doing the work then you’re cargo culting science which is deifying it.
Scientists aren't deified because people assume they're all knowing?
As for scientism, there's a lot of people in this thread who essentially said "We could have known it wouldn't work by basic application of conservation of momentum". Or some other principal held to the standard of absolute truth.
Our knowledge of the world is faulty and incomplete. All scientific knowledge is subject to tweaking or replacement based on experimental evidence. Not the other way around.
We have models and guesses of how the world works, we don't have its source code.
As for scientism, there's a lot of people in this thread who essentially said "We could have known it wouldn't work by basic application of conservation of momentum". Or some other principal held to the standard of absolute truth.
Our knowledge of the world is faulty and incomplete. All scientific knowledge is subject to tweaking or replacement based on experimental evidence. Not the other way around.
We have models and guesses of how the world works, we don't have its source code.
Actually the whole point why this EM drive is interesting actually is that the measurements contradicted conservation of momentum. Otherwise having a small effect not contradicting any established physics is basically worthless.
Sure, but if the contradiction bore out, then what's false (at least in some edge cases) is established physics not the experiment result.
The strength of the established physics just means that there is an extremely high chance that the EM drive is experimental error, especially with the small effect size, rather than something novel.
The strength of the established physics just means that there is an extremely high chance that the EM drive is experimental error, especially with the small effect size, rather than something novel.
> The kind of people who like science are often the kind of people who crave certainty.
Just to clarify - are you implying scientists crave certainty, or non-scientists who enjoy reading about science crave certainty?
The life scientists I know are the people in my life who are the most comfortable with uncertainty, or at least can recognize how uncertain the world can be. Perhaps they crave quantifying the uncertainty? But they certainly understand, respect, and live with uncertainty.
Just to clarify - are you implying scientists crave certainty, or non-scientists who enjoy reading about science crave certainty?
The life scientists I know are the people in my life who are the most comfortable with uncertainty, or at least can recognize how uncertain the world can be. Perhaps they crave quantifying the uncertainty? But they certainly understand, respect, and live with uncertainty.
I took it to mean the fans of science who pile into forums like HN with expressive enthusiastic skepticism, the kind of people who think experimental physics is like working on a car.
> Just to clarify - are you implying scientists crave certainty, or non-scientists who enjoy reading about science crave certainty?
Mostly the latter, but also the former to some degree. The scientists holding the status quo are often the most resistant to a paradigm shift.
Mostly the latter, but also the former to some degree. The scientists holding the status quo are often the most resistant to a paradigm shift.
> If you go read what the real experts in a field have to say...
If you go to read what the real experts in the field have to say then you would learn that not a single one of them thought that the EM Drive had even the slightest chance of being true.
In fact all the publications and work on EM Drive strictly avoided the real experts (physicists). They were all engineering journals. A paper that claims experimental evidence that overturns all physical theories from Newton onwards that's very telling isn't it?
If you go to read what the real experts in the field have to say then you would learn that not a single one of them thought that the EM Drive had even the slightest chance of being true.
In fact all the publications and work on EM Drive strictly avoided the real experts (physicists). They were all engineering journals. A paper that claims experimental evidence that overturns all physical theories from Newton onwards that's very telling isn't it?
Thank you for more eloquently expressing a sentiment that I have harboured for some time. After quoting the relevant Cave Johnson quote from PORTAL 2 so many times... it clicked and I came to the realisation that there is only one way to “do science” you “throw it at the wall and see if it sticks”.
At a fundamental level, you must throw your results at the wall of publication and see if they stick, the only way science sticks is when it can be replicated by others. It remain on the wall!
When people’s refutation of things like the em-drive is simply “this can’t work” my response is “prove it” not because I believe, but because “can’t work” just isn’t science, science is done by proving that something “does not work”. That means for something like the em-Drive you prove it doesn’t do what it claims, you prove it by replication and better measurement... and you learn how to build things better, learn how to measure better and that’s the value of these efforts! Or you prove it by detailed non destructive analysis of the experiment apparatus and prove your work by detailed physical simulation, publishing your code to prove you didn’t make any mistakes yourself! You cannot just give the answer you must show your work if you expect to go around calling what you do “science”. Providing such proof is not a waste, or bad science, it is the very essence of science itself.
At a fundamental level, you must throw your results at the wall of publication and see if they stick, the only way science sticks is when it can be replicated by others. It remain on the wall!
When people’s refutation of things like the em-drive is simply “this can’t work” my response is “prove it” not because I believe, but because “can’t work” just isn’t science, science is done by proving that something “does not work”. That means for something like the em-Drive you prove it doesn’t do what it claims, you prove it by replication and better measurement... and you learn how to build things better, learn how to measure better and that’s the value of these efforts! Or you prove it by detailed non destructive analysis of the experiment apparatus and prove your work by detailed physical simulation, publishing your code to prove you didn’t make any mistakes yourself! You cannot just give the answer you must show your work if you expect to go around calling what you do “science”. Providing such proof is not a waste, or bad science, it is the very essence of science itself.
You are missing a very important part of how science is done: science starts with a hypothesis, the refutation or confirmation of that hypothesis is done by experiment. Plenty of science has been locked into the theoretical phase for decades before experimental verification could be obtained.
If all we did was experiments we'd surely find some interesting stuff but without theory to guide where to do the next set of experiments science would be very inefficient. It's the closing of the loop that powers this tremendous progress you see from the renaissance to today.
Without that we'd be stuck in alchemy, astrology and other pseudo sciences.
If all we did was experiments we'd surely find some interesting stuff but without theory to guide where to do the next set of experiments science would be very inefficient. It's the closing of the loop that powers this tremendous progress you see from the renaissance to today.
Without that we'd be stuck in alchemy, astrology and other pseudo sciences.
Science must find a balance between extremes in how experimental resources are invested:
Extreme “Exploitation” Bias: “For maximally economical progress, experimental physics must strictly stay within the hard boundaries established by theoretical frameworks.”
Extreme “Exploration” Bias: “For maximally fundamental progress, experimental physics must question all theoretical assumptions and boundaries with extreme suspicion.”
It makes sense to diversify the kind of experimental investments we make along this risk/reward or exploration/exploitation spectrum. There are unique dangers if we weight too heavily on either extreme.
Extreme “Exploitation” Bias: “For maximally economical progress, experimental physics must strictly stay within the hard boundaries established by theoretical frameworks.”
Extreme “Exploration” Bias: “For maximally fundamental progress, experimental physics must question all theoretical assumptions and boundaries with extreme suspicion.”
It makes sense to diversify the kind of experimental investments we make along this risk/reward or exploration/exploitation spectrum. There are unique dangers if we weight too heavily on either extreme.
> science starts with a hypothesis
No, science starts with an observation which is not explained by the prevailing theory. Then you form a hypothesis, etc.
At least in principle. The reality of science is a lot messier.
No, science starts with an observation which is not explained by the prevailing theory. Then you form a hypothesis, etc.
At least in principle. The reality of science is a lot messier.
I think there's one more step that goes a bit earlier in the process. Before an observation is made, there needs to be a choice on what experiments are done. Typically, those measurements will be done with one of two goals. The first is to measure a free parameter in the theory that isn't well-constrained by existing experiments. (e.g. "According to Maxwell's equations, the speed of light should be constant. Let's measure that constant value." [0]) The second is to find an unintuitive prediction from current models, then measure what happens in those circumstances. (e.g. "According to special relativity, passage of time should vary based on velocity. That's weird. Let's measure and see if it is the case." [1])
The purpose of these is to narrow down which experiments are being performed, trying to choose experiments that will try their hardest to break an existing theory.
[0] https://en.wikipedia.org/wiki/Speed_of_light#Time_of_flight_...
[1] https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experim... (This article currently has an incorrect edit made yesterday. It seems to be based on a mistaken assumption that the rotating earth is a stationary reference frame. The opening paragraph should read "were consistent" rather than "were not consistent".)
The purpose of these is to narrow down which experiments are being performed, trying to choose experiments that will try their hardest to break an existing theory.
[0] https://en.wikipedia.org/wiki/Speed_of_light#Time_of_flight_...
[1] https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experim... (This article currently has an incorrect edit made yesterday. It seems to be based on a mistaken assumption that the rotating earth is a stationary reference frame. The opening paragraph should read "were consistent" rather than "were not consistent".)
So much for theoretical physics then. Or Einstein's 'gedanken experimenten'.
> they know their current understanding of physics could be wrong.
Sure, we do know!
And we know how to recognise when someone masters current literature (a.k.a. factual knowledge) and proposes a breaktrough in a yet uncovered field, and when someone is speaking out of his ... nothing!
If you prefer a non-car analogy: we all do know that a hundred consecutive heads is possible, still you are not going to bet your week pay on it, even if you were promised 2^100 weeks of pay in return.
Sure, we do know!
And we know how to recognise when someone masters current literature (a.k.a. factual knowledge) and proposes a breaktrough in a yet uncovered field, and when someone is speaking out of his ... nothing!
If you prefer a non-car analogy: we all do know that a hundred consecutive heads is possible, still you are not going to bet your week pay on it, even if you were promised 2^100 weeks of pay in return.
There are plenty of cases where someone who doesn't understand the underlying theory has contributed due to the outsider effect or just pure luck. The hype, and the swindling are not ok, but when an organization like NASA thinks they maybe successfully reproduced an experiment that invalidates a law of nature you have to keep trying. Sure I'm hoping for new science, always, because that is more fun, but mostly you need to know for sure what the experimental error was so that you don't repeat it in an experiment whose result you aren't as skeptical of.
>There are plenty of cases where someone who doesn't understand the underlying theory has contributed due to the outsider effect or just pure luck.
There are far more such cases where the outsider was wrong, so many more of these, that using the extremely rare event to claim this may be one is simply terrible reasoning. It is far more likely that this is yet another crackpot pushing nonsense.
No outside has found a breakthrough that for decades (the length the EmDrive people have been making noise) was discarded. In fact, when an outsider finds something useful or novel, for a long time now the science community nearly immediately understands and embraces it.
This is the opposite of that.
There are far more such cases where the outsider was wrong, so many more of these, that using the extremely rare event to claim this may be one is simply terrible reasoning. It is far more likely that this is yet another crackpot pushing nonsense.
No outside has found a breakthrough that for decades (the length the EmDrive people have been making noise) was discarded. In fact, when an outsider finds something useful or novel, for a long time now the science community nearly immediately understands and embraces it.
This is the opposite of that.
Can you name some of those cases?
> There are plenty of cases where someone who doesn't understand the underlying theory has contributed due to the outsider effect or just pure luck
Are you talking about anyone who was born in the last 100 years?
Are you talking about anyone who was born in the last 100 years?
A low number of dollars spent to put to bed an idea that would have upended physics is a fairly cost effective play in the risk to reward game. That’s what it comes down too.
Negative results are good. Utter quackery is not good. But hard data from experiment is usually not quackery. Even if the whole thing stands outside the established paradigm. I’d argue we could stand a bit more of it, in this age of funding bandwagons and careerism.
Negative results are good. Utter quackery is not good. But hard data from experiment is usually not quackery. Even if the whole thing stands outside the established paradigm. I’d argue we could stand a bit more of it, in this age of funding bandwagons and careerism.
> Utter quackery is not good.
That's the OP's point. The EmDrive is utter quackery. It cannot exist because it necessarily violates the laws of thermodynamics. Anything that disproves those will literally undermine the entire foundation of what we understand about the universe. It would be directly comparable to discovering that the earth is flat.
That's the OP's point. The EmDrive is utter quackery. It cannot exist because it necessarily violates the laws of thermodynamics. Anything that disproves those will literally undermine the entire foundation of what we understand about the universe. It would be directly comparable to discovering that the earth is flat.
We already know the laws of thermodynamics has exceptions. In very small systems, the entropy of a system fluctuates randomly - up and down. A light ray traveling over extremely long distances will have its energy reduced through red shifting, and that energy doesn't "go" anywhere, it is destroyed. In both of these regimes, over extremely small scales and extremely large scales, there are exceptions carved out of the laws of thermodynamics.
We know for certain that our understanding of physics is incomplete. General relativity (as formulated) is certainly wrong, because it precludes the possibility of small things existing; and yet they do. Quantum mechanics (as formulated) is certainly wrong, because it precludes the possibility of curved spacetime, and yet we know spacetime is curved.
There is, of course, a minuscule possibility that the emdrive actually works. It almost certainly doesn't. Ballpark one in a thousand. But we can't exclude the possibility that it works, based on the principle that the the laws of thermodynamics, which already has two exceptions, cannot have a third exception.
There's big talk about humanity traveling to other stars, colonizing other star systems, colonizing the galaxy and so forth. For this to happen, we would have to be wrong about physics. There's simply not any way to do it by building on the foundation of what we understand about the universe. So investing in low probability speculative ideas like emdrive is still necessary, even though for any given idea, there are lots of nines that say it won't work.
We know for certain that our understanding of physics is incomplete. General relativity (as formulated) is certainly wrong, because it precludes the possibility of small things existing; and yet they do. Quantum mechanics (as formulated) is certainly wrong, because it precludes the possibility of curved spacetime, and yet we know spacetime is curved.
There is, of course, a minuscule possibility that the emdrive actually works. It almost certainly doesn't. Ballpark one in a thousand. But we can't exclude the possibility that it works, based on the principle that the the laws of thermodynamics, which already has two exceptions, cannot have a third exception.
There's big talk about humanity traveling to other stars, colonizing other star systems, colonizing the galaxy and so forth. For this to happen, we would have to be wrong about physics. There's simply not any way to do it by building on the foundation of what we understand about the universe. So investing in low probability speculative ideas like emdrive is still necessary, even though for any given idea, there are lots of nines that say it won't work.
>the laws of thermodynamics has exceptions
No, they don't. The "laws" you learn in high school are large scale approximations to the actual rules, which is codified in stat mech.
It's like claiming solids are not solid because atoms... Of course physicists know all this.
>General relativity (as formulated) is certainly wrong, because it precludes the possibility of small things existing
Having worked on GR stuff for a long time, this is news. GR most certainly allows any size thing to exist - it's a continuous theory.
>Quantum mechanics (as formulated) is certainly wrong, because it precludes the possibility of curved spacetime
No, it does not. QM in curved spacetime is so old and well understood it has a Wikipedia page [1] - from which you can start digging back into the literature.
You should really google such claims when making them to be sure you understand what you're claiming.
[1] https://en.wikipedia.org/wiki/Quantum_field_theory_in_curved...
No, they don't. The "laws" you learn in high school are large scale approximations to the actual rules, which is codified in stat mech.
It's like claiming solids are not solid because atoms... Of course physicists know all this.
>General relativity (as formulated) is certainly wrong, because it precludes the possibility of small things existing
Having worked on GR stuff for a long time, this is news. GR most certainly allows any size thing to exist - it's a continuous theory.
>Quantum mechanics (as formulated) is certainly wrong, because it precludes the possibility of curved spacetime
No, it does not. QM in curved spacetime is so old and well understood it has a Wikipedia page [1] - from which you can start digging back into the literature.
