Is Faster-Than-Light Travel or Communication Possible? (1997)(math.ucr.edu)
math.ucr.edu
Is Faster-Than-Light Travel or Communication Possible? (1997)
http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html
87 comments
The center of the galaxy is 32,000 light years away. 32,000 years will have passed at the center of the galaxy by the time you get there in your 3.2 second journey. If you then turn around and go back, another 32,000 years will have passed before you get home.
It might feel more like time travel than space travel.
It might feel more like time travel than space travel.
What I've always found interesting (not sure if there's a name for this) is kind of the idea that if you made such a trip, you might find by the time you arrive there in 3.2 seconds, the rest of humanity has figured out true FTL travel with the technology that was developed during those 32,000 years. As a result, you arrive in what might be the equivalent of a horse and buggy at the center of the galaxy versus what everyone else is riding around in.
There was an Episode in Andromeda that dealt with that same thing.
There was also an point in that episode since the FTL method they used was tethered to massive objects and hence only allowed for travel from on star system to another (or from one galaxy to another) the old fashioned non FTL method allowed them to explore many more things than with FTL travel the downside that 10,000's years would pass for everyone else every time they take a trip.
There was also an point in that episode since the FTL method they used was tethered to massive objects and hence only allowed for travel from on star system to another (or from one galaxy to another) the old fashioned non FTL method allowed them to explore many more things than with FTL travel the downside that 10,000's years would pass for everyone else every time they take a trip.
Lots of science fiction stories have this concept, but usually they talk about Slower-than-light, multi-generational space ships that takes centuries to reach the next star, only to find that during the last 100+ years, the destination planet has already been settled by humanity.
The wealthiest leave early thinking they might be getting the best and the first.
Poorer people leaving later get better and faster transit.
The only advantage of leaving early is the guarantee of getting a transit, instead of waiting for a better one to arrive later and find you got nothing at all.
Poorer people leaving later get better and faster transit.
The only advantage of leaving early is the guarantee of getting a transit, instead of waiting for a better one to arrive later and find you got nothing at all.
This is one of my theories about why there isn't any alien life around. There is some party far in the future with a beacon or message that shouts "JOIN US HERE IN THE MIDDLE OF GALAXY R345Q2 10 BILLION YEARS IN THE FUTURE!"
After about 10 thousand years of hearing the beacon and being alone we finally get restless and just build a couple thousand giant spaceships and join the rest of the universe in the most cosmopolitan place ever.
After about 10 thousand years of hearing the beacon and being alone we finally get restless and just build a couple thousand giant spaceships and join the rest of the universe in the most cosmopolitan place ever.
It's not a party, it's a restaurant :)
> This is one of my theories about why there isn't any alien life around.
Do we need a theory on this yet? I mean... out of all the planets we've explored reasonably thoroughly so far, 100% have had life at some point.
Do we need a theory on this yet? I mean... out of all the planets we've explored reasonably thoroughly so far, 100% have had life at some point.
I've not heard that Mars had life at some point in its history. In fact I've not heard mention of any planets hosting life in their past, do you have some sources that you can point me to?
It's about the definition of 'reasonably thoroughly'. We haven't explored much of Mars, having covered only single digit square kilometers up close (and most of that geologically).
Huh, this is a really fun thought experiment. Does anyone know any scifi books that explores this (or a similar) concept?
As vslira alluded: https://en.wikipedia.org/wiki/The_Restaurant_at_the_End_of_t...
Oh, I've read that five part 'trilogy' several times :) I guess I should have said...
Douglas Adams' books have been a major fixture of my life since I was 12. He really was ahead of his time. Actually I don't think said time he was metaphorically ahead of has come yet :)
Douglas Adams' books have been a major fixture of my life since I was 12. He really was ahead of his time. Actually I don't think said time he was metaphorically ahead of has come yet :)
"A Fire Upon the Deep" explores a related concept.
That's why it's called space-time right...
But length contraction means that, subjectively, you'll think you've only travelled a few hundred thousand kilometers.
This explains the famous line from Star Wars about the Millennium Falcon "making the Kessel run in less than 12 parsecs". George Lucas was obviously hip to the implications of special relativity.
I think the retconed explanation is that the kessel run involves going around a black hole. Bragging about parsecs is because the slower ships had to completely steer free of the blackhole, while faster ones could get closer and break free of it's gravity, thus shortening the overall distance traveled.
I prefer the explanation that Han Solo thought they were total rubes, and gave them some nonsense just to impress them.
Indeed, the fourth draft of the script has this comment after the "twelve parsecs" line: "Ben reacts to Solo's stupid attempt to impress them with obvious misinformation." The final draft says he's "obviously lying."
I feel like this ridiculous retcon involving black holes, rather than sticking to the simple human explanation of braggadocio, is a microcosm of everything that subsequently went wrong with the prequels.
