Physicists detect signs of neutrinos at Large Hadron Collider(phys.org)
phys.org
Physicists detect signs of neutrinos at Large Hadron Collider
https://phys.org/news/2021-11-physicists-neutrinos-large-hadron-collider.html
116 comments
Would there be any good reason or theoretically practical way to use neutrinos for communication?
Asking because in 3 Body Problem it’s seen as a “civilized” way to communicate compared to radio waves.
Asking because in 3 Body Problem it’s seen as a “civilized” way to communicate compared to radio waves.
While neutrinos are not very difficult to generate, they are extremely, astoundingly difficult to detect. Unless we discover a new type of matter that interacts more strongly with neutrinos, we're stuck with cavern-sized detectors that can detect single-digit numbers of neutrinos (out of many trillions), unreliably.
From the article:
"Casper said that there have only been about 10 observations of tau neutrinos in all of human history but that he expects his team will be able to double or triple that number over the next three years."
"Casper said that there have only been about 10 observations of tau neutrinos in all of human history but that he expects his team will be able to double or triple that number over the next three years."
Tau neutrinos, yes, but electron and muon neutrinos are significantly easier to identify - the problem with tau neutrinos is that when they interact, they produce a tauon, which very, very quickly decays so it's hard to know if it was a tauon decaying to, say, a muon or electron - which look identical to their respective neutrino flavours, or one of those neutrinos to begin with.
This is not to say that it's _easy_ to detect the other kinds, you still need a large number of neutrinos and a large volume for detection. The example that always comes up is submarine communication - which has two problems - detecting a sparse and intermittent signal to get a useful bitrate out, and generating a beam of sufficient intensity to begin with, let alone a beam that is steerable!
This is not to say that it's _easy_ to detect the other kinds, you still need a large number of neutrinos and a large volume for detection. The example that always comes up is submarine communication - which has two problems - detecting a sparse and intermittent signal to get a useful bitrate out, and generating a beam of sufficient intensity to begin with, let alone a beam that is steerable!
> Unless we discover a new type of matter that interacts more strongly with neutrinos
How about astrophage? :)
How about astrophage? :)
Fore those that haven't read it, "Hail Mary" from Andy Weir is a quite good book IMHO. It reads quite rapidly and it's very enjoying
[deleted]
I guess if we found a way to provide say a trillion times more neutrinos than normal we could detect that more easily.
your "opponent" is the sun that is bombarding us with tons of neutrinos. your SNR would be probably bad
Yea, this. 100,000,000,000 solar neutrinos pass through your thumbnail every second. This number is not substantially different at night, either.
What would be the number of photons falling per second on the same? :-)
Good question! I can't find a truly authoritative source, but a few calculations on the web put photon flux at the earth's surface at 10^21/m^2/s, give or take. Assuming your thumbnail is one square centimeter, that would be 10^17 photons per second, or 100,000,000,000,000,000, but only during the day :)
Interesting! So much higher than for neutrinos.
One follow up question. When reading about low-light cameras, the number of photons per pixel seem much smaller. I guess the following factors are involved:
Several orders of magnitude reduction under low light.
Pixel area likewise much smaller than thumb.
Exposure time less than a second.
Visible light vs. all spectrum.
Well, the question: Do the numbers fit? :-)
One follow up question. When reading about low-light cameras, the number of photons per pixel seem much smaller. I guess the following factors are involved:
Several orders of magnitude reduction under low light.
Pixel area likewise much smaller than thumb.
Exposure time less than a second.
Visible light vs. all spectrum.
Well, the question: Do the numbers fit? :-)
Unless I orient the thin edge of my thumbnail so I’m presenting the smallest possible cross section towards the sun!
I'm not embarrassed to admit I just tried this. I will walk around with thumbnail oriented thusly and make my observations. Perhaps the origin of the thumbs up? If anyone asks I will casually explain that I'm reducing my thumbail cross section to minimise the unknown effects of solar neutrinos.
If you can detect neutrinos below your thumb, I’m officially impressed!
The same problem is faced by optical communication during the day with the sensors exposed to sunlight. SNR can be increased a fair bit with even slight directionality. If sensitivity of detection is one day high enough, I think it would be theoretically possible to obtain directional information about neutrinos, by building a whole network of sensors and synthesizing an aperture.