You should really google such claims when making them to be sure you understand what you're claiming.
[1] https://en.wikipedia.org/wiki/Quantum_field_theory_in_curved...
What an exciting time we live in, where links between quantum mechanics, thermodynamics, and GR May finally be emerging in physics! What will the final ramifications be? Hopefully something new comes of it.
If there are cases where conservation laws break down, or physical principles constrain one another in unforeseen ways, and they can be accessed at human scale, what an exciting thing! I’d guess you mostly feel this way too if I have not yet imposed any quackery on you, and suppose where we diverge is I do not see the harm in exploration as far out as the experimenter can dream to go. —Even if there is no theory for it. I know, the horror!
Do I think it will work? Well heck no. But that does not mean I wish the attempt to be quashed like I’m the inquisition. On the contrary, I bid them good luck. And if they do have good luck, they better have some results that are easily duplicated. I hope they do overthrow the foundations of physics. Why not? The earth will still possess curvature, and all the extant physics will still be as approximately right, and beautiful, as it was yesterday.
The guy had an experiment, his explanation for the results were utter quackery. I don't think the people at NASA expected his explanation was the right one, but they didn't have one so they replicated. MIT had an explanation of the results that was not due to thermal effects, and wasn't the originator's explanation. It didn't upend thermodynamics. The problem wasn't people exploring a tricky experiment, it was people buying in to a specific explanation of the experiment prematurely.
[deleted]
Lemaitre?
> we all do know that a hundred consecutive heads is possible, still you are not going to bet your week pay on it, even if you were promised 2^100 weeks of pay in return
The expected reward is just one-week's pay --- you have to offer better than that with all the uncertainty ;)
What if the reward is potentially infinite amount of money? If the investigation proved our current understanding of physics wrong, that could lead to historic breakthroughs in natural science.
Better yet, we don't know what the odd is. It might only need 32 consecutive heads.
The expected reward is just one-week's pay --- you have to offer better than that with all the uncertainty ;)
What if the reward is potentially infinite amount of money? If the investigation proved our current understanding of physics wrong, that could lead to historic breakthroughs in natural science.
Better yet, we don't know what the odd is. It might only need 32 consecutive heads.
I'd be very curious how it's possible to have 2^100 of anything :)
Oh, it's just 1024^10, a bit more than 10^30, or 10 million moles.
A water molecule contains 18 nucleons, thus a mole of water weighs 18 grams. 10 million moles of water are 180 cubic metres: an Olympic pools contains an order of magnitude more moles than that! ;-)
Sure, I hope nobody is paid so poorly that 2^100 times its week salary exists!
A water molecule contains 18 nucleons, thus a mole of water weighs 18 grams. 10 million moles of water are 180 cubic metres: an Olympic pools contains an order of magnitude more moles than that! ;-)
Sure, I hope nobody is paid so poorly that 2^100 times its week salary exists!
There are certainly people who aren't paid anything.
> Physicists, on the other hand, didn't invent physics, so they know their current understanding of physics could be wrong.
They also know they have experimented extensively over the region this effect claims to exist, and have found nothing of the kind for well over a century, and that if the EmDrive did what some claimed, it would violate literally thousands to millions of experiments already conducted.
Claiming physicists don't know everything about possible physics does not imply they don't know a tremendous amount about the places they have extensive experimental and theoretical agreement. Those places are not likely to ever change.
They also know they have experimented extensively over the region this effect claims to exist, and have found nothing of the kind for well over a century, and that if the EmDrive did what some claimed, it would violate literally thousands to millions of experiments already conducted.
Claiming physicists don't know everything about possible physics does not imply they don't know a tremendous amount about the places they have extensive experimental and theoretical agreement. Those places are not likely to ever change.
This whole thing has been obviously dumb for a number of reasons not even related to physics. You could almost use it as a good litmus test for who should be running a company, or working at important positions in government.
> Physicists, on the other hand, didn't invent physics, so they know their current understanding of physics could be wrong.
Technically, yes. but not in the sense that the word "wrong" is generally used. Existing measurements confirm that the current theories are mostly correct to high degree of accuracy, and over a lot of measurements, in a wide range of circumstances.
Current understanding may be proven _incomplete_, but it won't be superseded by something completely different that contradicts those measurements. That would be a non-starter, but it's what people think of when they hear "x is wrong".
e.g. Newtonian mechanics is "wrong" or "incomplete", but it gives very good answers for everyday circumstances. Just not for very small or very fast.
The best essay on this subject is "The Relativity of Wrong", Asimov, 1989
https://chem.tufts.edu/answersinscience/relativityofwrong.ht...
Technically, yes. but not in the sense that the word "wrong" is generally used. Existing measurements confirm that the current theories are mostly correct to high degree of accuracy, and over a lot of measurements, in a wide range of circumstances.
Current understanding may be proven _incomplete_, but it won't be superseded by something completely different that contradicts those measurements. That would be a non-starter, but it's what people think of when they hear "x is wrong".
e.g. Newtonian mechanics is "wrong" or "incomplete", but it gives very good answers for everyday circumstances. Just not for very small or very fast.
The best essay on this subject is "The Relativity of Wrong", Asimov, 1989
https://chem.tufts.edu/answersinscience/relativityofwrong.ht...
I agree that on this point the analogy is weak. But it describes the ignorance of all those hyping it up well.
People are generally aware that if someone is presenting a perpetuum mobile they are wrong. Free energy doesn't exist. The fact that you can't have free momentum is just as strong (and has been known longer), yet less widely intuited.
Let me give you an analogy though:
Let's say someone proposes a water base perpetuum mobile like this:
https://en.wikipedia.org/wiki/Perpetual_motion#/media/File:W...
It only works if you place the machine under a massive waterfall though. Now this would be very difficult to refute experimentally, because you have to account for all possible interactions in the waterfall.
That's what the EM Drive is. A perpetuual motion machine built in such a way that there's a lot of energy going around and it's hard to eliminate all spurious interactions.
People are generally aware that if someone is presenting a perpetuum mobile they are wrong. Free energy doesn't exist. The fact that you can't have free momentum is just as strong (and has been known longer), yet less widely intuited.
Let me give you an analogy though:
Let's say someone proposes a water base perpetuum mobile like this:
https://en.wikipedia.org/wiki/Perpetual_motion#/media/File:W...
It only works if you place the machine under a massive waterfall though. Now this would be very difficult to refute experimentally, because you have to account for all possible interactions in the waterfall.
That's what the EM Drive is. A perpetuual motion machine built in such a way that there's a lot of energy going around and it's hard to eliminate all spurious interactions.
It's tough to know absolutely everything about a complex dynamic system, even if it's built by humans. Take the economy, for instance. Invented by humans, made up of humans and human technologies and concepts, and yet people only have vague ideas about how to control it.
Or take computers for that matter. People designed and built them from scratch. Someone had to design and lay out the transistors on the CPU, and presumably they know everything about how to do that. And yet we are currently trying to figure whether there's an ordering to switching the transistors on and off that would imbue the CPU with human-level intelligence. There are plenty of people who know computers inside and out, yet there are still questions that need answers. We have a whole discipline called Computer Science that performs experiments on computers for the purpose of answering these questions.
Or take computers for that matter. People designed and built them from scratch. Someone had to design and lay out the transistors on the CPU, and presumably they know everything about how to do that. And yet we are currently trying to figure whether there's an ordering to switching the transistors on and off that would imbue the CPU with human-level intelligence. There are plenty of people who know computers inside and out, yet there are still questions that need answers. We have a whole discipline called Computer Science that performs experiments on computers for the purpose of answering these questions.
I really don't think cars are designed by the same people who end up fixing them - ease of repair really doesn't seem to be a big factor in lots of designs.
Ease of repair has largely been replaced by lack of need of repair. Cars, especially IC engines, are so much more reliable today that repair is relatively rare. Engine rebuilds are almost unheard of on small cars. Transmissions regularly outlast the chasis. Even tires rarely get flats. People now expect to drive many tens or even a hundred thousand miles without engine failure, on no more maintenance than an occasional oil change.
Ease of repair is a factor, but there are other factors. Safety and Fuel Economy (Aerodynamics and mass) are more important than ease of repair so many things to make it easy to repair just get tossed out.
The design of a car is obviously limited by fundamental aspects of physics which are outside of the control of car manufacturers. For example, car manufacturers didn't invent combustion, aerodynamics, etc.
Physicists don’t even build things anymore. They just plug in math. No wonder they’re divorced from reality.
> cars are never designed to drive in reverse.
that's just plain wrong, friend.
that's just plain wrong, friend.
On the other hand, this is the sort of attitude that would make an informed skeptic reject the theoretical possibility for nuclear power, two weeks before the first nuclear bombs were used in war.
It took a team of physicists four years to disprove this result. Did they do it just to prove a point, or because they didn't understand the car analogy? No, professional scientists are rarely that callous with their time.
There was a slim possibility that our understanding of physics was wrong, and now we know for sure that this was not an instance of that.
But everything that's really interesting happens at the edges. No groundbreaking scientific result, ever, has happened by rejecting out of hand unlikely observations that violate established theory.
It took a team of physicists four years to disprove this result. Did they do it just to prove a point, or because they didn't understand the car analogy? No, professional scientists are rarely that callous with their time.
There was a slim possibility that our understanding of physics was wrong, and now we know for sure that this was not an instance of that.
But everything that's really interesting happens at the edges. No groundbreaking scientific result, ever, has happened by rejecting out of hand unlikely observations that violate established theory.
These weren't rejected out of hand - from the very first results there were ripe questions being asked (i.e., why did it take so long to measure thrust, and how were they controlling for thermal expansion, see even here on HN, quoted elsewhere in this thread - https://news.ycombinator.com/item?id=12962579 )
You're absolutely correct that building better testing to disprove it completely is a good thing to do, just to remove the extreme unlikelihood that one of the most fundamental laws in thermodynamics are incorrect, but extreme skepticism is definitely warranted when the claim is so huge, and people are able to find realistic flaws (sufficiently realistic as to be proven to be correct) that would explain it entirely.
You're absolutely correct that building better testing to disprove it completely is a good thing to do, just to remove the extreme unlikelihood that one of the most fundamental laws in thermodynamics are incorrect, but extreme skepticism is definitely warranted when the claim is so huge, and people are able to find realistic flaws (sufficiently realistic as to be proven to be correct) that would explain it entirely.
I'm not arguing against the points you are making, but they are subtly different from what OP implied. It's hard to make specific claims against a vague analogy that just seems to embody a mindset, but that's what I'm trying to do. And it's not a strawman even if it would happen to miss OP's intent; you see this mindset everywhere.
My point was that OP appears to would have rejected this hypothesis out of hand, and that this approach that would be wrong if everyone that matters did it. Obviously there were people who mattered who did not, as the experiment demonstrates.
A posteriori it's difficult to put numbers on it, but I'd say this experiment was worth doing even if your heuristics put it at a 0.1% chance of succeeding. Obviously that's not the case for Mad Morty's 1000th garage-built perpetual motion machine, but multiple physicists obviously evaluated this hypothesis as less shitty than that.
All in all we would probably agree if we could just zero in on our key points, so I probably shouldn't have spent four paragraphs on this.
My point was that OP appears to would have rejected this hypothesis out of hand, and that this approach that would be wrong if everyone that matters did it. Obviously there were people who mattered who did not, as the experiment demonstrates.
A posteriori it's difficult to put numbers on it, but I'd say this experiment was worth doing even if your heuristics put it at a 0.1% chance of succeeding. Obviously that's not the case for Mad Morty's 1000th garage-built perpetual motion machine, but multiple physicists obviously evaluated this hypothesis as less shitty than that.
All in all we would probably agree if we could just zero in on our key points, so I probably shouldn't have spent four paragraphs on this.
? A nuclear power plant was built before the bombs. It's main purpose was to generate bomb material, but they definitely showed the principle worked and powered a lightbulb with it.
I was making a rhetorical point, but it works if you switch out 'theoretically' with 'actually', and 'two weeks before' with 'while the first nuclear reactor was supercritical in Chicago'.
I'm pretty certain that the practicality of a nuclear chain reaction wasn't widely accepted in December of 1942, even though fission was first demonstrated by Meitner and Hahn three years before.
I'm pretty certain that the practicality of a nuclear chain reaction wasn't widely accepted in December of 1942, even though fission was first demonstrated by Meitner and Hahn three years before.
Not 2 weeks before, but the parent comment applies if you switch out "two weeks" with "a couple years", right?
https://www.atomicarchive.com/history/manhattan-project/p1s2...
https://www.atomicarchive.com/history/manhattan-project/p1s2...
I was under the impression that atomic weapons and reactors were both based on known physics, not the overturning of it.
If it wasn't considered theoretically possible, what do you make of Einstein's famous letter?
If it wasn't considered theoretically possible, what do you make of Einstein's famous letter?
The bomb really wasn't known. Some people speculated that it may work, some people were sure that it couldn't.
I've finished https://www.goodreads.com/book/show/170428.Now_It_Can_Be_Tol... last week, and from what I understand, a lot of people didn't think that bomb is a possibility (for example, the Germans weren't really sure), and even when the Manhattan project was running several years, the scientists still weren't sure that the bomb will work as expected. There was a lot of variables in play, and for example, materials for the bombs weren't available for testing in large enough qualities.
One of the concerns, from what I understand as a layman, was that a critical amount of material will blow itself up too early, so that most of the material won't be part of the explosion. This was solved, I think, by some kind of neutron reflectors, or something*.
There are few chapters about how part of the Manhattan project was capturing scientists from France, Italy and Germany. When they captured them, their housing was bugged and there are transcripts from that time in the book. When the bombs were dropped, they generally couldn't believe that it really worked.
* One of the transcripts shows, that the Germans didn't think of this, and when they thought about the bomb, the thought about basically overloaded nuclear reactor, which would be big, heavy and impractical for use as a bomb.
I've finished https://www.goodreads.com/book/show/170428.Now_It_Can_Be_Tol... last week, and from what I understand, a lot of people didn't think that bomb is a possibility (for example, the Germans weren't really sure), and even when the Manhattan project was running several years, the scientists still weren't sure that the bomb will work as expected. There was a lot of variables in play, and for example, materials for the bombs weren't available for testing in large enough qualities.
One of the concerns, from what I understand as a layman, was that a critical amount of material will blow itself up too early, so that most of the material won't be part of the explosion. This was solved, I think, by some kind of neutron reflectors, or something*.
There are few chapters about how part of the Manhattan project was capturing scientists from France, Italy and Germany. When they captured them, their housing was bugged and there are transcripts from that time in the book. When the bombs were dropped, they generally couldn't believe that it really worked.
* One of the transcripts shows, that the Germans didn't think of this, and when they thought about the bomb, the thought about basically overloaded nuclear reactor, which would be big, heavy and impractical for use as a bomb.
All the time on HN I read posts saying how we should celebrate negative results. Here we have a negative result.
Why not celebrate it?
Why not celebrate it?
Claim: banging your head against the wall makes you smarter.