Indeed, the fourth draft of the script has this comment after the "twelve parsecs" line: "Ben reacts to Solo's stupid attempt to impress them with obvious misinformation." The final draft says he's "obviously lying."
I feel like this ridiculous retcon involving black holes, rather than sticking to the simple human explanation of braggadocio, is a microcosm of everything that subsequently went wrong with the prequels.
After seeing Interstellar and some Black Science Man explanations this would also mean that the fastest ships would get to the finish decades after the slow ones due to gravity shenanigans.
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Still gonna need some inertial dampers though.
That bit about the particle is fascinating, but I am struggling to understand why a particle that travels at 0.99x of the speed of light is faster than a ship that travels at 1516x the speed of light. Is the Star Trek universe not subject to time dilation?
The star trek universe is not subject to physics in general. Sound traveling without air, time travel, FTL, Newton's Law being ignored, Creating/destroying matter, "beaming" people down to a planet, etc.
See also https://arxiv.org/pdf/1211.6468.pdf, which accompanies a theory recently published in the Archive of Formal Proofs: http://www.isa-afp.org/entries/No_FTL_observers.shtml
It states rigorously what it means to be an object ("observer"), and what it means to travel faster than light, and proves that observers cannot travel FTL. In special relativity, though, not GR yet.
It states rigorously what it means to be an object ("observer"), and what it means to travel faster than light, and proves that observers cannot travel FTL. In special relativity, though, not GR yet.
Thinking you can go faster than light for communication is the same as believing perpetual motion or even being a flat earther.
You can't do it, there are no hacks to do it. It's a law of the universe. No matter how many SciFi movies tell you other wise.
I just don't get the acceptance of this anti-scientific concept.
You can't do it, there are no hacks to do it. It's a law of the universe. No matter how many SciFi movies tell you other wise.
I just don't get the acceptance of this anti-scientific concept.
Flat earthers are a totally different thing. The shape of the Earth is a fairly simple physical fact about the universe. To deny it is to essentially deny even the most basic human ability to gather facts.
Perpetual motion and FTL travel are about physical laws, which are not known in full. We've got some really good theories with a lot of data to back them up, but the facts lie in the data, not the theories. The theories are subject to refinement and replacement as better data is obtained.
It is not known that perpetual motion or FTL are impossible. It is believed that they are impossible, because the best theories to explain current data say they are impossible. But there is room for new data and new theories.
It was not all that long ago that it was "scientific fact" that atoms were indivisible (that's what the word means, even), that velocities add linearly, that light propagates through a fixed medium, that matter is conserved, and that gravitational force is proportional to mass and inversely proportional to the square of distance.
I also don't see much "acceptance" of FTL as physical fact. I see it accepted a lot as a story device, but that's just because it's handy for making entertaining stories, not because there's any basis in physical fact. There's some "acceptance" of FTL as physical fact in that people don't completely rule it out, but that's entirely justified.
Perpetual motion and FTL travel are about physical laws, which are not known in full. We've got some really good theories with a lot of data to back them up, but the facts lie in the data, not the theories. The theories are subject to refinement and replacement as better data is obtained.
It is not known that perpetual motion or FTL are impossible. It is believed that they are impossible, because the best theories to explain current data say they are impossible. But there is room for new data and new theories.
It was not all that long ago that it was "scientific fact" that atoms were indivisible (that's what the word means, even), that velocities add linearly, that light propagates through a fixed medium, that matter is conserved, and that gravitational force is proportional to mass and inversely proportional to the square of distance.
I also don't see much "acceptance" of FTL as physical fact. I see it accepted a lot as a story device, but that's just because it's handy for making entertaining stories, not because there's any basis in physical fact. There's some "acceptance" of FTL as physical fact in that people don't completely rule it out, but that's entirely justified.
http://arxiv.org/abs/1005.4172
c is a bit more established than "scientific fact" like the behavior of atoms were once thought to be, it is very mathematical, as is the curvature of the earth being > 0. In principle new data could come in showing these things to be false, in the same sort of way twice 2 may not be 4.
Another similar fact almost beyond experimental disproval is https://en.m.wikipedia.org/wiki/Identical_particles
c is a bit more established than "scientific fact" like the behavior of atoms were once thought to be, it is very mathematical, as is the curvature of the earth being > 0. In principle new data could come in showing these things to be false, in the same sort of way twice 2 may not be 4.
Another similar fact almost beyond experimental disproval is https://en.m.wikipedia.org/wiki/Identical_particles
We've only been doing this science thing in a serious organized way for between 100 and 200 years depending on how you count it. It's only since WWII that we've done it in a really big heavily funded way (cold war and all that). You're probably right, but I can't bring myself to be quite as dogmatic about it.