For conventional electronic and optical purposes this isn't a huge deal. You "just" modulate the signal to be transmitted onto a fixed-frequency carrier, and have the receiver ignore everything that's not a sideband of that particular carrier frequency.
It's one of those cases where "just" really does apply. IR remote controls work this way, using a slow bitstream to key a 40 kHz carrier that drives the IR LED. Scientific applications that need even greater sensitivity can take advantage of the fact that the expected phase of the carrier is known as well as its frequency. Devices called lock-in amplifiers are used to run a wide variety of experiments and processes using that principle.
Doing this stuff with neutrinos rather than photons, however, is one of those * * * * * exercises that the textbook authors put in as a joke.
It's one of those cases where "just" really does apply. IR remote controls work this way, using a slow bitstream to key a 40 kHz carrier that drives the IR LED. Scientific applications that need even greater sensitivity can take advantage of the fact that the expected phase of the carrier is known as well as its frequency. Devices called lock-in amplifiers are used to run a wide variety of experiments and processes using that principle.
Doing this stuff with neutrinos rather than photons, however, is one of those * * * * * exercises that the textbook authors put in as a joke.
I think this would be impossible without truly alien materials.
Really? Seems like if we were motivated to do it, we could have a network of Earth satellite detectors in ~a century or so.
We need to put a few kilotons of extremely pure water (or maybe other transparent substance) into each satellite.
Not impossible, but likely this amount of orbital lift capacity is better used for other projects.
Not impossible, but likely this amount of orbital lift capacity is better used for other projects.
"If the sensitivity gets high enough" is the big if to my conjecture. We may never be able to detect enough neutrinos to be reliably detect multiple coming from the same source passing through multiple detectors.
[deleted]
Neutrinos are produced by radioactive decay, and they interact very weakly with ordinary matter, making them extremely difficult to detect.
Seems like the exact opposite qualities of something you'd want to use for communication.
Seems like the exact opposite qualities of something you'd want to use for communication.
If there were a way to reliably detect neutrinos in sufficient quantities they'd be ideal since you could send messages through the earth and at near light speed, I suppose.
This is important because… line of sight has somehow stymied us?
I feel like quantum entangled communication would be a better direction to head. Not that they’re mutually exclusive development paths.
I feel like quantum entangled communication would be a better direction to head. Not that they’re mutually exclusive development paths.
(un?)fortunately quantum entanglement cannot be used to send information any faster than classical communications. Entanglement is a good way to share bits for encrypting secrets, but you still need to be send entangled photons over a <c channel like a fiber optic or microwave cable.
Do neutrino's have a wavelength? If not then there'd be one channel and almost no way to prevent crosstalk.
As opposed to how we communicate now globally?
Communication via EM waves travel around the earth, not through it. (eg radio waves, fibre optic cables, satellite...)
But it's at pretty near the speed of light and how would there be an advantage to doing it the way the GP says?
Let the radius of the earth be R. Say you want to send a message from the north pole to the south pole.
If you use radio waves that travel around the earth, the shortest distance they can travel is πR ≈ 20,000km.
If you use neutrinos that travel through the earth, the shortest distance is 2R ≈ 12,700km.
So the advantage is about 7,300km (or in time units, 25ms ≈ 7,300km / (the speed of light))
If you use radio waves that travel around the earth, the shortest distance they can travel is πR ≈ 20,000km.
If you use neutrinos that travel through the earth, the shortest distance is 2R ≈ 12,700km.
So the advantage is about 7,300km (or in time units, 25ms ≈ 7,300km / (the speed of light))
You’re talking about using gigawatts of power, and detectors that weigh in at thousands of tons, in order to send a signal best measured in bits per decade. It’s an idiotic suggestion; fiber optics beat anything based on neutrinos hands–down. Authors who make their aliens use neutrino communications are idiots. But that’s ok, most authors are idiots, and most of them stopped taking physics in high school. Authors who take physics seriously are quite rare, even in the science fiction genre.
If you want a book written by someone who knows some real physics, read The Clockwork Rocket by Greg Egan. He changed one simple law of physics, worked out the consequences for quantum mechanics and relativity, made up some plausible–enough biology, and wrote a series of books in the resulting universe. The characters in the book have to discover or teach each other those laws, so the book is actually a pretty decent way to learn something of the laws of our own universe too. He wrote a huge amount of supplementary material as well, going into all the details. Truly an astounding accomplishment.