Experimenters: that sounds amazing! So we tried. We can report that all test subjects reported a massive headache. Unfortunately none seemed to get significantly smarter.
You: a negative result, well done! Time to celebrate!
And now I hope you will accept my apologies for exaggerating to the point of being rude, all in reply to your entirely reasonable question.
I guess my point is this. There has to be a cutoff where a claim is too obviously incorrect and testing is simply not useful any more. But the natural cutoff point depends enormously on perspective. Are you a car mechanic, a rally driver, or a complete layman? And as the latter, who do you trust?
My original comment was written to highlight the frustrating perspective of the car mechanic. But an interested layperson (or a non-expert handing out grant money) might have the more difficult time.
Experimenters: that sounds amazing! So we tried. We can report that all test subjects reported a massive headache. Unfortunately none seemed to get significantly smarter.
You: a negative result, well done! Time to celebrate!
And now I hope you will accept my apologies for exaggerating to the point of being rude, all in reply to your entirely reasonable question.
I guess my point is this. There has to be a cutoff where a claim is too obviously incorrect and testing is simply not useful any more. But the natural cutoff point depends enormously on perspective. Are you a car mechanic, a rally driver, or a complete layman? And as the latter, who do you trust?
My original comment was written to highlight the frustrating perspective of the car mechanic. But an interested layperson (or a non-expert handing out grant money) might have the more difficult time.
> I guess my point is this. There has to be a cutoff
> where a claim is too obviously incorrect and testing
> is simply not useful any more.
Emphatically not. There is an important difference between 'outlandish' and 'in flagrant contradiction with billions of experimental results [0]'.
I am not saying that the difference is always easy to spot, but I think that you cannot deny that it exists.
[0] For a crude estimate, see 'number of collisions per second' at https://home.cern/resources/faqs/facts-and-figures-about-lhc . And those people are looking really hard for possible violations of the law of conservation of momentum: in this context it is called 'missing transverse energy' and it is a key method in the search for new physics.
I am not saying that the difference is always easy to spot, but I think that you cannot deny that it exists.
[0] For a crude estimate, see 'number of collisions per second' at https://home.cern/resources/faqs/facts-and-figures-about-lhc . And those people are looking really hard for possible violations of the law of conservation of momentum: in this context it is called 'missing transverse energy' and it is a key method in the search for new physics.
But it seems to me that in the earlier EmDrive experiments, there were forces found that were not explained satisfactorily. Now, through better experimental controls, all of these have been accounted for. That sounds like valuable research to me.
Good point. It should both make future experiments more accurate and also debunk similar claims more easily.
Science isn't a bunch of scientists saying "we doubt it'll work"—science is a bunch of scientists experimentally proving it doesn't work.
The people funding the scientists decide what's worth testing. In this case, the possible benefit vastly outweighed the cost of testing.
To fix the head-to-wall metaphor: in some experiments, subjects who banged their heads against the wall reported being cured of all mental illness. However more rigorous tests showed this remarkable effect was actually a placebo caused by the subjects believing they were involved in making history.
Science isn't a bunch of scientists saying "we doubt it'll work"—science is a bunch of scientists experimentally proving it doesn't work.
The people funding the scientists decide what's worth testing. In this case, the possible benefit vastly outweighed the cost of testing.
To fix the head-to-wall metaphor: in some experiments, subjects who banged their heads against the wall reported being cured of all mental illness. However more rigorous tests showed this remarkable effect was actually a placebo caused by the subjects believing they were involved in making history.
hello, speaking as a diesel engine mechanic, this is exactly what modern emissions controls have sadly become.
professional drivers (truckers) want to cut out all the emissions control systems because "older trucks get better mileage!" On the face of the issue this seeems to be true, but even after cutting everything out and switching back to low-grade diesel all you've done is create a smoke and soot belching mess from the 1960's. Why is this?
Two reasons: older trucks got great mileage because there was less traffic congestion and fewer weigh station stops, and the national maximum speed limit law in 1973 made sure trucks drove a speed that got great mileage.
professional drivers (truckers) want to cut out all the emissions control systems because "older trucks get better mileage!" On the face of the issue this seeems to be true, but even after cutting everything out and switching back to low-grade diesel all you've done is create a smoke and soot belching mess from the 1960's. Why is this?
Two reasons: older trucks got great mileage because there was less traffic congestion and fewer weigh station stops, and the national maximum speed limit law in 1973 made sure trucks drove a speed that got great mileage.
Interesting analogy, but the pessimistic view does not bring any progress. The optimistic view may often be wrong, but when it is actually right, it makes our civilization progress.
Not so long ago, the experts knew and said it was impossible to land and reuse a rocket.
Not so long ago, the experts knew and said it was impossible to land and reuse a rocket.
What you call the "pessimistic view" might be very enthusiastic about projects that are orders of magnitude more likely to work. So in my opinion, the relevant axis is not optimistic vs. pessimistic, but informed vs. uninformed.
Can an outsider with no knowledge of the field make a chance discovery? It's theoretically possible, and we might want to support undirected experimentation for the one in a billion chance that something might work. But we should take those probabilities into account when allocating our collective resources.
Can an outsider with no knowledge of the field make a chance discovery? It's theoretically possible, and we might want to support undirected experimentation for the one in a billion chance that something might work. But we should take those probabilities into account when allocating our collective resources.
So tell me, how do we calculate probability for yet unknown phenomen? Which is more 'probable' to be correct - string theory or loop quantum gravity?
If I want to investigate einstein rosen bridges, whats the probability I am wasting my time?
If I want to investigate einstein rosen bridges, whats the probability I am wasting my time?
Usually you look at the volume of experimental evidence that directly contradicts it. In this case there’s quite a lot.
This this this. Sooooo much. This always was flying spaghetti monster level unlikely. People simply do not understand how tightly constrained things like this are by existing evidence. And almost uniquely so.
When experimentalists announced they had discovered super-luminal neutrinos, everybody reacted exactly like all the amateurs here are saying we should: Explore potential theoretical ramifications while being aware that it's most likely measurement error and encourage further study until we're sure.
Not so for the EMDrive. Why? Because the idea that using nothing but electromagnetism you can violate this foundational property of every physical theory since Newton (_including_ electromagnetism) means that somehow your electromagnetic device, while operating well within the range of millions of other experiments out there, somehow triggered behaviour fundamentally different from electromagnetism. Different from the type of theory that electromagnetism is. Different from the type of theory that every physical theory ever found to describe reality is. And yet this phenomenon that is utterly _different_ than anything else we have ever seen went completely unnoticed in the millions of em sensitive experiments performed by everyone from undergrads to international labs over the last two centuries.
In the strictest sense it's not logically impossible that this could happen. But only in the sense that it's not logically impossible that the flying spaghetti monster is manipulating every scientific experiment performed to hide itself.
When experimentalists announced they had discovered super-luminal neutrinos, everybody reacted exactly like all the amateurs here are saying we should: Explore potential theoretical ramifications while being aware that it's most likely measurement error and encourage further study until we're sure.
Not so for the EMDrive. Why? Because the idea that using nothing but electromagnetism you can violate this foundational property of every physical theory since Newton (_including_ electromagnetism) means that somehow your electromagnetic device, while operating well within the range of millions of other experiments out there, somehow triggered behaviour fundamentally different from electromagnetism. Different from the type of theory that electromagnetism is. Different from the type of theory that every physical theory ever found to describe reality is. And yet this phenomenon that is utterly _different_ than anything else we have ever seen went completely unnoticed in the millions of em sensitive experiments performed by everyone from undergrads to international labs over the last two centuries.
In the strictest sense it's not logically impossible that this could happen. But only in the sense that it's not logically impossible that the flying spaghetti monster is manipulating every scientific experiment performed to hide itself.
We had rockets that landed with Apollo. We had rockets that were reused with the shuttle.
Who said it was impossible to combine them? And "impractically expensive and counterproductive" doesn't count.
Who said it was impossible to combine them? And "impractically expensive and counterproductive" doesn't count.
> We had rockets that landed with Apollo
Correction: We had rockets that could land on the moon. There was no orbital-class rocket that could launch from Earth and land back at launch site (or further downrange). The difference in gravity + lack of atmosphere is a big factor.
It is like saying that the Apollo ascent module could get to orbit and therefore we can clearly make practical SSTO vehicles.
> We had rockets that were reused with the shuttle.
If you consider throwing away the massive external tank and external SRBs (without which it couldn't fly) and completely re-building the three engines after every flight.
Correction: We had rockets that could land on the moon. There was no orbital-class rocket that could launch from Earth and land back at launch site (or further downrange). The difference in gravity + lack of atmosphere is a big factor.
It is like saying that the Apollo ascent module could get to orbit and therefore we can clearly make practical SSTO vehicles.
> We had rockets that were reused with the shuttle.
If you consider throwing away the massive external tank and external SRBs (without which it couldn't fly) and completely re-building the three engines after every flight.
> It is like saying that the Apollo ascent module could get to orbit and therefore we can clearly make practical SSTO vehicles.
If we didn't have to worry about fuel, we could. "put in enough fuel so it can land" is not a hard problem to solve with earth rockets, it just costs payload.
> completely re-building the three engines after every flight
It's complicated but the level of rebuilding was driven more by very high standards than it actually being necessary to make it launchable.
If we didn't have to worry about fuel, we could. "put in enough fuel so it can land" is not a hard problem to solve with earth rockets, it just costs payload.
> completely re-building the three engines after every flight
It's complicated but the level of rebuilding was driven more by very high standards than it actually being necessary to make it launchable.
> "put in enough fuel so it can land" is not a hard problem to solve with earth rockets, it just costs payload.
I am pretty sure that the convex optimization algorithms used by SpaceX's landing systems are a very recent invention (http://larsblackmore.com/publications.htm). As for worrying about fuel, what's the point of a rocket if it cannot take any payload?
I am pretty sure that the convex optimization algorithms used by SpaceX's landing systems are a very recent invention (http://larsblackmore.com/publications.htm). As for worrying about fuel, what's the point of a rocket if it cannot take any payload?
Doubtful. Who ever said that about rockets?
There was huge skepticism in the industry that landing and re-using first stage boosters was viable. Tony Bruno of ULA in 1015, 7 months before SpaceX recoverd their first booster, on their plan to recover the engine module of Vulcan:
"Our concept for reusability is inside that mathematics and realizes that maybe reusability does not start with entire stages,"
It's not that they thought it was impossible to do at all, but they thought the weight requirement of fuel, landing legs, heat protection, etc would be so high that it would eat up too much of your payload capacity.
"Our concept for reusability is inside that mathematics and realizes that maybe reusability does not start with entire stages,"
It's not that they thought it was impossible to do at all, but they thought the weight requirement of fuel, landing legs, heat protection, etc would be so high that it would eat up too much of your payload capacity.
Scepticism is way too often confused with negativity, pessimism or even outright hostility.
It's also often overlooked that a solution might not be the best fit for everyone. Just like it's best for the Falcon 9 to discard the second stage.
It's also often overlooked that a solution might not be the best fit for everyone. Just like it's best for the Falcon 9 to discard the second stage.
Right, the reason ULA can't adapt Vulcan to land the first stage propulsively is it can't throttle down low enough. It's only barely possible with the F9, and that's because it uses a cluster of smaller engines and happens to have one in the middle.
That wasn't a design choice driven by reusability, originally SpaceX were aiming to recover the stage using parachutes. The original plan was a falcon with a cluster of 5 engines in a ring. Using a cluster of smaller engines was for two reasons. First because they didn't have the resources to develop a new larger engine. Second they wanted to mass produce the engines to get production efficiencies and a bigger run of smaller engines worked better for that.
It just worked out serendipitously that this lead to a design that was very well suited to adapting for propulsive landings. If they'd developed F5 first instead, they wouldn't have been able to land it because without a single centre engine they would need to use at least 2 engines to land, and the thrust would be way too high. Even with a design with a centre engine, the Merlin would be too powerful for the weight of an F5.
This isn't a criticism, it's just the way things worked out.
That wasn't a design choice driven by reusability, originally SpaceX were aiming to recover the stage using parachutes. The original plan was a falcon with a cluster of 5 engines in a ring. Using a cluster of smaller engines was for two reasons. First because they didn't have the resources to develop a new larger engine. Second they wanted to mass produce the engines to get production efficiencies and a bigger run of smaller engines worked better for that.
It just worked out serendipitously that this lead to a design that was very well suited to adapting for propulsive landings. If they'd developed F5 first instead, they wouldn't have been able to land it because without a single centre engine they would need to use at least 2 engines to land, and the thrust would be way too high. Even with a design with a centre engine, the Merlin would be too powerful for the weight of an F5.
This isn't a criticism, it's just the way things worked out.
No. The optimistic view incurs opportunity cost: instead of attempting the impossible, something useful could have been done instead.
I see one little caveat with this argument, though: is it always known in advance that something really is impossible?
As long as there's enough resources to go around to pay 8 figure meme-value dollar amounts for digital assets without intrinsic value, I think there's no harm in spending a fraction of that on possibly fruitless research.
As long as there's enough resources to go around to pay 8 figure meme-value dollar amounts for digital assets without intrinsic value, I think there's no harm in spending a fraction of that on possibly fruitless research.
> 8 figure meme-value dollar amounts for digital assets without intrinsic value
The problem is the people who do that are hell bent against letting the government tax them to fund such research, so our research resources are immensely more constrained than they could be.
The problem is the people who do that are hell bent against letting the government tax them to fund such research, so our research resources are immensely more constrained than they could be.
This reminded me of the extended range with reversed ski box for tesla. https://electrek.co/2020/03/24/tesla-model-3-roof-rack-box-r...
Ironically, this serves as an excellent refutation of the above analogy’s goal (to scoff at EMDrive experiments):
* Imagine telling a mechanic that mounting a ski box on your car with the fat/blunt end pointed forward seems to improve fuel economy vs being mounted the other way.
* The mechanic believes it’s absurd to claim you can improve fuel economy from a change that increases wind drag, so therefore your experiment is wrong since it seems to contradict established theory — case closed.
* Imagine that you more carefully measure, and find that it still seems to work surprisingly well (though also mysteriously reducing braking and cornering performance)!
* The mechanic still denies the result (which is unfair), and questions your test methodology and demands replications of the experiment (which is fair).
* Imagine someone else tries to replicate the experiment with a differently shaped ski box (i.e. not an airfoil, or with the airfoil shape vertically inverted), and fails to reproduce your results.
* The mechanic community concludes that the original result was obviously just experimental error, since the latter failure to replicate aligns with current theoretical consensus of what should happen.
In a similar way, early pioneers experimenting with winged aircraft design were laughed/scoffed at endlessly by established scientists/engineers of the era, ridiculed and crackpots wasting valuable time and resources.
The aerodynamics of the airfoil (which also explains the above ski box phenomenon) is an extremely non-obvious emergent effect, and even to this day is not as fully understood as most people probably assume.
* Imagine telling a mechanic that mounting a ski box on your car with the fat/blunt end pointed forward seems to improve fuel economy vs being mounted the other way.