I do very much doubt FTL, not only for the physics reasons but for other circumstantial ones. If FTL is possible then the Fermi paradox goes from being an intellectual curiosity to a near metaphysical emergency. If there is FTL then either we are absolutely alone or there are aliens everywhere and they are hiding from us or for some reason we can't see them. That's because the first expansionary intelligence to discover FTL will fill at least the galaxy if not the entire universe in a geological eye-blink. Since ubiquitous aliens hiding seems less likely, if a pathway to FTL were discovered I would immediately conclude that we are alone in the galaxy at least and possibly beyond.
I do very much doubt FTL, not only for the physics reasons but for other circumstantial ones. If FTL is possible then the Fermi paradox goes from being an intellectual curiosity to a near metaphysical emergency. If there is FTL then either we are absolutely alone or there are aliens everywhere and they are hiding from us or for some reason we can't see them. That's because the first expansionary intelligence to discover FTL will fill at least the galaxy if not the entire universe in a geological eye-blink. Since ubiquitous aliens hiding seems less likely, if a pathway to FTL were discovered I would immediately conclude that we are alone in the galaxy at least and possibly beyond.
Our galaxy is estimated to be at most around 180,000 light years in diameter.
Even at a fraction of the speed of light, the amount of time to expand and fill the galaxy is still an eye-blink in geologic time. Even in evolutionary timescales it's still an eye-blink -- the Cretaceous era ended about 66 million years ago.
I think the depressing truth is that we are alone in this galaxy. See [1] for Michael H. Hart's extremely compelling discussion of this idea.
[1] http://adsabs.harvard.edu/full/1975QJRAS..16..128H
Even at a fraction of the speed of light, the amount of time to expand and fill the galaxy is still an eye-blink in geologic time. Even in evolutionary timescales it's still an eye-blink -- the Cretaceous era ended about 66 million years ago.
I think the depressing truth is that we are alone in this galaxy. See [1] for Michael H. Hart's extremely compelling discussion of this idea.
[1] http://adsabs.harvard.edu/full/1975QJRAS..16..128H
>If FTL is possible then the Fermi paradox goes from being an intellectual curiosity to a near metaphysical emergency.
Maybe. Maybe not. This is how UFO conspiracy theorists reason - "Here are some phenomena I don't understand, I can't think of any plausible explanation for them, therefore, must be aliens".
There may be some hidden reasons why we can't detect FTL civilizations.
Maybe. Maybe not. This is how UFO conspiracy theorists reason - "Here are some phenomena I don't understand, I can't think of any plausible explanation for them, therefore, must be aliens".
There may be some hidden reasons why we can't detect FTL civilizations.
Way off in tangent land now but: while much of "ufology" is indeed silly, "the aliens are here but they are not communicating" is a valid hypothesis for the Fermi paradox (with or without FTL).
There are numerous rational reasons that an intelligence exploring the universe might choose to be very very careful about initiating communication to the point of taking steps to avoid even accidentally revealing itself. Some of these are altruistic (e.g. prime directive and contamination concerns) and some are self-interested (see game theory, and consider the apocalyptic destructiveness of conflict between really advanced intelligences).
There are numerous rational reasons that an intelligence exploring the universe might choose to be very very careful about initiating communication to the point of taking steps to avoid even accidentally revealing itself. Some of these are altruistic (e.g. prime directive and contamination concerns) and some are self-interested (see game theory, and consider the apocalyptic destructiveness of conflict between really advanced intelligences).
It seems implausible that all of the aliens would agree to ignore us, even less so for them to consistently arrive at that conclusion in an independent manner. Then again, Earth might be exceptionally boring and consistently uninteresting to spacefaring aliens. Who knows? Maybe life is really rare.
Possible doesn't necessarily mean easy.
This is exactly right given our current understanding of the universe. FTL travel violates causality, which is a fundamental principle of the universe.
I wouldn't go quite so far as to say it's totally impossible though. There is a whole lot about the universe we don't understand and I can't rule out the possibility that there are entire branches of mathematics and physics that we don't know about.
I wouldn't go quite so far as to say it's totally impossible though. There is a whole lot about the universe we don't understand and I can't rule out the possibility that there are entire branches of mathematics and physics that we don't know about.
Can you or someone else "explain to me like I'm five" why faster-than-light travel violates causality?
It's one of a bunch of mathematical conclusions of Special Relativity (the most famous one being that objects at rest have a "kinetic" energy of mc^2). I'll try to explain it simply, without the math:
Imagine a friend and you, moving very fast with respect to each other. You measure your friend's clock as advancing slowly (due to time dilation), on account of the fact that he's moving with respect to you. But your friend measures _your_ clock as advancing more slowly than _his_, because motion is relative.