If you want a book written by someone who knows some real physics, read The Clockwork Rocket by Greg Egan. He changed one simple law of physics, worked out the consequences for quantum mechanics and relativity, made up some plausible–enough biology, and wrote a series of books in the resulting universe. The characters in the book have to discover or teach each other those laws, so the book is actually a pretty decent way to learn something of the laws of our own universe too. He wrote a huge amount of supplementary material as well, going into all the details. Truly an astounding accomplishment.
Awesome-- I've heard of him, but didn't know he had done so much detailed work on his stories. I'll check him out.
I am well aware of the "disadvantages" (to put it mildly) of hypothetical neutrino-based communications and I never suggested that they could viably replace EM-based communication
Fair enough, your calculation seems valid. But my point still stands -- are we going to build enormous LHCs all over the world to get a (maximum) 24 millisecond advantage in global communications via neutrinos?!
I assume the story is "if we find a magic new tech that is otherwise similar to our existing tech in terms of cost effectiveness, size, bandwidth, reliability, etc, and it also could pass straight through earth, then we could shave off 25ms and that would be useful"
> If there were a way to reliably detect neutrinos in sufficient quantities they'd be ideal since you could send messages through the earth and at near light speed, I suppose.
> As opposed to how we communicate now globally?
From this interaction I thought you'd missed the point that "send messages through the earth" is something we're currently not doing. Of course you're right that the "if there were a way to reliably detect neutrinos" is doing a lot of work.
> As opposed to how we communicate now globally?
From this interaction I thought you'd missed the point that "send messages through the earth" is something we're currently not doing. Of course you're right that the "if there were a way to reliably detect neutrinos" is doing a lot of work.
Just generate inordinate amounts of neutrinos. Doable for something akin to a undersea cable. If we could focus the output of the reaction then I see this being feasible, otherwise maybe not.
We can collect enough over hundred of days to make a picture of the sun*. Bear in mind the absolutely unimaginable quantities of neutrinos the sun is producing every femtosecond just in our direction and we can barely detect them with a giant apparatus.
https://apod.nasa.gov/apod/ap980605.html
https://apod.nasa.gov/apod/ap980605.html
The 'good reason' to use them for communication, if it were practical, is that they interact so weakly, you don't have to worry about pesky things like planets or stars getting in the way of your signal (though gravity is still a thing).
There have been (theoretical) proposals to use them to communicate with submarines: http://www.physics.ucla.edu/~hauser/neutrino_communication_p...
> Neutrinos have many properties that would make them superior even to the extremely low radio frequencies. Because neutrinos are nearly unaffected by matter, a neutrino beam could traverse directly through the earth from the transmission site to the submarine. A directional beam would allow confidential information to be passed only to the intended recipient. Neutrino communications would also be totally jam-proof. As an additional benefit, a neutrino message could be received in the deepest of waters, leaving a submarine less vulnerable to enemy attacks.
> Neutrinos have many properties that would make them superior even to the extremely low radio frequencies. Because neutrinos are nearly unaffected by matter, a neutrino beam could traverse directly through the earth from the transmission site to the submarine. A directional beam would allow confidential information to be passed only to the intended recipient. Neutrino communications would also be totally jam-proof. As an additional benefit, a neutrino message could be received in the deepest of waters, leaving a submarine less vulnerable to enemy attacks.
There's also research into using neutrinos as probes to detect things in the earth (oil, mineral deposits, etc). Different materials have different neutron absorption rate. Obviously this is pretty hard to pull off and expensive, but possible.
[deleted]
I've wondered the same about gravitons. Notwithstanding the need for likely-huge sensing equipment for the first N years of development...
It's not yet clear if gravitons exist at all.
I have a hard time imagining a particle associated with the curvature of spacetime.
the inability of current science to square relativity and its predictions of space-time with quantum mechanics is exactly the reason why we aren't sure, and one of the biggest open questions in physics.
I mean it could all be strings, or quantum gravity, or Wolfram's crazy graph theory automatons, or maybe something else entirely.
We don't know.
I mean it could all be strings, or quantum gravity, or Wolfram's crazy graph theory automatons, or maybe something else entirely.
We don't know.
I had a really hard time imagining a particle associated with mass (Higgs boson)
note that the Higgs is not responsible for all mass as is understood by a layperson. The Higgs field gives mass to subatomic particles but it doesn't translate directly into the mass of objects as we know them.