* The mechanic believes it’s absurd to claim you can improve fuel economy from a change that increases wind drag, so therefore your experiment is wrong since it seems to contradict established theory — case closed.
* Imagine that you more carefully measure, and find that it still seems to work surprisingly well (though also mysteriously reducing braking and cornering performance)!
* The mechanic still denies the result (which is unfair), and questions your test methodology and demands replications of the experiment (which is fair).
* Imagine someone else tries to replicate the experiment with a differently shaped ski box (i.e. not an airfoil, or with the airfoil shape vertically inverted), and fails to reproduce your results.
* The mechanic community concludes that the original result was obviously just experimental error, since the latter failure to replicate aligns with current theoretical consensus of what should happen.
In a similar way, early pioneers experimenting with winged aircraft design were laughed/scoffed at endlessly by established scientists/engineers of the era, ridiculed and crackpots wasting valuable time and resources.
The aerodynamics of the airfoil (which also explains the above ski box phenomenon) is an extremely non-obvious emergent effect, and even to this day is not as fully understood as most people probably assume.
It was an aerodynamics engineer who suggested flipping the box around.
Have 'reverse car races' ever been a thing outside of NL?
https://youtu.be/a59KyXhk74w?t=177
https://youtu.be/a59KyXhk74w?t=177
For a bit of context: a brand called DAF ("van Doornes Automobiel Fabriek") came up with a very clever drive system, called variomatic. It is still in use today under CVVT in Honda vehicles. DAF had an unfair reputation as a 'womans car' because you didn't have to shift gears at all, nor was there a finicky automatic gearbox to maintain, just two pulleys and a belt for each rear wheel. Which gave it insane acceleration as well because the torque convertor gave maximum torque at the lowest speeds ramping down the torque gradually and continuously as speed increased.
One peculiar aspect of this drive system is that it allows your car to go as fast in reverse as it does forward! Of course the Dutch could not let this go without setting up a race around that theme, which was wildly popular in the past.
Since dafjes have an 'unfair advantage' you also got a secondary class, with other car brands, this is a video of that race.
Here are the DAFs:
https://www.youtube.com/watch?v=zoh8i0jfpTo
That video really hurts to look at by the way, the casual destruction of such a large number of what would be very special classics today is grating, especially that pretty 55 coupe is one that I'd love to keep around.
One peculiar aspect of this drive system is that it allows your car to go as fast in reverse as it does forward! Of course the Dutch could not let this go without setting up a race around that theme, which was wildly popular in the past.
Since dafjes have an 'unfair advantage' you also got a secondary class, with other car brands, this is a video of that race.
Here are the DAFs:
https://www.youtube.com/watch?v=zoh8i0jfpTo
That video really hurts to look at by the way, the casual destruction of such a large number of what would be very special classics today is grating, especially that pretty 55 coupe is one that I'd love to keep around.
Creative destruction :-)
Fair enough, it is a bit creative, but only really the first time. They go for twice the original new price now!
If it makes you feel any better : I have very fond memories of these shows ( I was very small still ).
My mom had the real thing :)
She'd outpull Porsches just for fun...
She'd outpull Porsches just for fun...
In reverse?
Also, thank you for finally making sense of a childhood memory of a Jacobse & Van Es photo where they sit in a car, with the caption "200 km/u? Dat rijden wij al in z'n achteruit!"
Also, thank you for finally making sense of a childhood memory of a Jacobse & Van Es photo where they sit in a car, with the caption "200 km/u? Dat rijden wij al in z'n achteruit!"
Indian Man Drives Car Backwards On Busy Highways:
https://www.youtube.com/watch?v=aox_4-JNed8
=> so it may be faster indeed... :-)
=> so it may be faster indeed... :-)
Awesome if you like crashes :-D
Starts at 35:10 min
Actually, in the US, sometimes demolition derby cars run in reverse, because they get to protect the radiators that way.
I don't know, but that video obviously needs a bit of Yakety Sax:
https://tubedubber.com/?q=a59KyXhk74w:MK6TXMsvgQg:0:100:174:...
https://tubedubber.com/?q=a59KyXhk74w:MK6TXMsvgQg:0:100:174:...
This seems a lost battle. Every EM Drive discussion I have seen has been dominated by non-scientists pontificating about how we don't know anything, and our theories might be wrong, and we should keep an open mind ...
Re the airflow point, many cars are indeed MORE aerodynamic than normal in reverse, particularly hatchbacks.
It's best to have a smooth, progressive tail to minimise flow separation at the rear of the car (think of an airfoil shape - quite blunt at the front, thin at the back).
Hatchbacks often have very flat rear ends compared to the front which usually has a more progressive slope. A famous example is the Austin Allegro, but it's actually quite common.
It's best to have a smooth, progressive tail to minimise flow separation at the rear of the car (think of an airfoil shape - quite blunt at the front, thin at the back).
Hatchbacks often have very flat rear ends compared to the front which usually has a more progressive slope. A famous example is the Austin Allegro, but it's actually quite common.
I have zero doubt that this whole thing could have been applied to the first airplane, or to a thousand other firsts.
[deleted]
That's an elaborate "I told you so"!
There is a blockchain-applied-to-anything-other-than-finance metaphor hidden in this truly sublime analogy.
reminds me of the hyperloop bubble a bit
also for all the knowledgeable people hurt by naive enthusiasm.. I guess a healthy dose of cynicism is to find a way to benefit from this and then reuse them for your better thought out projects
also for all the knowledgeable people hurt by naive enthusiasm.. I guess a healthy dose of cynicism is to find a way to benefit from this and then reuse them for your better thought out projects
kungito(1)
What you do is short them on the stock market. Put your money where your mouth is!
How exactly could this be done reliably? With shorts you have to commit to a timeframe for not only finding evidence to reject the claim but also for the news to break and convince other investors.
Meanwhile you can be targetted by financial actors that play your positions on the stock market, at times even disregarding the atual company behind it. Further you have to mind monetary policy. If faith in the stock suffers compared to other stock but the overall market just goes up and up, your shorts have a problem again.
Personally, I have no informed opinion on EmDrive, but I have been very pesimistic about companies in the past and I am about some right now. Still, I do not think that shorts are anything appropirate for me. I'd much rather buy competitior's stock than burn myself with shorts or waste hundreds of hours getting into the financial market that I could also use to create value in my actual job/profession
Meanwhile you can be targetted by financial actors that play your positions on the stock market, at times even disregarding the atual company behind it. Further you have to mind monetary policy. If faith in the stock suffers compared to other stock but the overall market just goes up and up, your shorts have a problem again.
Personally, I have no informed opinion on EmDrive, but I have been very pesimistic about companies in the past and I am about some right now. Still, I do not think that shorts are anything appropirate for me. I'd much rather buy competitior's stock than burn myself with shorts or waste hundreds of hours getting into the financial market that I could also use to create value in my actual job/profession
How would that work, in the analogy?
Short the individual researchers? Research projects? Short private funding?
Scams like EmDrive (but there are countless others – "save the planet with X") may be amusing, as long as it's on someone else's dime. Live and let live.
But the minute they manage to convince enough people, whether by virtue or shady marketing, it becomes a political problem. And then it's your problem too, through taxation and "too big to fail", no matter your position. Shorting on the stock market gets you only so far, and only for entities that actually exist on the stock market.
Short the individual researchers? Research projects? Short private funding?
Scams like EmDrive (but there are countless others – "save the planet with X") may be amusing, as long as it's on someone else's dime. Live and let live.
But the minute they manage to convince enough people, whether by virtue or shady marketing, it becomes a political problem. And then it's your problem too, through taxation and "too big to fail", no matter your position. Shorting on the stock market gets you only so far, and only for entities that actually exist on the stock market.
The stock market currently thinks Gamestop is the most revolutionary company in the world.
An irrational market can stay irrational for longer than you can stay solvent
ala, he'd rather put is mouth where our eyeballs are.
This analogy would have also worked for a quantum computer proposal at the beginning of the 20th century.
Not really, the objection would have been it was completely impractical, and it was (and borderline still is).
When the facts change, opinions can change.
The objection to the EmDrive is that is that it makes no sense, which is much less likely to change.
When the facts change, opinions can change.
The objection to the EmDrive is that is that it makes no sense, which is much less likely to change.
> Now suppose you are a car mechanic in all this .. the disadvantages in air flow
Not sure a mechanic is better than anyone with understanding of car dynamics, but the "air flow" argument is the key to this.
Who are the experts on emDrive tech, and what principle does the emDrive violate? If you can't say, then you are indeed a pessimist.
Not sure a mechanic is better than anyone with understanding of car dynamics, but the "air flow" argument is the key to this.
Who are the experts on emDrive tech, and what principle does the emDrive violate? If you can't say, then you are indeed a pessimist.
> the "air flow" argument is the key to this.
I would point out that cars have gears, but then someone would say that in the US they do not, and I would have to explain that that is not the case, actually, and it would all get very tiring very quickly.
> Who are the experts on emDrive tech, and what principle does the emDrive violate?
A physicist would point out that momentum is conserved, so nothing can start moving without something else moving in the opposite direction, but then someone would point out that cars seem to be able to do just that, and then I would point out this big round thing underneath a car, and it would all get very tiring very quickly.
I would point out that cars have gears, but then someone would say that in the US they do not, and I would have to explain that that is not the case, actually, and it would all get very tiring very quickly.
> Who are the experts on emDrive tech, and what principle does the emDrive violate?
A physicist would point out that momentum is conserved, so nothing can start moving without something else moving in the opposite direction, but then someone would point out that cars seem to be able to do just that, and then I would point out this big round thing underneath a car, and it would all get very tiring very quickly.
> I would point out that cars have gears
How does that relate to airflow?
How does that relate to airflow?
It doesn’t have anything to do with airflow but does with whether or not cars are faster in reverse.
But it's a response to me pointing out air-flow is relevant (key).
He is saying that air flow is not more important than gearing, but if he were to raise it he’d end up in a never ending series of replies debating the details but missing the point.
Sure, but I don't agree gearing is in the same category of the specific thing I mentioned. Would he also end up in a never-ending series of replies wrt airflow too? If not, it has nothing to do with my point, if so why change the topic..
Literally in the first paragraph on Wikipedia:
It is purported to generate thrust by reflecting microwaves internally in the device, in violation of the law of conservation of momentum and other laws of physics.
https://en.wikipedia.org/wiki/EmDrive
Extraordinary evidence is required for extraordinary claims. Any hint of evidence at all is required for idiot claims before waisting people's time.
It is purported to generate thrust by reflecting microwaves internally in the device, in violation of the law of conservation of momentum and other laws of physics.
https://en.wikipedia.org/wiki/EmDrive
Extraordinary evidence is required for extraordinary claims. Any hint of evidence at all is required for idiot claims before waisting people's time.
For everyone that’s expressing a view like “what a waste of time”, consider this. This hypothesis was by a respected scientist. The experiments have been done by lots of labs. There has been a reasonable position the skeptics have taken throughout. It still has taken a very long time of a bunch of smart people on how to build an experiment to rule these kinds of things out. That means theories have tighter bounds. Technology has been improved in the area which can have knock on beneficial educational and technological effects, etc. Being able to quickly and efficiently rule out hypotheses is a hallmark of the area that science shines in. Being able to say “no, definitely not” with very good certainty is a useful thing to this disciplines toolbelt. From that perspective it’s a pure win and worth any distraction on the scale of all human investment globally.
Yeah this is great - they have made an advance in how they can make measurements. There will be many more reaction-less thruster concepts to analyse in the future. Now we have a much better idea how to test them effectively.
These measurement techniques are useful in other areas, too. Less error means more confidence in results for experimental physicists and potentially one less source of error to care about.
Or maybe finally learn mechanics 101 - what the conservation of momentum is. The kind of stuff we expect to understand from smart 16 year olds.
This is the physics equivalent of someone writing a brute-force recursive SAT solver and wondering why it takes so long. Perhaps we don't measure time correctly? What if mirrors are an illusion? We mustn't stop advancing the field!
This is the physics equivalent of someone writing a brute-force recursive SAT solver and wondering why it takes so long. Perhaps we don't measure time correctly? What if mirrors are an illusion? We mustn't stop advancing the field!
This argument reminds me of the historical arguments made against heliocentrism vs geocentrism. Just because we have widespread belief of one thing to be true does not mean we should blindly accept it and not test things that appear to oppose it.
In my opinion, the tests that have happened with the EmDrive are exactly what _should_ happen to make sure that our knowledge is strong and that we do keep advancing the field.
In my opinion, the tests that have happened with the EmDrive are exactly what _should_ happen to make sure that our knowledge is strong and that we do keep advancing the field.
"Velocities add" is also mechanics 101, and turned out to be incorrect at sufficiently large speeds. I think we have to go to Noether's theorem to show why we should be so sure the EM drive doesn't work: EM drive proponents must either tell us where the momentum goes, or explain why space isn't symmetric under translation.
(Actually, fun side note, in a gravitational field, space isn't symmetric under translation. IIRC, this was the original problem that caused Noether to prove her famous theorem. She found that while there was still a conserved quantity of a sort due to "translations" in space and time, it wasn't just the energy-momentum tensor, but also depended on the gravitational field. In any case, the EM drive is supposed to work in flat space, so that shouldn't become an issue.)
(Actually, fun side note, in a gravitational field, space isn't symmetric under translation. IIRC, this was the original problem that caused Noether to prove her famous theorem. She found that while there was still a conserved quantity of a sort due to "translations" in space and time, it wasn't just the energy-momentum tensor, but also depended on the gravitational field. In any case, the EM drive is supposed to work in flat space, so that shouldn't become an issue.)
Yeah, those morons at NASA'S Advanced Propulsion Physics Laboratory sure have no idea what is a good use of their time.
This fellow (Eagleworks guy) was told in no uncertain terms by his PhD thesis committee at Rice that this was a bad idea and forced to rewrite his thesis. He clearly doesn’t know when to take a hint.
Yes there are commonly clever people that know how to play organizational ladders with minimum amount of work in every sufficiently large organization. Also a fair amount of "morons".
Arthur C Clark has addressed this general point in his first law:
“ When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.”
“ When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.”
I have MSc in mathematics, I can follow the idea of conservation of momentum. I just know a little more than you and understand that things are not so simple.
So far I think it has been handled well. Let's just hope this doesn't end up like cold fusion where no amount of proof that it doesn't work can't make it go away and conspiracy theories keep growing.
[deleted]
Just to be clear, for most anyone with low-thrust measurement experience, thermal drift had been suspect nr 1 from the moment Eagleworks published their work. Here is a comment I made back at that time:
https://news.ycombinator.com/item?id=12962579
But then, nobody had Tajmar's perseverance; kudos to his team!
https://news.ycombinator.com/item?id=12962579
But then, nobody had Tajmar's perseverance; kudos to his team!
Lol at the lone reply you received. You called it and that's what you got. I hope we can learn to look at all points from more perspectives in the future.
I mean, most people didn't believe that this was real. It's not like he was the lone voice saying "nah this is surely bollocks...".
That wasn't clear at the time.