The way to reconcile this mathematically is to give up on absolute simultaneity of distant events. In other words, when two things happen in different places, at the same time according to your clock, they happened at different times according to your friend's clock. This is analogous to how you measure your friend to be in different places in different times (because he's moving with respect to you), but he measures himself to be stationary, always in the same place. To recap: If comparing things at different moments, "being in the same position or not" is relative to the observer. If comparing things at different places, "happening at the same time or not" is relative to the observer.
That's how causality comes in. If your friend tosses a very fast ball at you, and the moment you receive the ball you start towards him faster-than-c, you'll arrive where he is before he tossed it (if you went fast enough). That's what the equations say. Now the breaking of absolute simultaneity allows naturally for disagreements on what of two things happened first, assuming they happened far enough from each other that light couldn't cover the distance in time. But by putting faster-than-c velocities in the equations, we have your friend and you disagreeing on what happened first (him tossing the ball, or you arriving where he is?) in what (to him) is the same place. And it's not just a confusion of the mind: all your measuring and recording artifacts will agree with you, and all of his will agree with him. The mathematical conclusion is that if you can send information faster-than-c, you can send it back in time and break causality.
Imagine a friend and you, moving very fast with respect to each other. You measure your friend's clock as advancing slowly (due to time dilation), on account of the fact that he's moving with respect to you. But your friend measures _your_ clock as advancing more slowly than _his_, because motion is relative.
The way to reconcile this mathematically is to give up on absolute simultaneity of distant events. In other words, when two things happen in different places, at the same time according to your clock, they happened at different times according to your friend's clock. This is analogous to how you measure your friend to be in different places in different times (because he's moving with respect to you), but he measures himself to be stationary, always in the same place. To recap: If comparing things at different moments, "being in the same position or not" is relative to the observer. If comparing things at different places, "happening at the same time or not" is relative to the observer.
That's how causality comes in. If your friend tosses a very fast ball at you, and the moment you receive the ball you start towards him faster-than-c, you'll arrive where he is before he tossed it (if you went fast enough). That's what the equations say. Now the breaking of absolute simultaneity allows naturally for disagreements on what of two things happened first, assuming they happened far enough from each other that light couldn't cover the distance in time. But by putting faster-than-c velocities in the equations, we have your friend and you disagreeing on what happened first (him tossing the ball, or you arriving where he is?) in what (to him) is the same place. And it's not just a confusion of the mind: all your measuring and recording artifacts will agree with you, and all of his will agree with him. The mathematical conclusion is that if you can send information faster-than-c, you can send it back in time and break causality.
I want to make sure I understand "time dilation," as you describe it. I have no formal background in science or math. So, please bear with me. For the sake of making the math easy, I'm going to talk about traveling faster than the speed of light, but only for the sake of argument. You'll see why.
I understand it this way. Assume I were traveling away from my friend at twice the speed of light. My time of departure is 12:00:00. After 1 second (my clock) I have traveled 2 light-seconds. Light reflected off the face of my clock now travels towards my friend, reading 12:00:01. We'll call this view of my clock a "snapshot."
From my friend's point of view, that snapshot reaches him at 12:00:03. Yes?
Now, we allow for 1 additional second, my time. I have traveled in total 4 light-seconds. My 12:00:02 snapshot now travels towards my friend. It reaches him at 12:00:06, his time. Yes?
So, from my friend's point of view, my time has seemed to slow down. Is that what you mean by time dilation?
I understand it this way. Assume I were traveling away from my friend at twice the speed of light. My time of departure is 12:00:00. After 1 second (my clock) I have traveled 2 light-seconds. Light reflected off the face of my clock now travels towards my friend, reading 12:00:01. We'll call this view of my clock a "snapshot."
From my friend's point of view, that snapshot reaches him at 12:00:03. Yes?
Now, we allow for 1 additional second, my time. I have traveled in total 4 light-seconds. My 12:00:02 snapshot now travels towards my friend. It reaches him at 12:00:06, his time. Yes?
So, from my friend's point of view, my time has seemed to slow down. Is that what you mean by time dilation?
Try not to think of time-dilation in relation to "light travelling". Time dilation just means that time passes more slowly for you due to your speed relative to an observer. So imagine you have an identical twin, and you leave on a Journey to a nearby solar system at say 0.9x the speed of light. Your twin stays on earth and for arguments sake you can say he is "stationary" in comparison to you.
When you come back, he'll be much more "aged" than you. You had a clock on-board your craft, and it measured your trip as say "2 years". Likewise, your twin also had a clock and it measured your trip as having lasted "20 years". The clocks are not wrong. And trust me, this isn't some science-fiction type thing we're discussing. GPS satellites orbiting the Earth carry very accurate atomic-clocks, and they need to take time-dilation into account in order to compensate for the drift in values, simply due to the accuracy necessary for GPS. Just had a look on the wiki page, and the drift is approximately 38 microseconds per day.