The mass of the three quarks (one up quark and two down quarks) making up a neutron is only about 1% of the mass of a neutron. The rest of the mass comes from strong nuclear force interactions via gluons which are themselves massless.
The mass of the three quarks (one up quark and two down quarks) making up a neutron is only about 1% of the mass of a neutron. The rest of the mass comes from strong nuclear force interactions via gluons which are themselves massless.
Doesn't this simply follow from the mass-energy equivalence (the energy being that of interaction with the Higgs in this case)? Not to say that said equivalence is intuitively obvious, of course.
Isn't that what the higgs is?
No. The higgs is a field that gives some elementary particles themselves (the W and Z bosons) mass, but doesn't necessarily say anything about gravity or how gravitic 'force' is transferred.
There was a lot of media hype about 'the god particle' that doesn't really translate into reality. I've said this in another comment, but if you add up the mass of the constituent quarks of a neutron, you get approximately 1% of a neutron's mass. The majority of the mass comes from interactions with strong nuclear force which are mediated by gluons, which are themselves massless.
There is no current agreed upon understanding of quantum gravity or if gravitons exist. I think the big contenders right now are String Theory (which seems to be having issues progressing in a way that is useful) and loop quantum gravity, but there are a lot more theories than that.
There was a lot of media hype about 'the god particle' that doesn't really translate into reality. I've said this in another comment, but if you add up the mass of the constituent quarks of a neutron, you get approximately 1% of a neutron's mass. The majority of the mass comes from interactions with strong nuclear force which are mediated by gluons, which are themselves massless.
There is no current agreed upon understanding of quantum gravity or if gravitons exist. I think the big contenders right now are String Theory (which seems to be having issues progressing in a way that is useful) and loop quantum gravity, but there are a lot more theories than that.
Rather amusingly this article is presently right below one on the arXiv project, but the phys.org article doesn't link to the arXiv version, so:
https://arxiv.org/abs/2105.06197
https://arxiv.org/abs/2105.06197
More information about FASER here:
https://faser.web.cern.ch/about-the-experiment/detector-desi...
https://faser.web.cern.ch/about-the-experiment/detector-desi...
What happens if a neutrino interacts with something?
Usually the neutrino will interact with a nucleus and what happens is the reverse of a beta decay, i.e. either a proton will be changed into a neutron or a neutron into a proton, with the emission of an electron or a positron.
So one atom will be converted into an atom of another element, which is a neighbor to it in the periodic table.
Because one neutral lepton goes in and one charged lepton goes out, you might say that the neutrino snatches an electric charge from a nucleus, transmuting it into the nucleus of another element. However this interaction happens extremely seldom. In most cases the neutrino passes by without any effects.
Nevertheless, there has been a proposal to generate extremely powerful neutrino beams, with which to destroy any hidden nuclear weapons.
So one atom will be converted into an atom of another element, which is a neighbor to it in the periodic table.
Because one neutral lepton goes in and one charged lepton goes out, you might say that the neutrino snatches an electric charge from a nucleus, transmuting it into the nucleus of another element. However this interaction happens extremely seldom. In most cases the neutrino passes by without any effects.
Nevertheless, there has been a proposal to generate extremely powerful neutrino beams, with which to destroy any hidden nuclear weapons.
So if we could force neutrino interactions at scale we could make any element we want in large quantities?
Using neutrinos is far less efficient than using gamma radiation or neutrons or high energy electrons or ions for transmutations.
The photons/neutrons/electrons/ions have a high probability of interaction with the target, while the neutrinos have a very low probability of interaction.
All the elements that do not exist in nature due to low lifetime have been produced by transmutation, but this can be done only for very small quantities at huge prices.
The photons/neutrons/electrons/ions have a high probability of interaction with the target, while the neutrinos have a very low probability of interaction.
All the elements that do not exist in nature due to low lifetime have been produced by transmutation, but this can be done only for very small quantities at huge prices.
Thanks for a great couple of replies. I'd just add that there are almost certainly more superheavy elements not thought to exist in nature which have yet to be produced artificially, but probably will be at some point.
... but which instantly decay. So not interesting.
There are definitely unstable superheavy elements that have never yet been produced, or at least detected, but the interesting prediction (widely accepted, but far from proven) is that there are some stable ones.