This post shows how hard it was for scientists to prove it's bollocks. And the above comment shows how the general population doesn't want their hopes dashed.
This post shows how hard it was for scientists to prove it's bollocks. And the above comment shows how the general population doesn't want their hopes dashed.
It really was clear at the time. Even then people pointed out that the measurements didn't behave in the way you'd expect if it actually worked (e.g. thrust didn't correlate with power).
There were plenty of people saying "But imagine if it did work! We could get to other stars in a few years!" but you always get crazy optimists that ignore all the evidence with stuff like this (c.f. solar roadways).
There were plenty of people saying "But imagine if it did work! We could get to other stars in a few years!" but you always get crazy optimists that ignore all the evidence with stuff like this (c.f. solar roadways).
The post shared by the above poster shows the upvoted crazy optimists,
https://news.ycombinator.com/item?id=12957537
https://news.ycombinator.com/item?id=12957537
Day made. Good chuckle that.
Sorry if this is a stupid question, but what is thermal drift in this context?
Not a stupid question -- sorry for the jargon.
It is what is mentioned in this fragment of the article:
"When power flows into the EmDrive, the engine warms up. This also causes the fastening elements on the scale to warp, causing the scale to move to a new zero point"
Basically, thermal expansion of the thruster and the measurement device causes the rest position of the thrust balance to drift with time, which is hard to differentiate from the actual thrust generated. This is most critical when the thrust-to-weight ratio is low, as is the case here.
It is what is mentioned in this fragment of the article:
"When power flows into the EmDrive, the engine warms up. This also causes the fastening elements on the scale to warp, causing the scale to move to a new zero point"
Basically, thermal expansion of the thruster and the measurement device causes the rest position of the thrust balance to drift with time, which is hard to differentiate from the actual thrust generated. This is most critical when the thrust-to-weight ratio is low, as is the case here.
For everyone that's disappointed, remember that thrust without reaction mass is still possible with enough electrical power and lasers, and doesn't appear to violate any known laws of physics.
https://en.wikipedia.org/wiki/Photon_rocket
https://en.wikipedia.org/wiki/Nuclear_photonic_rocket
https://en.wikipedia.org/wiki/Laser_propulsion
https://en.wikipedia.org/wiki/Photon_rocket
https://en.wikipedia.org/wiki/Nuclear_photonic_rocket
https://en.wikipedia.org/wiki/Laser_propulsion
It's also possible without any energy transmission using lasers etc. as long as you are in some non-flat spacetime (i.e. there is some mass in your vincinity). It's called "swimming in spacetime" [1]
[edit] You can find a less scientific / more illustrative introduction to the concept here [2].
[1] http://groups.csail.mit.edu/mac/users/wisdom/swimming.pdf
[2] http://www.brophy.net/Downloads/AIL%20Class%20on%20Reality%2...
[edit] You can find a less scientific / more illustrative introduction to the concept here [2].
[1] http://groups.csail.mit.edu/mac/users/wisdom/swimming.pdf
[2] http://www.brophy.net/Downloads/AIL%20Class%20on%20Reality%2...
> as long as you are in some non-flat spacetime (i.e. there is some mass in your vincinity)
I'm not an expert, but isn't that definitionally everywhere? Or is it that it works better when your vicinity is more curved? The paper is a bit beyond my ability to get anything from, and the summary on Wikipedia isn't much better, and also doesn't seem to match what you're implying it is.
> “Swimming in spacetime” is a geometrical motive principle that exploits the curved spacetime metric of the gravitational field to permit an extended body undergoing specific deformations in shape, to change position. In weak gravitational fields, like that of Earth, the change in position per deformation cycle would be far too small to detect, but the concept remains of interest as the only unambiguous example of reactionless motion in mainstream physics.
I'm not an expert, but isn't that definitionally everywhere? Or is it that it works better when your vicinity is more curved? The paper is a bit beyond my ability to get anything from, and the summary on Wikipedia isn't much better, and also doesn't seem to match what you're implying it is.
> “Swimming in spacetime” is a geometrical motive principle that exploits the curved spacetime metric of the gravitational field to permit an extended body undergoing specific deformations in shape, to change position. In weak gravitational fields, like that of Earth, the change in position per deformation cycle would be far too small to detect, but the concept remains of interest as the only unambiguous example of reactionless motion in mainstream physics.
I also found the paper hard to read, but check page 6 of the pdf at http://www.brophy.net/Downloads/AIL%20Class%20on%20Reality%2... (Adventures in Curved Spacetime, Eduardo Guéron, Scientific American Vol.301)
This is a perfectly realistic technique that has already been seen in use: https://www.youtube.com/watch?v=Lnvh08GBOII
Photon drive is not "thrust without reaction mass", because photons do have mass (they have zero rest mass, but are never at rest). Mass of a photon is, unsurprisingly, E/c^2, where
E=h\omega. If photons had zero mass, they would not have been influenced by gravity, and bending of light by the solar mass has been measured in the beginning of 20th century.
You're using outdated terminology. Modern physicists use "mass" to refer to what was called "rest mass" shortly after relativity was developed in order to distinguish it from the new concepts they at the time called "relativistic mass" and "inertial mass". The term "relativistic mass" was motivated in part by the desire to still think of all gravitation as being sourced by some sort of mass, but the modern terminology is to say that gravity is sourced by the stress-energy tensor, of which (rest) mass is just one component.
Modern physicists unequivocally say "a photon has zero mass, but has non-zero momentum and energy".
Modern physicists unequivocally say "a photon has zero mass, but has non-zero momentum and energy".
I have a physics degree and still say that photons have zero rest mass, and then parenthetically mention that they never rest, precisely because of the issues of communication that tend to arise when we talk about things like thrust.
I'm always tailoring it to the audience because sometimes physics metaphors need to be unpacked when communicating. I have run into people who think that the "hole" that can move around in a lattice is an actual particle, not a quasiparticle, like it was a swimmy little positron just sitting in there, simply because the metaphoric shorthand had overtaken reality.
If I were talking physics grad to physics grad, I wouldn't do that. Anyone else? Yeah, brushing the complexities under the rug with shorthand leads to, well ... the idea that you can get thrust without kicking something in the other direction.
I'm always tailoring it to the audience because sometimes physics metaphors need to be unpacked when communicating. I have run into people who think that the "hole" that can move around in a lattice is an actual particle, not a quasiparticle, like it was a swimmy little positron just sitting in there, simply because the metaphoric shorthand had overtaken reality.
If I were talking physics grad to physics grad, I wouldn't do that. Anyone else? Yeah, brushing the complexities under the rug with shorthand leads to, well ... the idea that you can get thrust without kicking something in the other direction.
I wasn't advising him to not explain things, I was pointing out that he's saying something that's false when interpreted with standard terminology.
It is not false, because I made clear what mass I am talking about. Dogmatic nit-picking may satisfy your wish to feel superior to the great unwashed masses, but it is not particularly helpful.
I am aware of Okun's campaign to eliminate the term "realtivistic mass". I am not sure I am 100% on board with this, because the concept of "relativistic mass" is intuitive and practically useful (used by engineers working on particle accelerators, for ex.).
For instance, if a quantity of photons is put into reflective mirror box, when you put it into the scale, the measured weight will increase by E/c^2 (both before and after the photons are absorbed).
For instance, if a quantity of photons is put into reflective mirror box, when you put it into the scale, the measured weight will increase by E/c^2 (both before and after the photons are absorbed).
That terminology is outdated. Today, mass generally means invariant mass, corresponding to rest mass in case of 'massive' particles. The invariant mass of photons is 0, hence it's 'massless'.
The gamma factors hidden by the relativistic mass definition of course still occur, but they get folded into the 4-vector quantities instead, which happens naturally if you use proper time for your derivatives.
This way, we avoid having to introduce things like transverse and longitudinal mass, which was the explanation within the variable-mass picture as to why the spatial part of 4-acceleration generally isn't parallel to 3-acceleration.
edit: s/velocity/acceleration/ where appropriate
The gamma factors hidden by the relativistic mass definition of course still occur, but they get folded into the 4-vector quantities instead, which happens naturally if you use proper time for your derivatives.
This way, we avoid having to introduce things like transverse and longitudinal mass, which was the explanation within the variable-mass picture as to why the spatial part of 4-acceleration generally isn't parallel to 3-acceleration.
edit: s/velocity/acceleration/ where appropriate
The photon paths bend due to the curvature of space-time caused by gravity. This does not mean that they have non-zero mass. iirc, it has been proved that photons have non-zero _momentum_ but I am not sure about mass.
As I understand it, the relevant thing for gravity is energy. Mass is a particular form of energy, which photons do not have. It's energy that causes space to bend, but in most cases energy-in-the-form-of-mass completely dominates.
Scott Manly did an overview of potential ways of propulsion in space including some very wacky setups. The most promising ones seem to be using nuclear or fusion reactions to accelerate tiny amounts of mass to very high speeds. The engineering issues are substantial of course. But definitely goes a bit beyond the limitations of chemical processes (i.e. burning fuels). https://www.youtube.com/watch?v=QEZv_OXA_NI
I'd say beamed energy propulsion is more promising for high speeds. That's because the main problem becomes keeping the vehicle from destroying itself with waste heat, and beamed propulsion keeps the waste heat back at the beam souce. You can even actively cool an object with laser light (via anti-Stokes scattering and the like.)
In the end it's all about a very simple equation: E(kin) = ½mv² so it's all about exhaust velocity. The closer you can get that to its theoretical maximum (e.g. c), the less reaction mass is required.
But the question still remains: is there a practical non-Newtonian way? We already know of rather impractical ones, such has deforming spacetime.
But the question still remains: is there a practical non-Newtonian way? We already know of rather impractical ones, such has deforming spacetime.
I've wondered if it would be possible to build an efficient rocket engine that accelerates its reaction mass so hard that it gains an appreciable amount of relativistic mass? The fundamental problem with interstellar travel is the amount of reaction mass you need to make the trip in a reasonable amount of time. The rocket equation is a harsh mistress. If you were accelerating each gram of propellant so hard that it gained a metric ton of relativistic mass you could bypass it, assuming you had some sort of lightweight yet near limitless power source.
You could use a synchrotron or linear accelerator to shoot charged particles out the back.
The LHC gets protons to 99.999999% of c.
The LHC gets protons to 99.999999% of c.
I mean, sure, ultimately mass==energy. It broadens your options but doesn't change the problem that you have to take it with you, it gets used up, and the more you take the more you have to use.
The difference is quantitative, but multiple magnitudes big: The ratio of impulse to mass is given by the exhaust velocity, and velocities for massive propellants barely reach 0.01% of the speed of light. Thus the thrust can be more than 10 000 times higher for the same propellant mass.
On the flip side, the exhaust velocity also determines the ratio of (kinetic) energy to impulse, so energy beam propulsion needs over 10 000 times more stored energy.
Energy beam propulsion is only viable if you have compact high-capacity energy storage available (antimatter?).
On the flip side, the exhaust velocity also determines the ratio of (kinetic) energy to impulse, so energy beam propulsion needs over 10 000 times more stored energy.
Energy beam propulsion is only viable if you have compact high-capacity energy storage available (antimatter?).
The thing is we know how to harvest solar energy while in space. Harvesting matter has been proposed with ram scoops but contrary to solar cells, these are just theoretical propositions.
Being able to use energy directly instead of propulsion mass would make a lot of travels more sustainable and with potentially lighter vehicles.
Being able to use energy directly instead of propulsion mass would make a lot of travels more sustainable and with potentially lighter vehicles.
I'm pretty sure the amount of energy you can harvest that way is a couple of orders of magnitude too small to be useful.
You can beam the energy to the spaceship from a planet or satellite for the first leg of the voyage in many physically plausible configurations.
Neat idea. How much energy do you lose (assuming a vacuum)?
You could imagine some kind of dish that catches the energy, but that's the extent of my knowledge -- I don't know how you'd convert it back to propulsion.
You could imagine some kind of dish that catches the energy, but that's the extent of my knowledge -- I don't know how you'd convert it back to propulsion.
>How much energy do you lose?
Not entirely the right question. Usually in spaceflight you are overwhelmingly concerned with efficiency, since you have to carry your fuel with you. But with laser-boosted light sails, you leave your engines at home. At reasonable distances, (100+ AU) most of the beam is wasted, but the spacecraft doesn't care about that.
https://en.wikipedia.org/wiki/Solar_sail#Interstellar_flight
Not entirely the right question. Usually in spaceflight you are overwhelmingly concerned with efficiency, since you have to carry your fuel with you. But with laser-boosted light sails, you leave your engines at home. At reasonable distances, (100+ AU) most of the beam is wasted, but the spacecraft doesn't care about that.
https://en.wikipedia.org/wiki/Solar_sail#Interstellar_flight
Your main losses will be just from inverse-square law. Even if your ship is reflecting a laser off its rear end, you can only focus the beam so much; at some point the spot size will be bigger than the ship, and you'll be in the inverse-square regime (same surface area, 1/r^2 energy within it).
That doesn't seem fundamental, though. You could have a series of relays that catch the beam, convert it to energy, and re-beam it out.
But I'm sure the efficiency would be awful, and if you have a chain of N of these things, now you're dropping off exponentially with N. And N is linear in distance. Hm... this isn't sounding like such a great workaround anymore.
Not to mention that the incoming beam would be shoving your relay forward. Does the outgoing beam push it backwards? I don't know how that works. (Even if it does, you'd be shoved forward proportionally to the energy loss.)
Bleagh. You'd be better off sending out a series of energy pellets well in advance that a traveling ship would scoop up along the way. That must be what Pac-Man was all about...!
But I'm sure the efficiency would be awful, and if you have a chain of N of these things, now you're dropping off exponentially with N. And N is linear in distance. Hm... this isn't sounding like such a great workaround anymore.
Not to mention that the incoming beam would be shoving your relay forward. Does the outgoing beam push it backwards? I don't know how that works. (Even if it does, you'd be shoved forward proportionally to the energy loss.)
Bleagh. You'd be better off sending out a series of energy pellets well in advance that a traveling ship would scoop up along the way. That must be what Pac-Man was all about...!
> That doesn't seem fundamental, though. You could have a series of relays that catch the beam, convert it to energy, and re-beam it out.
That's a lot of hardware to send out, though. With a dedicated relay you could afford very large collecting surfaces, to compensate a bit for the conversion/retransmission efficiency loss, but there's a bigger problem: you can't just put a chain of relays on a line inside a planetary system. You have to put them in orbit of the Sun (even if by proxy of an orbit around a planet/moon). This means your initial line of relays will quickly drift out of alignment, making the path through them much longer than beaming straight at a ship that's transferring between planets or out of the system. You'd have to put rings of relays at various heights above the sun to guarantee a reasonably short path, and that would take a lot of relays. And work only for a single plane - if you want relayed power at arbitrary plane, you'd have to build shells of relays - so the amount of satellites you need to deploy just squared.