When I first encountered this concept in high-school randomly, I was quite shocked at how "non-complicated" the equation for it is.
https://en.wikipedia.org/wiki/Time_dilation#Simple_inference...
https://en.wikipedia.org/wiki/Global_Positioning_System
When you come back, he'll be much more "aged" than you. You had a clock on-board your craft, and it measured your trip as say "2 years". Likewise, your twin also had a clock and it measured your trip as having lasted "20 years". The clocks are not wrong. And trust me, this isn't some science-fiction type thing we're discussing. GPS satellites orbiting the Earth carry very accurate atomic-clocks, and they need to take time-dilation into account in order to compensate for the drift in values, simply due to the accuracy necessary for GPS. Just had a look on the wiki page, and the drift is approximately 38 microseconds per day.
When I first encountered this concept in high-school randomly, I was quite shocked at how "non-complicated" the equation for it is.
https://en.wikipedia.org/wiki/Time_dilation#Simple_inference...
https://en.wikipedia.org/wiki/Global_Positioning_System
In that first link, where it says (referring to the diagram at the bottom right), "Observer moving parallel relative to setup [...]," I don't understand. Parallel to what? Parallel to the mirrors? Parallel to the beam of light? I don't find it to be clear. Can you tell me which it is? Thanks.
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P.S. Never mind. I follow the diagram now. I'm trying to follow the rest of it.
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P.S. Never mind. I follow the diagram now. I'm trying to follow the rest of it.
Ah, good observation! But what you're describing isn't relativistic time dilation. It is called "the (non-Relativistic) Doppler effect", and can be commonly experienced when a race car, an ambulance, or a train passes you: When it's approaching, the noise will have a higher pitch than when it's passed. This is because the frequency of things that move towards us appear higher than they are, and that of things that move away from us appear lower. It's also why stars that move away from us appear more red than they are (they are said to be "red-shifted").
Imagine the same scenario you described (there's actually no need to use faster-than-c speeds for it), but your friend has planted clocks all along the path that you're traveling. Once he's back at his starting position, he synchronizes them all (there are techniques to achieve this - Einstein famously proposed one). Now when you pass him and keep moving away from him, every second you take a picture of your own clock next to the clock planted on the path. In a non-relativistic world, the pictures will show that your clock is always synchronized with all of your friend's clocks. Making the observation this way rids us of the Doppler effect.
But a non-relativistic world isn't the real world! In reality, if you go fast enough (close enough to c), the pictures will show e.g. your clock marking 12:00:01 when the clock in the path marks 12:00:02. And your clock marking 12:00:02 when you encountered the next clock in the path marking 12:00:04. In other words, your friend (and everything that's stationary with respect to him) will measure your time passing more slowly. Using these example numbers, in what for them is the pass of 2 seconds, you (and everything moving at your same speed - like your clock) have only aged 1 second. This is relativistic time dilation. It's shocking, but it's a fact that's been established for 110 years (and its mathematical consequences help explain even the microelectronics you and me are using). Now this happens no matter what speed you move with respect to your friend. But for everyday speeds it's so small as to be imperceptible - it only becomes noticeable at speeds like that of GPS satellites.
An immediate question is:
> Wait, if I move away from my friend, from my point of view my friend is moving away from me. So I should measure his clocks advancing more slowly than mine.
And that is correct, and is exactly what would happen!
> But the pictures I took show the opposite?
No! They show your clock compared to different clocks. And these clocks on the path, that your friend synchronized, by your measurements they all started at different times. I.e. for you, none of these clocks are synchronized. For your friend, they all marked 12:00:00 simultaneously. For you, they all marked 12:00:00 at different moments. In non-relativistic physics, simultaneity was an absolute concept: If two things happened at the same time, they happened at the same time for everybody. In reality, if I'm moving with respect to you, what happens at the same time in different locations for me, doesn't happen at the same time for you.
Imagine the same scenario you described (there's actually no need to use faster-than-c speeds for it), but your friend has planted clocks all along the path that you're traveling. Once he's back at his starting position, he synchronizes them all (there are techniques to achieve this - Einstein famously proposed one). Now when you pass him and keep moving away from him, every second you take a picture of your own clock next to the clock planted on the path. In a non-relativistic world, the pictures will show that your clock is always synchronized with all of your friend's clocks. Making the observation this way rids us of the Doppler effect.
But a non-relativistic world isn't the real world! In reality, if you go fast enough (close enough to c), the pictures will show e.g. your clock marking 12:00:01 when the clock in the path marks 12:00:02. And your clock marking 12:00:02 when you encountered the next clock in the path marking 12:00:04. In other words, your friend (and everything that's stationary with respect to him) will measure your time passing more slowly. Using these example numbers, in what for them is the pass of 2 seconds, you (and everything moving at your same speed - like your clock) have only aged 1 second. This is relativistic time dilation. It's shocking, but it's a fact that's been established for 110 years (and its mathematical consequences help explain even the microelectronics you and me are using). Now this happens no matter what speed you move with respect to your friend. But for everyday speeds it's so small as to be imperceptible - it only becomes noticeable at speeds like that of GPS satellites.