[0] https://en.wikipedia.org/wiki/Island_of_stability
[0] https://en.wikipedia.org/wiki/Island_of_stability
In some sense this is how particle collisions works. You collide something and with certain probability you get something else at the other end under the physical constraints. Probably you want to use bigger particles and lower energy though to go from subatomic to atomic/molecular scale. The laser ignition fusion experiments would be closer to that. (Mind the costs though :))
https://en.wikipedia.org/wiki/Stellar_nucleosynthesis
https://en.wikipedia.org/wiki/Stellar_nucleosynthesis
I imagine like a lot of the nuclear alchemy the cost is much higher than just getting the existing material you want.
But for something like a kardashev type 2 or 3 civilization with abundant energy, it would be trivial and saves time searching for and accumulating the material? It would also be conflict free.
Maybe we could start with processing nuclear waste though.
Having a big pile of random heavy elements can be a worse environmental issue.
[deleted]
That depends on the energy of the neutrino, for lower energies there will be some momentum exchange, but since neutrinos are extremely light, this may be neglected depending on your experimental setup.
At higher energies (>GeV) depending on the interaction type (whether a W-boson or a Z-boson is exchanged), a charged lepton comes out, which can be an electron, muon or tau (the tau decays very fast) and this is the same as the neutrino flavor. Or a hadronic shower if a nucleon is hit.
Of course it's always more complicated than that: for lower energies (sub-GeV) you get resonance scattering, where the nucleus will emit a meson (quark-anti-quark particle), or deep-inelastic scattering, where the nucleus is broken up and hadronic particles create a cascade of more particles.
Edit: see https://en.wikipedia.org/wiki/Particle_shower for more on these cascades. It's a bit bare-bone, I don't have a nice reference right now.
At higher energies (>GeV) depending on the interaction type (whether a W-boson or a Z-boson is exchanged), a charged lepton comes out, which can be an electron, muon or tau (the tau decays very fast) and this is the same as the neutrino flavor. Or a hadronic shower if a nucleon is hit.
Of course it's always more complicated than that: for lower energies (sub-GeV) you get resonance scattering, where the nucleus will emit a meson (quark-anti-quark particle), or deep-inelastic scattering, where the nucleus is broken up and hadronic particles create a cascade of more particles.
Edit: see https://en.wikipedia.org/wiki/Particle_shower for more on these cascades. It's a bit bare-bone, I don't have a nice reference right now.
Do we calculate the weight of all neutrinos in the Known mass of the universe? Or is that part of Dark Matter?
What is the mass of all the neutrinos in a cubic meter of “vacuum”?
What is the mass of all the neutrinos in a cubic meter of “vacuum”?
The mass of the neutrinos is not known with any reasonable precision.
It is known only that it is not likely to be zero (because the commonly accepted explanation for the so-called neutrino oscillations requires a non-null mass, even if there are alternative theories) and that it must be small because various experiments have determined some upper limits for the masses of the 3 kinds of neutrinos.
It is known only that it is not likely to be zero (because the commonly accepted explanation for the so-called neutrino oscillations requires a non-null mass, even if there are alternative theories) and that it must be small because various experiments have determined some upper limits for the masses of the 3 kinds of neutrinos.
You can tell the tale. It has happened to you!
That pesky sun doing it’s pesky fusion.
That pesky sun doing it’s pesky fusion.
[deleted]
The sophons are here
It’s always bugged me that science claims there are trillions of neutrinos going through me, yet can hardly detect them with a nearly trillion dollar machine and a doctorate. Then there’s dark energy, which just seems like a lame excuse for saying “we don’t know”.
Nobody says what goes through my body but me!
(I’m being funny, y’all! Happy holidays!)
Nobody says what goes through my body but me!
(I’m being funny, y’all! Happy holidays!)
The trillions of neutrinos going through you are low energy neutrinos from the sun. We've been able to detect those for decades, and with only moderately pricey technology.
The neutrinos in the article are high energy ones produced from proton collisions at the LHC. Although we have ways of producing neutrino beams from accelerators, the LHC is not set up for that, and these neutrinos are sparsely produced, incidentally to the high energy hadron collisions being produced there.
In any case, the LHC cost at least an order of magnitude less than a trillion dollars. And the FASER experiment in particular which runs parasitically on existing LHC infrastructure runs on a shoestring budget, largely privately funded.
The neutrinos in the article are high energy ones produced from proton collisions at the LHC. Although we have ways of producing neutrino beams from accelerators, the LHC is not set up for that, and these neutrinos are sparsely produced, incidentally to the high energy hadron collisions being produced there.