That's a lot of hardware to send out, though. With a dedicated relay you could afford very large collecting surfaces, to compensate a bit for the conversion/retransmission efficiency loss, but there's a bigger problem: you can't just put a chain of relays on a line inside a planetary system. You have to put them in orbit of the Sun (even if by proxy of an orbit around a planet/moon). This means your initial line of relays will quickly drift out of alignment, making the path through them much longer than beaming straight at a ship that's transferring between planets or out of the system. You'd have to put rings of relays at various heights above the sun to guarantee a reasonably short path, and that would take a lot of relays. And work only for a single plane - if you want relayed power at arbitrary plane, you'd have to build shells of relays - so the amount of satellites you need to deploy just squared.
Hah! Very good points.
You don't even need a dish to catch the energy; just use a mirror that reflects the laser. You will lose energy to particles in the laser beam, and possibly also due to redshift.
There are different configurations to transfer energy to the space-craft that is converted to it's momentum https://en.wikipedia.org/wiki/Beam-powered_propulsion
You push the "ship" with a laser from a satellite.
Wouldn't you push your satellite in the opposite direction? Not saying that it isn't a good idea. The satellite might be in orbit, so it could use gravity to negate that.
Note that in contemporary usage, the term 'mass' without qualifier is normally understood as a reference to invariant mass (aka rest mass). Photons have energy, but no mass. They can be used for propulsion due to having nonzero momentum.
While the 'working mass' in this case is massless, nevertheless the spacecraft still loses its own actual mass as it accelerates, which is something you might not expect from something labeled as "thrust without reaction mass".
True. After sending out a photon of energy E, a spaceraft of mass m will have its (invariant!) mass reduced by a factor of sqrt(1 - 2E/mc²).
In terms of energies, this is all rather trivial conceptionally: Rest energy (aka 'mass') gets converted into the kinetic energies of the spacecraft and the photon.
In terms of energies, this is all rather trivial conceptionally: Rest energy (aka 'mass') gets converted into the kinetic energies of the spacecraft and the photon.
I mean I would just load couple of metric tons of antimatter in the ship and then just use up picked up interstellar space mass (1 atom per cubic meter is not much, but you will be moving trough shitload of them) along the way to annihilate. the faster you move the faster you will go up to a couple of limits. BUT deceleration may be a bit of a problem.
In 2003 a scientist published a paper about cyclic changes in the shape of a quasi-rigid body on a curved manifold. He shown that it can lead to net translation and/or rotation of the body in the manifold, so in simple words "swimming in space". I guess this is only possible on very large structures.
https://dspace.mit.edu/handle/1721.1/6706
https://dspace.mit.edu/handle/1721.1/6706
There is a nice experiment that shows light can move:
https://www.youtube.com/watch?v=Ng1X8mPJziA
Kudos for spending four hard years to publish a negative result! It will hardly make any of them famous, while it still is a very important result. Hopefully this means that we can leave the whole EmDrive debacle behind us once for all.
And to those that says that the outcome was given, and that they wasted their time, I'd say that we do have to sometimes try for the really long shots. In addition, it is important to show that we don't sweep any controversial results under the carpet just because they don't align with current "dogma".
And to those that says that the outcome was given, and that they wasted their time, I'd say that we do have to sometimes try for the really long shots. In addition, it is important to show that we don't sweep any controversial results under the carpet just because they don't align with current "dogma".
> Kudos for spending four hard years to publish a negative result!
All scientific results are positive, but I have the feeling people end up skewing their research just to show what they want to see. Yesterday I read a study [1] by the most renown Brazilian university claiming that the control of Covid on Brazilian football is bad because 11% of the players got it while in Germany only 0.5% were sick. Then I looked the data up and the Bundesliga has the exact same 11% [2], but the researchers chose a very specific time frame in which they didn't have many cases, just to "prove" their point.
This was easy to verify, but I wonder how many long term researches find gibberish results and no one will ever know.
[1] https://globoesporte.globo.com/sp/futebol/campeonato-paulist...
[2] https://www.sport1.de/fussball/bundesliga/2021/02/bundesliga...
All scientific results are positive, but I have the feeling people end up skewing their research just to show what they want to see. Yesterday I read a study [1] by the most renown Brazilian university claiming that the control of Covid on Brazilian football is bad because 11% of the players got it while in Germany only 0.5% were sick. Then I looked the data up and the Bundesliga has the exact same 11% [2], but the researchers chose a very specific time frame in which they didn't have many cases, just to "prove" their point.
This was easy to verify, but I wonder how many long term researches find gibberish results and no one will ever know.
[1] https://globoesporte.globo.com/sp/futebol/campeonato-paulist...
[2] https://www.sport1.de/fussball/bundesliga/2021/02/bundesliga...
Considering how much waste heat can be thrown off by high powered microwave stuff (as in the original resonating cavity waveguide horn setup of the emdrive, which people thought to be producing thrust), I am not surprised at all that the apparent thrust was thermal expansion and contractions.
Klystrons and TWTAs are not exactly known for being low wattage pieces of equipment, in terms of their TDP (thermal dissipated power). Ask anyone that's ever worked on a 1000W+ uplink power amplifier for two way geostationary satellite stuff... It's a lot of heat to get rid of.
So these guys are trying to duplicate results of like 1 millinewton per kilowatt, meaning you'll need a microwave source of at least 3-4kW, of course it's going to throw off a lot of heat.
I do wonder if any of the scientists trying to duplicate this effect have thought to bring in some commercial industry manufacturers of big C, X, Ku band TWTAs and get their advice on building a test rig.
Or to try modern small but high power GaaN SSPAa vs TWTAs...
https://www.cpii.com/docs/datasheets/17/t22ci_mkt326.pdf
https://www.cpii.com/products.cfm/153
Even very low powered terrestrial microwave radios are a lot of waste heat compared to what they output in rf. The radio head on a ptp microwave dish setup that is a 35W load on -48vdc might be outputting around +18 into the waveguide, equivalent to around 200 milliwatts. The rest is all radiated into the atmosphere and what it's mounted on. This why you'll see ridges of heatsink fins on the body of a full outdoor modern 18 or 23GHz radio. This is considered to be totally normal (a 35W 1024qam dual linear polarity radio with a capacity close to gigabit Ethernet line rate is sure a big improvement over a full 42RU rack size Harris Megastar 64QAM radio consuming 1800W from 25 years ago)
Klystrons and TWTAs are not exactly known for being low wattage pieces of equipment, in terms of their TDP (thermal dissipated power). Ask anyone that's ever worked on a 1000W+ uplink power amplifier for two way geostationary satellite stuff... It's a lot of heat to get rid of.
So these guys are trying to duplicate results of like 1 millinewton per kilowatt, meaning you'll need a microwave source of at least 3-4kW, of course it's going to throw off a lot of heat.
I do wonder if any of the scientists trying to duplicate this effect have thought to bring in some commercial industry manufacturers of big C, X, Ku band TWTAs and get their advice on building a test rig.
Or to try modern small but high power GaaN SSPAa vs TWTAs...
https://www.cpii.com/docs/datasheets/17/t22ci_mkt326.pdf
https://www.cpii.com/products.cfm/153
Even very low powered terrestrial microwave radios are a lot of waste heat compared to what they output in rf. The radio head on a ptp microwave dish setup that is a 35W load on -48vdc might be outputting around +18 into the waveguide, equivalent to around 200 milliwatts. The rest is all radiated into the atmosphere and what it's mounted on. This why you'll see ridges of heatsink fins on the body of a full outdoor modern 18 or 23GHz radio. This is considered to be totally normal (a 35W 1024qam dual linear polarity radio with a capacity close to gigabit Ethernet line rate is sure a big improvement over a full 42RU rack size Harris Megastar 64QAM radio consuming 1800W from 25 years ago)
Counterfactual: Assume it worked, let's say it's producing a millinewton per kilowatt.
That would mean one could put it on a spinning arm with a generator in the center and make overunity power.
If you ran it at 1 m/s, it would only produce 1 milliwatt (1 mN * 1 m/s). Underunity. If you ran it at a million metres per second, it would produce its own power, 1 kilowatt. And if you ran it at 2 million metres per second, it would produce twice the energy that it consumed.
2 million metres per second is 2000 km/s and less than 1% of light speed. Relativity can be ignored. Would it be possible to build such a system? In vacuum with UHMWPE wire, one could build a spinning system 2000 kilometers in diameter that would spin 3 times per second. The centripetal acceleration would be 200,000 gees. Wikipedia tells me this is in current ultracentrifuge acceleration range. https://en.wikipedia.org/wiki/Ultracentrifuge
That would mean one could put it on a spinning arm with a generator in the center and make overunity power.
If you ran it at 1 m/s, it would only produce 1 milliwatt (1 mN * 1 m/s). Underunity. If you ran it at a million metres per second, it would produce its own power, 1 kilowatt. And if you ran it at 2 million metres per second, it would produce twice the energy that it consumed.
2 million metres per second is 2000 km/s and less than 1% of light speed. Relativity can be ignored. Would it be possible to build such a system? In vacuum with UHMWPE wire, one could build a spinning system 2000 kilometers in diameter that would spin 3 times per second. The centripetal acceleration would be 200,000 gees. Wikipedia tells me this is in current ultracentrifuge acceleration range. https://en.wikipedia.org/wiki/Ultracentrifuge
If the investigating this drive did nothing else this is a good outcome.
"We were able to greatly improve our measurement technology as a result"
"We were able to greatly improve our measurement technology as a result"
Depending how far down the rabbit hole they go in weird microwave resonating cavities and power amplifiers, maybe something of practical use for radar systems or other uses of multi-kilowatt microwave band power amplifiers will come out of it.
Imagine making popcorn in 5 seconds.
Imagine giving half your building a migraine in 5.1 seconds because you didn't catch it in time and have now burnt the popcorn.
What's the burned popcorn->migraine connection?
Presumably, it triggers the fire alarm.
The smell of burnt popcorn can induce migraine in some people (such as myself).
I just had a look at Tajmar's other publications[0]. They read like science fiction (well, that's of course because in a way they are):
> Tajmar, M., and Assis, A.K.T., "Particles with Negative Mass: Production, Properties and Applications for Nuclear Fusion and Self-Acceleration", Journal of Advanced Physics 4, 77-82 (2015)
> Tajmar, M., and Bertolami, O., "Hypothetical Gravity Control and Possible Influence on Space Propulsion", Journal of Propulsion and Power 21(4), 692-696 (2005)
> Lörincz, I. and Tajmar, M., "Null-Results of a Superconducting Gravity-Impulse-Generator", 52nd AIAA Joint Propulsion Conference, AIAA-2016-4988, Salt Lake City, July 25-27 (2016)
I think his job ranks among the coolest positions in physics that I've come across: He does fundamental physics (something almost every physics undergrad dreams of doing), both theory and experiment and both quantum mechanics and General Relativity, and he literally does rocket science. Unreal. I didn't think such a position could exist.
[0]: https://tu-dresden.de/ing/maschinenwesen/ilr/rfs/forschung/f...
> Tajmar, M., and Assis, A.K.T., "Particles with Negative Mass: Production, Properties and Applications for Nuclear Fusion and Self-Acceleration", Journal of Advanced Physics 4, 77-82 (2015)
> Tajmar, M., and Bertolami, O., "Hypothetical Gravity Control and Possible Influence on Space Propulsion", Journal of Propulsion and Power 21(4), 692-696 (2005)
> Lörincz, I. and Tajmar, M., "Null-Results of a Superconducting Gravity-Impulse-Generator", 52nd AIAA Joint Propulsion Conference, AIAA-2016-4988, Salt Lake City, July 25-27 (2016)
I think his job ranks among the coolest positions in physics that I've come across: He does fundamental physics (something almost every physics undergrad dreams of doing), both theory and experiment and both quantum mechanics and General Relativity, and he literally does rocket science. Unreal. I didn't think such a position could exist.
[0]: https://tu-dresden.de/ing/maschinenwesen/ilr/rfs/forschung/f...
He's had some controversy in the past and had a bit of a quack reputation. It's nice to see this research done. When I saw the name associated with this I assumed the opposite result.
> He's had some controversy in the past and had a bit of a quack reputation.
Can you provide more details or, possibly, sources? Was it just because he dared considering (and testing) "crazy claims" like the EmDrive in the first place?
Can you provide more details or, possibly, sources? Was it just because he dared considering (and testing) "crazy claims" like the EmDrive in the first place?
My impression was that yes, the majority of controversy was around his areas of research. I first heard of Tajmar when researching Heim theory which was itself pretty controversial.
I am both unsurprised and disappointed. This is one of those things where it'd be _really cool_ if it worked, but also hugely unexpected.
I also might feel disappointment, but I think that the greater disappointment would come from learning that foundational principles in physics had been overturned, because what it would mean is that we've all done a really, unacceptably bad job of getting a true version of reality. The difference between Newtonian physics and Special Relativity is not so much as to shake basic scientific principles to their core. But overturning conservation of momentum is like saying that we're making up physical laws as we go along.
> but I think that the greater disappointment would come from learning that foundational principles in physics had been overturned, because what it would mean is that we've all done a really, unacceptably bad job of getting a true version of reality
Physicist here: that's not how physics works, at all. We don't even pretend to have a "true" (complete?) model of reality at all. There are many gaps in our knowledge. Unfortunately they are either so small, so large, or so high energy that we can't easily expand across those limits to our knowledge using data gathered from labs here on Earth. But every now and then you get a really simple test that demonstrates a gap in our knowledge that reveals new physics, and that's how we make advances.
If the Em drive were real, it would be just like the photoelectric effect or quantum-slit interference patterns: things which defy classical explanations but which are evidently quite real. And I assure you, those were NOT disappointments. Far from it--every physicist dreams of discovering such an experiment, and it would certainly win the Nobel prize.
Physicist here: that's not how physics works, at all. We don't even pretend to have a "true" (complete?) model of reality at all. There are many gaps in our knowledge. Unfortunately they are either so small, so large, or so high energy that we can't easily expand across those limits to our knowledge using data gathered from labs here on Earth. But every now and then you get a really simple test that demonstrates a gap in our knowledge that reveals new physics, and that's how we make advances.
If the Em drive were real, it would be just like the photoelectric effect or quantum-slit interference patterns: things which defy classical explanations but which are evidently quite real. And I assure you, those were NOT disappointments. Far from it--every physicist dreams of discovering such an experiment, and it would certainly win the Nobel prize.
"The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka' but 'That’s funny...'"
Isaac Asimov
Isaac Asimov
> but I think that the greater disappointment would come from learning that foundational principles in physics had been overturned,
That would have been exciting, actually. More stuff to learn, more natural laws to discover, more possibilities!
That would have been exciting, actually. More stuff to learn, more natural laws to discover, more possibilities!
I’m not a physicist, but it seemed unlikely that one can overturn a century of physics research by microwaving a bucket. Unlikely that something so obvious yet groundbreaking wasn’t encountered in any other experiment ever made, in one form or another.
> The difference between Newtonian physics and Special Relativity is not so much as to shake basic scientific principles to their core.
But it is! Before special relativity, conservation of mass was thought to be a law of physics; SR refined this law to conservation of mass-energy.