An immediate question is:
> Wait, if I move away from my friend, from my point of view my friend is moving away from me. So I should measure his clocks advancing more slowly than mine.
And that is correct, and is exactly what would happen!
> But the pictures I took show the opposite?
No! They show your clock compared to different clocks. And these clocks on the path, that your friend synchronized, by your measurements they all started at different times. I.e. for you, none of these clocks are synchronized. For your friend, they all marked 12:00:00 simultaneously. For you, they all marked 12:00:00 at different moments. In non-relativistic physics, simultaneity was an absolute concept: If two things happened at the same time, they happened at the same time for everybody. In reality, if I'm moving with respect to you, what happens at the same time in different locations for me, doesn't happen at the same time for you.
My understanding of it is that it all goes to crap when outside observers manage to see the outcome of your event before they see the event started. Therefore, to be safe, keep your faster-than-light travel a secret.
Effectively, the speed of light is the rate at which Cause and Effect propagate through the universe.
The speed of light isn't an intrinsic property of light, it just so happens that light travels that fast and it was the first thing we were able to measure that was traveling at the limit.
If you were traveling at FTL velocities, you would effectively get there before you left.
The speed of light isn't an intrinsic property of light, it just so happens that light travels that fast and it was the first thing we were able to measure that was traveling at the limit.
If you were traveling at FTL velocities, you would effectively get there before you left.
> If you were traveling at FTL velocities, you would effectively get there before you left.
To be more exact, aren't you saying that you would seem to get there before you left, from the point of view of someone not traveling with you who is observing you from some particular vantage point?
To be more exact, aren't you saying that you would seem to get there before you left, from the point of view of someone not traveling with you who is observing you from some particular vantage point?
would the observer's time slow down enough to run negative (backwards) from the POV of those traveling FTL ?
What if you arrived at some point after you actually left? (Not the other data of you leaving arriving at that point)
Granted I believe that doing so would probably involve bending space/time so that your actual position was in the new frame.
Granted I believe that doing so would probably involve bending space/time so that your actual position was in the new frame.
You're still getting there at a point in time earlier than the universe permits. This is essentially the same as traveling backwards in time, and violating causality by allowing effect to precede cause.
To travel faster than light, you'd have to skip places in space instead of moving through them continuously. So you'd be constantly appearing out of nowhere.
Other reasons.
Other reasons.
It would allow you to send information backwards in time.
>>fundamental principle of the universe.
Fundamental principles of the universe also say heavier than air machines should be impossible.
FTL issue is the same thing. Its possible, it just won't happen in the way we might expect.
Fundamental principles of the universe also say heavier than air machines should be impossible.
FTL issue is the same thing. Its possible, it just won't happen in the way we might expect.
You are way too sure about this. Everything we know tells us that this is a fundamental limit, but we don't know everything. For example, wormholes are still within theoretical possibility. Maybe there is some exotic aspect of reality that could imply FTL travel, causality be damned.
Everything we know tells us that energy being conserved is a fundamental limit, but we don't know everything. For example, exotic physics that allows us to pull energy from the cosmological constant itself is still a theoretical possibility. Maybe there is some exotic aspect of reality that could violate energy conservation.
My point being that, yes, these two are comparable, which is what the claim you are replying to said.
In fact, belief in FTL is sillier that violation of conservation of energy. We have no evidence for FTL of any kind. We do have some reason to believe that conservation of energy is in fact violated at cosmological scales by the increasing rate of expansion of the universe. (Perhaps future understandings will resolve this apparent violation with a more complete picture of "energy", but at the moment, what we know of as energy is not being conserved at that scale.)
My point being that, yes, these two are comparable, which is what the claim you are replying to said.
In fact, belief in FTL is sillier that violation of conservation of energy. We have no evidence for FTL of any kind. We do have some reason to believe that conservation of energy is in fact violated at cosmological scales by the increasing rate of expansion of the universe. (Perhaps future understandings will resolve this apparent violation with a more complete picture of "energy", but at the moment, what we know of as energy is not being conserved at that scale.)
I don't get the thought process that locks this possibility out. Imagine you are a simulated entity inside simulated universe - v100000 of Eve Online.
There are rules that you can see and access, and those you cannot. Both are in some sense irrelevant to your own perception of truth because they are determined outside the bounds of your empirical experience.
What good evidence do you have to refute such an explanation [surely its likelihood increases in line with our own ability to create the 'next turtle down'].
There are rules that you can see and access, and those you cannot. Both are in some sense irrelevant to your own perception of truth because they are determined outside the bounds of your empirical experience.