In any case, the LHC cost at least an order of magnitude less than a trillion dollars. And the FASER experiment in particular which runs parasitically on existing LHC infrastructure runs on a shoestring budget, largely privately funded.
Noobquestion(1)
It’s interesting that you class dark energy (the thing accelerating universal expansion) as, “We don’t know,” but don’t put gravity into that same category. They are both aspects of general relativity that we have failed to integrate with our other most successful fundamental theories, but if you asked an average person on the street I’m sure they’d put them in very different categories of understanding, as you did.
The thing with gravity is that it is kind of easy to detect, even for a layperson, while dark energy and dark matter haven't been detected at all, by anyone, but only used as mathematical devices to make indirect measurements of large scale structures align with our models.
So, it isn't only the "average man on the street" that thinks there are good reasons to put them in very different categories of understanding.
So, it isn't only the "average man on the street" that thinks there are good reasons to put them in very different categories of understanding.
Curiously... In the way dark matter has never been detected (no particle has been found), gravity has never been detected, and in the way gravity has been detected (through its influence on the trajectories of detectable matter), dark matter has been as well.
It’s a rather novel and very strange to say that something hasn’t been detected because you haven’t found a particle responsible for it, even though our whole existence and all our everyday experiences are grounded in it.
Gravity is the effect. It’s there. Whether you explain it with force carrying particles or the geometry of space time won’t change it.
Dark matter is one hypothetical explanation of an effect (or rather several). It’s possible to find another explanation for the same phenomena without changing the phenomena.
In other words, gravity and dark matter have very different ontological status.
Gravity is the effect. It’s there. Whether you explain it with force carrying particles or the geometry of space time won’t change it.
Dark matter is one hypothetical explanation of an effect (or rather several). It’s possible to find another explanation for the same phenomena without changing the phenomena.
In other words, gravity and dark matter have very different ontological status.
>In other words, gravity and dark matter have very different ontological status.
I get what you're saying, but you can make them the same again by transposing Dark Matter to Dark Matitation, by analogy to Gravitons->Gravitation.
I get what you're saying, but you can make them the same again by transposing Dark Matter to Dark Matitation, by analogy to Gravitons->Gravitation.
No, they are still not the same. If I understand you correctly, you are saying that Dark Matter would correspond to Gravitons. But that would just prove my point, because Gravitons is just a hypothetical explanation of gravity, in the same way as Dark matter is a hypothetical explanation of, e.g., the rotation profiles of galaxies.
(And here we have so far left out that the only reason Dark matter makes sense is because we are trying to not have to modify our current understanding of gravity.)
(And here we have so far left out that the only reason Dark matter makes sense is because we are trying to not have to modify our current understanding of gravity.)
Well, one reason dark matter is winning over modified gravity theories is that there seem to be some galaxies that don't have dark matter. So MOND needs more special pleading there, unless the observations are wrong.
The only thing I was arguing was that Gravity has a much more solid basis than Dark Matter. I certainly don't think I made it sound like I think MOND is more likely than Dark Matter (even though I confess that I still think the issue is far from settled).
Well, scientists would argue that general relativity (I.e. gravity the way we understand it now) does predict a lot of things really well.
Now, the problem is that its predictions fall apart at quantum scale and cosmological scale. Dark thingies are just a way to make the equations work at cosmological scale.
There's always modified gravity, which takes an alternative approach by changing the equations.
That's how they taught me 15 years ago, so give or take:-)
Now, the problem is that its predictions fall apart at quantum scale and cosmological scale. Dark thingies are just a way to make the equations work at cosmological scale.
There's always modified gravity, which takes an alternative approach by changing the equations.
That's how they taught me 15 years ago, so give or take:-)
Relevant xkcd: https://xkcd.com/1489/
The mouseover-text is the important bit: "Of these four forces, there's one we don't really understand." "Is it the weak force or the strong--" "It's gravity."
That's even though it's the one with the simplest equations.
The mouseover-text is the important bit: "Of these four forces, there's one we don't really understand." "Is it the weak force or the strong--" "It's gravity."
That's even though it's the one with the simplest equations.
> That's even though [gravity]'s the one with the simplest equations.
Aren't the equations for gravity non-linear, while the other 3 are linear?