But it is! Before special relativity, conservation of mass was thought to be a law of physics; SR refined this law to conservation of mass-energy.
I think the difference here is that conservation of mass was an incomplete understanding of what was going on, and conservation of mass-energy was an evolution of the law.
If the EmDrive worked, it would mean that several foundational things are just wrong. Not incomplete, just completely wrong.
If the EmDrive worked, it would mean that several foundational things are just wrong. Not incomplete, just completely wrong.
But "refinement" is the correct word to use.
In the vast majority of scenarios, you can keep your conservation of mass separate from your conservation of energy. You only have to pay attention in very specific cases: fusion, fission, and relative velocities that are quite intense.
This refinement, which we see again and again in physics, is "oh, sure, if you do THIS, here's a correction you can apply ... should start showing up three or four sigfigs in."
In the vast majority of scenarios, you can keep your conservation of mass separate from your conservation of energy. You only have to pay attention in very specific cases: fusion, fission, and relative velocities that are quite intense.
This refinement, which we see again and again in physics, is "oh, sure, if you do THIS, here's a correction you can apply ... should start showing up three or four sigfigs in."
> But overturning conservation of momentum is like saying that we're making up physical laws as we go along.
We ARE making up physical laws as we go along. We see something unexpected, we try to find why it could be, we invent new possible laws of nature and we check if those laws are sticking to wall with experiments. What sticks to wall, is then called "law of nature", but it might nit be exact or true. We only know it fits what we've seen up to now.
We ARE making up physical laws as we go along. We see something unexpected, we try to find why it could be, we invent new possible laws of nature and we check if those laws are sticking to wall with experiments. What sticks to wall, is then called "law of nature", but it might nit be exact or true. We only know it fits what we've seen up to now.
> The difference between Newtonian physics and Special Relativity is not so much as to shake basic scientific principles to their core.
Special relativity says that the temporal order in which events happen can () depend on the frame of reference of the viewer, and thus, such events do not have any objective order in which they occur.
() that is, if their relative "time-position" is spacelike, or in other words, if light is "too slow" to travel from one event occurring to the other event occuring.
To add on top of this, it says that if faster-than-light particles exist, a chain of FoRs can be constructed such that an event happens before itself.
If that isn't shaking basic principles, I don't know what is.
Special relativity says that the temporal order in which events happen can () depend on the frame of reference of the viewer, and thus, such events do not have any objective order in which they occur.
() that is, if their relative "time-position" is spacelike, or in other words, if light is "too slow" to travel from one event occurring to the other event occuring.
To add on top of this, it says that if faster-than-light particles exist, a chain of FoRs can be constructed such that an event happens before itself.
If that isn't shaking basic principles, I don't know what is.
> [...] is like saying that we're making up physical laws as we go along.
Um .. what's your alternative description on how scientific knowledge comes about?
Um .. what's your alternative description on how scientific knowledge comes about?
[deleted]
Newtonian momentum is not conserved in Special Relativity. That is, momentum is conserved, but momentum is redefined - it's not just mass times velocity any longer. The new definition is more correct than the previous one.
Had this worked, it probably wouldn't have overturned conservation of momentum either. It might have redefined momentum again, though.
Had this worked, it probably wouldn't have overturned conservation of momentum either. It might have redefined momentum again, though.
This is unsurprising. I doubt there was anyone with a modicum of understanding of the physics (even the teams doing the testing) who expected it to work. That doesn't, however, mean that testing it was a waste of time. There was an anomalous result that has now been resolved. I think it's a vital scientific virtue to follow up anomalous results until they're satisfactorily resolved, no matter how ridiculous or physics-defying they seem.
The EmDrive was always a long shot, but it wasn't the only reactionless drive under investigation. Unlike the EmDrive, which never had a plausible physical mechanism for how it could work, the Woodward Effect [0] does have such a mechanism and has yet to be experimentally disproven. It exists in this weird place where it seems to be a straightforward theoretical prediction from general relativity; where, almost by exploiting a loophole in physics, the maths says you can get thrust without propellant, and much more of it than possible with a photon rocket for the same power. This, apparently, doesn't violate conservation of momentum, either, because the momentum would be carried by gravity waves, essentially "pushing" against distant masses throughout the universe. Whether this is actually predicted by general relativity or is a misapplication of the theory, is very subtle and not something I'm capable of evaluating.
This is being evaluated by NASA [1] -- not that that says very much, NASA will evaluate some pretty crazy things, see exhibit A: EmDrive -- but they've yet to achieve a negative result. Not that that says very much either -- EmDrive didn't have a negative result until it did. Still, while the chances of the Woodward effect working are small, I would still rate it as much, much higher than the EmDrive ever seemed to be. It's something to keep an eye on, anyway. There's also this interview with James Woodward [2] that might be of interest.
[0]: https://en.wikipedia.org/wiki/Woodward_effect
[1]: https://www.nasa.gov/directorates/spacetech/niac/2018_Phase_...
[2]: https://medium.com/predict/james-woodward-on-machs-principle...
The EmDrive was always a long shot, but it wasn't the only reactionless drive under investigation. Unlike the EmDrive, which never had a plausible physical mechanism for how it could work, the Woodward Effect [0] does have such a mechanism and has yet to be experimentally disproven. It exists in this weird place where it seems to be a straightforward theoretical prediction from general relativity; where, almost by exploiting a loophole in physics, the maths says you can get thrust without propellant, and much more of it than possible with a photon rocket for the same power. This, apparently, doesn't violate conservation of momentum, either, because the momentum would be carried by gravity waves, essentially "pushing" against distant masses throughout the universe. Whether this is actually predicted by general relativity or is a misapplication of the theory, is very subtle and not something I'm capable of evaluating.
This is being evaluated by NASA [1] -- not that that says very much, NASA will evaluate some pretty crazy things, see exhibit A: EmDrive -- but they've yet to achieve a negative result. Not that that says very much either -- EmDrive didn't have a negative result until it did. Still, while the chances of the Woodward effect working are small, I would still rate it as much, much higher than the EmDrive ever seemed to be. It's something to keep an eye on, anyway. There's also this interview with James Woodward [2] that might be of interest.
[0]: https://en.wikipedia.org/wiki/Woodward_effect
[1]: https://www.nasa.gov/directorates/spacetech/niac/2018_Phase_...
[2]: https://medium.com/predict/james-woodward-on-machs-principle...
I came here to mention the Woodward Effect. I had never heard of it until last week when someone here on HN mentioned the blog of Tom Mahood (a former master's student of Woodward) in an entirely different context (namely: UFOs). It ended up sending me on a deep dive into the subject and, ultimately, led me to an article by Mahood[0] about the Woodward effect. The upshot is:
> But Tom, is this stuff ……real?
> I….don’t…. know. And I say that after being involved in chasing it down for 10+ years. At this point, I see arguements on both sides.
> Fundamentally, the mathematics are extremely compelling. I have yet to come across anyone credible in General Relativity who can say why the derivation is incorrect. About as damning as I’ve heard is something along the lines of, “Wait,…This can’t be right….But I don’t know why it’s not right”. The math is straightforward.
> The effect (or something like it) has been demonstrated in a wide variety of different types of devices and experimental setups. Something has been observed if it’s merely capacitors being shuttled back and forth, but also with later generation devices composed of all PZT discs.
> […]
> As time progressed and the experimental apparatus more refined, the “effect” seemed to get smaller, and that’s a REAL bad sign. It was already well below what the theory predicted. That sets off alarm bells. After all this time, if something isn’t in hand to float around a table top, its should still at least be producing unequivocal results.
[0]: https://www.otherhand.org/home-page/physics/graduate-studies...
> But Tom, is this stuff ……real?
> I….don’t…. know. And I say that after being involved in chasing it down for 10+ years. At this point, I see arguements on both sides.
> Fundamentally, the mathematics are extremely compelling. I have yet to come across anyone credible in General Relativity who can say why the derivation is incorrect. About as damning as I’ve heard is something along the lines of, “Wait,…This can’t be right….But I don’t know why it’s not right”. The math is straightforward.
> The effect (or something like it) has been demonstrated in a wide variety of different types of devices and experimental setups. Something has been observed if it’s merely capacitors being shuttled back and forth, but also with later generation devices composed of all PZT discs.
> […]
> As time progressed and the experimental apparatus more refined, the “effect” seemed to get smaller, and that’s a REAL bad sign. It was already well below what the theory predicted. That sets off alarm bells. After all this time, if something isn’t in hand to float around a table top, its should still at least be producing unequivocal results.
[0]: https://www.otherhand.org/home-page/physics/graduate-studies...
Addendum: I just noticed that the EmDrive article has something to say about the Woodward effect:
> In a third paper, the Dresden physicists then describe their research on the “Mach-Effect Thruster”:
> “Here we have proven that the Mach-Effect-Thruster (an idea by J. Woodward) is unfortunately a vibration artifact and also not a real thrust.”
> In a third paper, the Dresden physicists then describe their research on the “Mach-Effect Thruster”:
> “Here we have proven that the Mach-Effect-Thruster (an idea by J. Woodward) is unfortunately a vibration artifact and also not a real thrust.”
I was looking at the image on the page and my brain was oscillating between "that looks like a science machine" and "that looks spot on like a quack perpetual motion machine."
I guess context really does drive perception.
I guess context really does drive perception.
Hmmm… those oscillations in your brain, did they feel perpetual? We need some more data to see if we can harvest their energy for motion.
There's a reason the US Patent Office requires a working model from inventors who would patent a perpetual motion machine. Every other kind of invention may be described on paper.
A TANSTAAFL-defying machine...
Ah, those April 1 jokes. Don't fall for them. Of course it did develop trust. It is the future of space propulsion.
Oh, bad timing. Tajmar worked 4 years to verify the results. But now quacks can blame April 1.
Look at the dates: the conference papers were published march 17-19. The interview was march 21.
Ion drives are the future, but hopefully gravitational drives. Otherwise we will not get far
Look at the dates: the conference papers were published march 17-19. The interview was march 21.
Ion drives are the future, but hopefully gravitational drives. Otherwise we will not get far
Shhh, stop ruining my joke!
Too bad the article dates two weeks back :D
Chris2048(2)
Kudos to the team working on this, it's not often we get definitive findings and an update about something that was "futurology hype" like this.
Not a failure. It's just science. Cool stuff either way.
Not a failure. It's just science. Cool stuff either way.
I’m disappointed to hear that, just because it’d be very useful for this to be a thing. But I love the science behind it, and this is the way it should be.
Yes the strange thing about this drive is it appeared to work with no solid theory behind it. Yes, there was some but my layman's understanding was that it was flawed.
It would have been so cool for something like that to have worked. We don't get many discoveries like that.
It would have been so cool for something like that to have worked. We don't get many discoveries like that.
> appeared to work with no solid theory behind it.
That, my friend is the very definition of Snake Oil.
> We don't get many discoveries like that
On the contrary, we get far more than our fair share of charlatans claiming physically impossible results. See also: Theranos, Energous, Fontus and a million other scam companies.
That, my friend is the very definition of Snake Oil.
> We don't get many discoveries like that
On the contrary, we get far more than our fair share of charlatans claiming physically impossible results. See also: Theranos, Energous, Fontus and a million other scam companies.
It's not snake oil if you have a weird unexplained effect, and:
A) you're not trying to sell anything to anyone
B) you fully open source the design, specifications, schematics and your notes, and invite any interested third party to try to duplicate or debunk the effect.
C) you intentionally refrain from making hyperbolic claims about how revolutionary your thing is, before it's been duplicated. Maybe some clueless third parties engaged in hyperbole but not the original creators of the concept.
Science is working as intended.
A) you're not trying to sell anything to anyone
B) you fully open source the design, specifications, schematics and your notes, and invite any interested third party to try to duplicate or debunk the effect.
C) you intentionally refrain from making hyperbolic claims about how revolutionary your thing is, before it's been duplicated. Maybe some clueless third parties engaged in hyperbole but not the original creators of the concept.
Science is working as intended.
It's snake oil if you, as an experimenter, has not absolutely ruled out what's the most likely (and mundane) explanation.
What's the saying? If a theoretician is right just once, he's a hero; if an experimentalist is wrong just once, he's a goat.
What's the saying? If a theoretician is right just once, he's a hero; if an experimentalist is wrong just once, he's a goat.
Nobody was selling emdrives (to my knowledge). It was more of a "Hey, this is a weird effect" and an effort to explain it. That's less snake oil and more science. Most of the time there is some explanation that doesn't break your framework. Sometimes there's a breakthrough as you figure out the new thing. Sometimes you can't figure it out.
Shawyer absolutely was soliciting investment. Anyone with a basic physics education could see his proposed mechanism was utter nonsense, so it's hard to be charitable towards his rather hyperbolic marketing.
I disagree. This is the definition of progress in fundamental science. The difference between science and snake oil is what you do after your first signal. Do you try to find every possible way why it could be wrong and most importantly do you let other people try, then it is science, like the faster than light neutrinos come in mind as another example. Or do you start selling and let other people not test it. Well then its snake oil
It's really unhealthy to call anything that doesn't fit into the known laws of physics or science "snake oil"
If the EmDrive team was trying to sell NFTs and sucker people into investing in their radical invention it would be snake oil. But instead they approached this very responsibly, saying "we don't understand why this works. help us figure it out."
That's science done right, and a lot of new science has moved forward by questioning and changing the known rules. Whether or not it happens here.
If the EmDrive team was trying to sell NFTs and sucker people into investing in their radical invention it would be snake oil. But instead they approached this very responsibly, saying "we don't understand why this works. help us figure it out."
That's science done right, and a lot of new science has moved forward by questioning and changing the known rules. Whether or not it happens here.
You're apparently missing the origins of this whole thing. Shawyer has been soliciting investment for it since 2001, making very hyperbolic claims.
This was indeed snake oil from very the start. A couple of people at NASA EagleWorks got permission to use some of their time and facilities to investigate it as a personal project. They did an extremely lazy attempt to control for errors, published their result without review, and the hype exploded.
The whole saga is rather frustrating tbh. We knew what the definitive result was going to be 4 years ago. Getting some improved measurement technology is cool and all, but I don't think we had to go about it this way.
This was indeed snake oil from very the start. A couple of people at NASA EagleWorks got permission to use some of their time and facilities to investigate it as a personal project. They did an extremely lazy attempt to control for errors, published their result without review, and the hype exploded.
The whole saga is rather frustrating tbh. We knew what the definitive result was going to be 4 years ago. Getting some improved measurement technology is cool and all, but I don't think we had to go about it this way.
I disagree. Something new that challenges areas of physics where our understanding is vague, like neutrino mass or dark matter - sure: feel free to explore new theories
Something that challenges something as solidly established as conservation of momentum: Snake oil.
Something that challenges something as solidly established as conservation of momentum: Snake oil.
Newtonian motion was pretty well established for hundreds of years until general relativity transformed our understanding of gravity.
Things seem "established" until evidence comes along indicating it may not be. It doesn't always result in a reevaluation, but there's times it does.