What good evidence do you have to refute such an explanation [surely its likelihood increases in line with our own ability to create the 'next turtle down'].
And in the early 1000s humans believed that we would never fly a few people strapped to a giant rocket to the moon. They believed that because the technology to do it hadn't been invented yet and we had no idea it was possible.
We have to learn how to do it and then we will do it.
We have to learn how to do it and then we will do it.
Flying didn't violate the basis premises of physics. Also it exacerbates the issue wherein space doesn't appear to be full of aliens. Even a few races in the galaxy expanding with slower than light travel could fill the galaxy in tens of thousands of years. Now imagine how fast the universe fills up with ftl travel
What if physics is like a computer?
You have atoms and quants and whatnot. Now you add one and one another. You keep adding and soon or matter there is a slip. Basically you get the universe to a buffer overflow. All still following the laws of physics. Like you get a cpu limited of his numbers you get the universe to a buffer overflow.
Now one could say, but the universe is endless. Which means you would need endless energy for that buffer overflow.
But who says you need to create that buffer overflow in the whole universe and not in a cube? And who says the universe is endless?
You have atoms and quants and whatnot. Now you add one and one another. You keep adding and soon or matter there is a slip. Basically you get the universe to a buffer overflow. All still following the laws of physics. Like you get a cpu limited of his numbers you get the universe to a buffer overflow.
Now one could say, but the universe is endless. Which means you would need endless energy for that buffer overflow.
But who says you need to create that buffer overflow in the whole universe and not in a cube? And who says the universe is endless?
But some objects in space are already moving faster than speed of light in vacuum. [1]
[1] https://www.youtube.com/watch?v=RaELad94KZs
[1] https://www.youtube.com/watch?v=RaELad94KZs
But you can still create the illusion of moving faster than light by freezing everybody for the duration of the experiment. That might be good enough.
You don't need that. Time dilation already does that for you. There is no apparent limit to subjective velocities.
I agree with the link that it really depends on what you mean by FTL. At first glance refrigerators seem impossible because they would reverse entropy. The key is that it does not practically matter if they do or not, they just need to achieve the desired result. I would personally consider FTL anything that would beat light traveling through unaltered space-time.
Two previous discussions: https://hn.algolia.com/?query=Is%20Faster-Than-Light%20Trave....
There should be (1998) in the title.
Not that it changes much...
Not that it changes much...
Nice list and currently no. But many theory's that say it is possible, no experiments shown it to happen and indeed faster than light gets for many down to causality. Not saying it is impossible, but in theory anything is possible until proven or disproven.
Another article that raises the same question is http://www.bbc.com/future/story/20150318-will-we-ever-speak-...
Now one aspect I'll add is that it may be possible but would the integrity of the information communicated be maintained and with that it would still be a case of no.
For me a related theory is that black holes convert mass into energy and that energy dissociates with current space and time and some of that ends up at physical location in space of 0,0,0 and time 0 as that is the earliest point in time and space. That and with all black holes over time venting so to speak to that point in space in time, was the reason for the big bang. Again a theory of mine. Now in that case something from now has gone back in time and yet has it gone faster than light? Or indeed is there anything sent that is recognisable from when it entered and in that case - no. So again whilst FTL communication may be possible, the whole aspect of integrity of that communication is a whole other aspect.
Equally the speed of light, there is another theory that the speed of light has varied over time (VLS Variable light speed) and whilst some observations lend themselves to this, it is still a theory. So that is another aspect in this that needs to be factored in. In short light may of been faster in the past, or it may of been slower and that add's a whole new layer of complexity upon this issue.
Science is fun isn't it, be darn boring when we as a species learn it all, but not in any of our lifetimes and that for me is a good thing. Though like many theories and great scientists there are and still are people who just dismiss without debate and with that how many people in the past burned or killed for saying the earth is not flat. Still be interesting for constructive perspectives and debate upon this, but alas as a subject many just dismiss and blindly label. Which is sad, in any time, even today :(.
Another article that raises the same question is http://www.bbc.com/future/story/20150318-will-we-ever-speak-...
Now one aspect I'll add is that it may be possible but would the integrity of the information communicated be maintained and with that it would still be a case of no.
For me a related theory is that black holes convert mass into energy and that energy dissociates with current space and time and some of that ends up at physical location in space of 0,0,0 and time 0 as that is the earliest point in time and space. That and with all black holes over time venting so to speak to that point in space in time, was the reason for the big bang. Again a theory of mine. Now in that case something from now has gone back in time and yet has it gone faster than light? Or indeed is there anything sent that is recognisable from when it entered and in that case - no. So again whilst FTL communication may be possible, the whole aspect of integrity of that communication is a whole other aspect.