Aren't the equations for gravity non-linear, while the other 3 are linear?
They're linear to the first-order, but everything is linear to first order by the definition of first order.
>Nobody says what goes through my body but me!
That's selfish! Mandatory trip to Chernobyl!
That's selfish! Mandatory trip to Chernobyl!
If you think science has you stomach untenable ideas, it's got nothing on what a lack of science will stick you with.
> seems like a lame excuse for saying “we don’t know”.
Dark matter/energy aren’t excuses, they’re labels for things that behave like matter and energy but whose nature is unknown.
Dark matter/energy aren’t excuses, they’re labels for things that behave like matter and energy but whose nature is unknown.
Well, dark matter at least to this layperson’s eye a label for observations that are most easily explained by matter, which is not quite the same as a “thing that behaves like matter”.
Just for the record, I’m not trying to be a jerk - I’m a layperson too. However, in science, it’s important to understand that some of the “I don’t know”s are so incredibly precise they’re not intended for the layperson. Rather, many are precise models used to help experts communicate.
Not exactly. Dark matter might reasonably considered a label for observations that are most easily explained by matter that only interacts with anything gravitationally. That’s really a quite strange property compared to all the other matter we see, but it does seem to explain a lot of things rather well.
In all seriousness, I found myself wondering about those numbers before; but consider that there's on the order of 10^27 atoms in your body. So, if we assume a trillion neutrinos in your body, that indicates that for each neutrino in your body, there are 10^15 atoms - that's one part per quadrillion! A machine capable of detecting neutrinos in your body would need to be _unimaginably_ sensitive, before even considering the intrinsic difficulty in detecting them due to low mass and neutral charge.
Look at it this way: Solar neutrinos carry away approximately 1% of the total fusion power output of the Sun. This works out to about 14 Watts per square meter at the distance of the Earth. The area of a human adult body front-on is about a square meter.
It's pretty easy to detect 14 W of typical forms of radiation at those scales! If it were light, it would be equivalent to the light put out by something like a laptop screen, spread out just a bit. You can see something like that with your eyes from a kilometer away!
It's pretty easy to detect 14 W of typical forms of radiation at those scales! If it were light, it would be equivalent to the light put out by something like a laptop screen, spread out just a bit. You can see something like that with your eyes from a kilometer away!
This is a great analogy, I'd never seen it translated into tangible terms like that before.
I remember reading that, at close enough range, the neutrino emissions from a supernova would be intense enough to be dangerous to structures made of ordinary matter, despite the weakness of their interactions, and that they would reach an observer earlier than other forms of radiation due to their ability to escape the collapsing star relatively unimpeded. Neutrinos would be the least of your problems if you were the observer of course.
As I was trying to find a source for this, I discovered there is a unit [1] for the amount of energy released by a supernova called the Foe, which seems apt (it's an acronym derived from 'ten to the power of Fifty-One-Ergs').
[1] https://en.wikipedia.org/wiki/Foe_(unit)
I remember reading that, at close enough range, the neutrino emissions from a supernova would be intense enough to be dangerous to structures made of ordinary matter, despite the weakness of their interactions, and that they would reach an observer earlier than other forms of radiation due to their ability to escape the collapsing star relatively unimpeded. Neutrinos would be the least of your problems if you were the observer of course.
As I was trying to find a source for this, I discovered there is a unit [1] for the amount of energy released by a supernova called the Foe, which seems apt (it's an acronym derived from 'ten to the power of Fifty-One-Ergs').
[1] https://en.wikipedia.org/wiki/Foe_(unit)
Perhaps "Lethal Neutrinos" https://what-if.xkcd.com/73/
I think my source was a book, but the XKCD is a better link! I think the book reference I had mind may have stated the effect in terms of force.
John Updike wrote a poem about the crassness of neutrinos:
http://www.physics.mcgill.ca/~crawford/PSG/PSG21/204_97_L21....
http://www.physics.mcgill.ca/~crawford/PSG/PSG21/204_97_L21....
Excellent. I give this 10^14 / 10^14.
The pedant in me wants to point out that they are now known to have some mass and do interact a bit, but this was written in 1960.
The pedant in me wants to point out that they are now known to have some mass and do interact a bit, but this was written in 1960.
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The physics anomaly no one talks about: What's up with those neutrinos?
https://www.youtube.com/watch?v=p118YbxFtGg (Sept 2021, 12 minutes)