This feels like one of those times where there's those in the establishment are yelling at others that their studies are a waste of time and that they shouldn't bother....and if that advice was followed, we'd be missing many of the breakthroughs in knowledge we have today. Of course there will be many times they're unsuccessful. That's why accepting a negative result is a lauded part of the scientific process. Without the bravery required in challenging convention, we would never make progress.
Things seem "established" until evidence comes along indicating it may not be. It doesn't always result in a reevaluation, but there's times it does.
This feels like one of those times where there's those in the establishment are yelling at others that their studies are a waste of time and that they shouldn't bother....and if that advice was followed, we'd be missing many of the breakthroughs in knowledge we have today. Of course there will be many times they're unsuccessful. That's why accepting a negative result is a lauded part of the scientific process. Without the bravery required in challenging convention, we would never make progress.
I don't get why you are fixated on that term. They're literally not selling anything.
The whole point of the term "snake oil salesman" is that someone is getting defrauded, and a dishonest person is making a quick buck.
The whole point of the term "snake oil salesman" is that someone is getting defrauded, and a dishonest person is making a quick buck.
On Energeous, the science is sound in theory. In practice I don't believe the company will be able to execute; but transmitting power over RF is something we've understood for a long time (since Edison first demonstrated the technology).
I'm an investor in a competitor: Reach Labs which has systems in production powering swarms of low power devices wirelessly. I've seen the technology work in person.
I'm an investor in a competitor: Reach Labs which has systems in production powering swarms of low power devices wirelessly. I've seen the technology work in person.
What size and wattage load of devices?
> That, my friend is the very definition of Snake Oil.
Is it? How does a bicycle work?
https://www.nature.com/news/the-bicycle-problem-that-nearly-...
Is it? How does a bicycle work?
https://www.nature.com/news/the-bicycle-problem-that-nearly-...
According to science, a bumblebee shouldn't be able to fly. /s
A bicycle isn't some unknown mystery of the universe, the very article you linked lays it out pretty clearly. A bicycle's stability is a function of its mass distribution, geometry and the gyroscopic effect. Their exact relation depends on the bicycle and since there is no one standard SI unit of a bicycle in the Bureau international des poids et mesures, there is no apparent equation. The "nearly broke mathematics" in the title is just pure clickbait.
A bicycle isn't some unknown mystery of the universe, the very article you linked lays it out pretty clearly. A bicycle's stability is a function of its mass distribution, geometry and the gyroscopic effect. Their exact relation depends on the bicycle and since there is no one standard SI unit of a bicycle in the Bureau international des poids et mesures, there is no apparent equation. The "nearly broke mathematics" in the title is just pure clickbait.
I have found I can teach kids to ride a bike in (literally) seconds, just by not lying to them about how it works.
"Use the handlebars to stay up. Lean to turn." Just like that, and they're off. (I am absolutely not exaggerating.)
(And, no, gyroscope effect has nothing to do with it.)
They get the idea to twitch the handlebars the opposite way, to lean, all by themselves. Most never notice they are doing it.
"Use the handlebars to stay up. Lean to turn." Just like that, and they're off. (I am absolutely not exaggerating.)
(And, no, gyroscope effect has nothing to do with it.)
They get the idea to twitch the handlebars the opposite way, to lean, all by themselves. Most never notice they are doing it.
That’s because leaning is such a bad term to describe what happens! Even when I learned to ride bikes, it felt so strange that “you have to lean left/right”, cause I understood somehow that I’m a much more massive object and the center of masses is around my butt at best. So leaning doesn’t change much in mass/geometry/momentum configuration. You may shift a bike under you with your arms, but this is limited to their lengths.
What really happens is that you always fall either to the left or to the right. If you fall in a desired turn direction, you turn a little. If not, you turn even more than is required to support a normal turn, so that your bike moves below you to the point that now your mass part is to the other side of it, and now you fall in the other, initially desired direction. Then you quickly turn at where you need. With practice all this movement reduces to centimeters and very smooth curves at all joints.
You move and (importantly) rotate your bike under yourself. It has nothing to do with leaning, because it’s the road/front tire that make a difference in a balance, not your flanks. Leaning helps to not fall off the seat when you cycle, but not in turns.
It’s clearly a trainer’s delusion to me (that thing when your trainer explains things that do not actually work/exist but you translate or ignore these terms showing respect to a good man).
What really happens is that you always fall either to the left or to the right. If you fall in a desired turn direction, you turn a little. If not, you turn even more than is required to support a normal turn, so that your bike moves below you to the point that now your mass part is to the other side of it, and now you fall in the other, initially desired direction. Then you quickly turn at where you need. With practice all this movement reduces to centimeters and very smooth curves at all joints.
You move and (importantly) rotate your bike under yourself. It has nothing to do with leaning, because it’s the road/front tire that make a difference in a balance, not your flanks. Leaning helps to not fall off the seat when you cycle, but not in turns.
It’s clearly a trainer’s delusion to me (that thing when your trainer explains things that do not actually work/exist but you translate or ignore these terms showing respect to a good man).
Yet, in fact you and the bicycle are physically leaning throughout any turn. I.e., you are at an angle off vertical with your center of mass distinctly not directly above the line between the points where the tires contact the ground.
Normally the plane of the bike, normal to the axles, cuts right through your center of mass.
Starting a turn by leaning is not usual for experienced bikers, but certainly works. For a beginner, staying upright while going more or less straight is what they need to work out first, but that invariably involves some spontaneous turns, so both are practiced.
What a century of children have been told is to steer with the handlebars, which is a reliable recipe for spills.
Normally the plane of the bike, normal to the axles, cuts right through your center of mass.
Starting a turn by leaning is not usual for experienced bikers, but certainly works. For a beginner, staying upright while going more or less straight is what they need to work out first, but that invariably involves some spontaneous turns, so both are practiced.
What a century of children have been told is to steer with the handlebars, which is a reliable recipe for spills.
Given sufficient evidence, there's no need to have a solid theory of operation for a given claim. That said, if it contradicts known laws of physics that evidence had better be damn good.
and yet, SSRIs
you because there's no systemic understanding of SSRIs work? But you could say the same for most drugs. Most of the pharma industry is just targeting a specific protein without regard for how it fits into the system as a whole
If there is anything thoroughly Snake Oil in modern currency, it's Tokamak Fusion.
"Give us enough billions, we'll have one working in 2050. Or 2060, or someday. It won't produce any power, oh no, of course not. But give us ten times more money after 2050 (or 2060) and by 2100, or 2140, or anyway someday maybe, we will have a prototype power station for you.
"Sure, it will cost a hundred times as much for each kW-hr as whatever you will be using by then—and the plant will destroy itself after only two years—but it will be fusion power. And that will be so cool!"
Tokamak fusion is mainly a jobs program for hot-neutron physicists, to maintain a population ready to draw on for weapons work, but is also a massive boondoggle providing a steady flow of corruption money to well-connected pockets. (Hot-neutron physicists are not getting the $billions.) Every cent spent on Tokamak fusion is stolen from actually practical work.
So don't talk to me about snake-oil until after you kill Tokamak.
"Give us enough billions, we'll have one working in 2050. Or 2060, or someday. It won't produce any power, oh no, of course not. But give us ten times more money after 2050 (or 2060) and by 2100, or 2140, or anyway someday maybe, we will have a prototype power station for you.
"Sure, it will cost a hundred times as much for each kW-hr as whatever you will be using by then—and the plant will destroy itself after only two years—but it will be fusion power. And that will be so cool!"
Tokamak fusion is mainly a jobs program for hot-neutron physicists, to maintain a population ready to draw on for weapons work, but is also a massive boondoggle providing a steady flow of corruption money to well-connected pockets. (Hot-neutron physicists are not getting the $billions.) Every cent spent on Tokamak fusion is stolen from actually practical work.
So don't talk to me about snake-oil until after you kill Tokamak.
Out of interest is there another more promising controlled fusion option?
Not really. Fusion has inherent generic engineering problems, particularly DT fusion, that are independent of the details of plasma confinement.
I am interested in Field-Reversed Configuration, although it seems more practical for driving spacecraft.
Anything aneutronic that works will be infinitely better than Tokamak. If it doesn't have to work, you are back in Tokamak territory.
Anything aneutronic that works will be infinitely better than Tokamak. If it doesn't have to work, you are back in Tokamak territory.
This is like rationalism vs empiricism. It's nice when the empirical results align with the rational conclusion again.
These experiments were apparently well designed and thoroughly done - they just don't apply to actual EM-Drive but speculative [infrared laser version](https://www.reddit.com/r/Physics_AWT/comments/iz2d4x/darpa_l...) of it. There are [good theoretical reasons](https://aetherwavetheory.blogspot.com/2010/11/do-galaxies-sh...) for why EMDrive should work better with radiation longer than wavelenght of CMBR, i.e. vacuum fluctuations. Also the geometry of resonators tested is [very distant](https://i.imgur.com/zTrRFum.gif) from conical shape of EMDrive, mildly speaking - and actually nonsensical with respect to EMDrive theory, which is based on polarization during reflection under Brewster angle. I'd even suspect, that Tajmar published negative results for misleading designs intentionally for to slow-down Chinese competition in this research. Most probably they already tested conical resonators - because there is no good reason why not to simply do it - but they hide their data before public for to get more time for further research of it. The pathoskeptical Popular Mechanics journal repeatedly attempted to [dismiss if not discredit EMDrive technology](https://www.popularmechanics.com/science/a15323/temdrive-con...) and now it just jumped at new opportunity with all vehemence. The path to replication of original [R. Shawyer's EMDrive drive design](https://i.imgur.com/inLGS5G.jpg) is thus still fully opened.
If anyone's interested, Roger Shawyer (the inventor of the EMDrive) is speaking at the online APEC conference on April 3rd:
https://www.altpropulsion.com/events/apec-4-3-the-emdrive-qu...
https://www.altpropulsion.com/events/apec-4-3-the-emdrive-qu...
wasn't it already established that the force measured was related to current in the power cables or something?
Yea I definitely remember that being discussed previously. Basically the amount of current in the wires was large enough to cause deflections that that particular group did not have a good way to account for so my recollection was they mentioned it as a likely source of the displacement. I was sort of hoping somebody would hook this thing up on top of an air table and power it with a huge battery so it’s a fully closed / stand alone system and see if the setup starts drifting one direction when it turns on.
It's an important step to fix the observed flaw and then experimentally verify results are now as expected.
I am sad, but not surprised.
I really want something like this to work, and it may, one day.
Just not yet, I guess.
I really want something like this to work, and it may, one day.
Just not yet, I guess.
The knowledge that we have gained from this experiment is that the experimental data disagrees with the theoretical justificiation for the idea. That isn't the same as proving that the theory is wrong, even if that seems the more likely explanation. To be sure that the theory is wrong we would need an analysis of why that is the case and what were the false assumptions and faulty reasoning behind it. Any volounteers?
The original theoretical justification for why the EmDrive was supposed to work was also wrong. The idea was to use a cavity shaped like a truncated cone, such that the forces on the big end and the small end don't precisely cancel. But this neglects the force on the sloping sides, which (of course) balances everything out.
Here's a detailed analysis by Greg Egan showing why the EmDrive would not be theoretically expected to generate any thrust: https://www.gregegan.net/SCIENCE/Cavity/Cavity.html
Proponents tried to hand-wave these arguments away and claim that the EmDrive's empirical results were explained by new, unknown physics.
Here's a detailed analysis by Greg Egan showing why the EmDrive would not be theoretically expected to generate any thrust: https://www.gregegan.net/SCIENCE/Cavity/Cavity.html
Proponents tried to hand-wave these arguments away and claim that the EmDrive's empirical results were explained by new, unknown physics.
To the dustbin!
I had hope for the promise of the drive, but such as it is.science proceeded and now we know more.
I had hope for the promise of the drive, but such as it is.science proceeded and now we know more.
I'm sure this is no surprise to any professional physicists anywhere.
Why is this subject coming back?
A while ago they conducted this experiment in Earth's orbit and found that the drive basically pushes itself away from Earth's electromagnetic field. Sadly it's useless in deep space.
A while ago they conducted this experiment in Earth's orbit and found that the drive basically pushes itself away from Earth's electromagnetic field. Sadly it's useless in deep space.
I mean, that sounds like something that could be pretty handy for LEO satellites at least, though there are surely more effective and less convoluted ways of achieving that.
I wanted to believe
what are the inventor's credentials? I searched and searched and could only find vague descriptions like "scientist"
We're trapped like beavers
[deleted]
Relevant XKCD: https://xkcd.com/1404/
While I will accept these results if valid. I sincerely hope that other labs are able to reproduce these results and the concept isn't dismissed out of hand.
While it's good to have multiple labs trying to reproduce results, that needs to apply in both directions to ensure that no unintended bias caused issues.
While it's good to have multiple labs trying to reproduce results, that needs to apply in both directions to ensure that no unintended bias caused issues.
Feel free to cheer it on, but extraordinary claims require extraordinary evidence. All the evidence here has never been verifiable and comes across as experimental sleights of hand. Always reminded me of Eugene Podkletnov and his gravity shielding, an interesting research avenue with physical experiments sure, but no one can ever replicate what he has said is happening.
I sometimes enjoy to tin-foil that things like the emdrive and all those whacky navy patents are actually superpowers intentionally wasting the time of rivals. One space faring nation recently spent a lot research effort getting an emdrive into space to test it.
I sometimes enjoy to tin-foil that things like the emdrive and all those whacky navy patents are actually superpowers intentionally wasting the time of rivals. One space faring nation recently spent a lot research effort getting an emdrive into space to test it.
I'm not cheering anything on. I'm saying that there are many reputable groups that tried and got results. Including NASA themselves. It's important to disprove this solidly by having more than one group test and have a negative result.
I think it's total bs. That doesn't mean the proof it is bs doesn't deserve to be repeated.
I think it's total bs. That doesn't mean the proof it is bs doesn't deserve to be repeated.
Suppose there was a rally driver who would claim that rally cars could go much faster if they were always driven in reverse. He did some rudimentary experiments and might have found a significant improvement. The general public and other racing drivers, who in my analogy can all be wonderful people but happen to know little about the mechanics of cars, are naturally enthusiastic: a potential breakthrough in driving! But clearly we need more experiments. So other rally drivers get to work: they set up an elaborate system with ropes and pulleys so they can reverse the driver's position in the car and run a car as fast as they can, but in reverse, on a test track. What do they find? Sadly, their answer is somewhat inconclusive, probably negative, but perhaps the test track had many bends. So they would like to repeat the experiment on a track with a few more straight segments: they write grant proposals, build a track, and plan other test runs... and all the time their progress is eagerly followed by the general public.
Now suppose you are a car mechanic in all this. What are you to do? This cannot work! It flies completely in the face of the way cars are set up, not to speak of the disadvantages in air flow. So you can loudly dismiss the claim as preposterous early on, but then you will be called a pessimist and the public point out that at least the rally drivers are trying something new - what the bleep have you been doing all this time? So you just wait the whole thing out, see it come... and go.
I guess I should at least be happy that I did not buy any shares in EnDrive Inc?