Equally the speed of light, there is another theory that the speed of light has varied over time (VLS Variable light speed) and whilst some observations lend themselves to this, it is still a theory. So that is another aspect in this that needs to be factored in. In short light may of been faster in the past, or it may of been slower and that add's a whole new layer of complexity upon this issue.
Science is fun isn't it, be darn boring when we as a species learn it all, but not in any of our lifetimes and that for me is a good thing. Though like many theories and great scientists there are and still are people who just dismiss without debate and with that how many people in the past burned or killed for saying the earth is not flat. Still be interesting for constructive perspectives and debate upon this, but alas as a subject many just dismiss and blindly label. Which is sad, in any time, even today :(.
When exactly were people burned alive, or killed in general, for saying the earth isn't flat? The first article of the _Summa Theologica_ discusses how to prove that the world is round; no Christian took Genesis' cosmography particularly seriously until biblical literalism and the Reformation.
You might be thinking of the heliocentricism mess; but Bruno was burned for beliefs that had nothing to do with heliocentricism, and Galileo was only confined to house arrest -- and that after the Pope had tried to compromise with him, and Galileo responded by putting the Pope's arguments into the mouth of a simpleton in a revised version of the _Dialogue Concerning Two World-Systems_.
This is a tangent to your main argument, but it's an important thing to get right; you can't reach truth if you start from misconceptions...
You might be thinking of the heliocentricism mess; but Bruno was burned for beliefs that had nothing to do with heliocentricism, and Galileo was only confined to house arrest -- and that after the Pope had tried to compromise with him, and Galileo responded by putting the Pope's arguments into the mouth of a simpleton in a revised version of the _Dialogue Concerning Two World-Systems_.
This is a tangent to your main argument, but it's an important thing to get right; you can't reach truth if you start from misconceptions...
http://www.biographybase.com/biography/Bruno_Giordano.html
Yip your right, my mistake, good to learn. Least none can name and was indeed thinking of Bruno at the time, my bad.
Thank you for the correction and sorry for the misconception correction by me.
Yip your right, my mistake, good to learn. Least none can name and was indeed thinking of Bruno at the time, my bad.
Thank you for the correction and sorry for the misconception correction by me.
Thanks for not turning it into a fight! (And I apologize for my contentious tone; I was inappropriately gearing up for battle there.)
I thought you might be thinking of Bruno, the scientist who really was burned at the stake; it's a good thing for everyone that this wasn't for his science. (Of course, it would've been better if people weren't burned at the stake in general. Certain modern elements have reminded us of how painful a death that was...)
I also learned a few things about Galileo from Biography Base's article on him; thanks for that link!
The more I learn about that case, the less it sounds like Religion versus Science and the more it sounds like a conventional miscarriage of justice. A frail, sick, stubborn old man should never have been treated like that, even though he did call the Pope a simpleton. The Pope is the Pope, and has certain standards to maintain; it doesn't reflect well on Christ when His Vicar abuses the courts to make trouble for people who insult him.
I thought you might be thinking of Bruno, the scientist who really was burned at the stake; it's a good thing for everyone that this wasn't for his science. (Of course, it would've been better if people weren't burned at the stake in general. Certain modern elements have reminded us of how painful a death that was...)
I also learned a few things about Galileo from Biography Base's article on him; thanks for that link!
The more I learn about that case, the less it sounds like Religion versus Science and the more it sounds like a conventional miscarriage of justice. A frail, sick, stubborn old man should never have been treated like that, even though he did call the Pope a simpleton. The Pope is the Pope, and has certain standards to maintain; it doesn't reflect well on Christ when His Vicar abuses the courts to make trouble for people who insult him.
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If it is imaginable I believe it is possible. Within our current understanding of physics not doable, but that's just theory.
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He forgot the permutation operator in quantum mechanic... Where causality is put at the intrication level, and measurement of two intricated quantic system are coupled by one another if and only if you can make in the same hesienberg window of dE.dt ~ hbar/2. Hence potentially being an ansible (like in orson scott gard books. (quantum teleportation, alain aspect 1997)
The only problem is having synchronization of time over distance and hoping the dE.dt does not require exponential energy growth over intended distance of communication and that the energy per bit is not too expensive.
But yes this article was indeed done in 1998 where USA university may have discarded science from under developed countries such as France.
The only problem is having synchronization of time over distance and hoping the dE.dt does not require exponential energy growth over intended distance of communication and that the energy per bit is not too expensive.
But yes this article was indeed done in 1998 where USA university may have discarded science from under developed countries such as France.
A little math shows the relative velocity in which you travel one light year measured in a rest frame, in one year in your spaceship's frame, is 70.7% of the speed of light.
If you happened to be moving at the ludicrous speed of the "Oh-My-God" cosmic ray recorded in 1991, it would take you three seconds of your time to travel to the center of the galaxy.
That should be good enough for anyone!
https://www.fourmilab.ch/documents/OhMyGodParticle/