14 ms·

Why the weak nuclear force is short range

374 points by sohkamyung 2y ago

somat 2y ago
There is an interesting video essay by the Huygens Optics channel where some simulations of these field effects are considered. Turning Waves Into Particles https://www.youtube.com/watch?v=tMP5Pbx8I4s https://www.youtube.com/watch?v=tMP5Pbx8I4s And if unfamiliar, that channel constantly delivers high quality thought provoking content on the nature of light.
- mmcnickle 2y ago
  One thing I'm not clear on when watching his videos is whether what he's describing is an established scientific interpretation, or his own thoughts as someone who has extensive knowledge on optical engineering (vs theory). Very enjoyable and thought provoking stuff though! Edit: spelling
  - mecsred 2y ago
    When he provides sources, then it's the first one, otherwise the second.
- pomian 2y ago
  That's great. Thanks. When you start watching it you think, it will be too long, but it gets better and better. Everything goes back to Einstein. YARH! Yet another rabbit hole! It's amazing we have any time left to do anything after reading HN.
- cellular 2y ago
  Nature of light? You May really like this: https://youtu.be/A-2XQQDD6QQ https://youtu.be/A-2XQQDD6QQ
randomtoast 2y ago
TLDR; It is short range primarily because the underlying fields (those of the W and Z bosons) are “stiff,” causing any disturbance to die off exponentially at distances much smaller than an atom’s diameter. In quantum language, that same stiffness manifests as the nonzero masses of the W and Z bosons, so their corresponding force does not effectively propagate over long distances—hence it appears “weak” and short-range.
- hammock 2y ago
  So it’s like a stiff spring /strut vs a loose one? Doesn’t a loose suspension dampen and stiff propagate quicker though?
- hammock 2y ago
  No one answered my question, but I figured out a point on a tightly stretched rubber sheet or drumhead is better analogy than a spring, because the tighter the material, the more force required and the less propagation
XorNot 2y ago
Urgh, I'm half way through this and I hate it. The problem is it's upfront that "X thing you learned is wrong" but is then freely introducing a lot of new ideas without grounding why they should be accepted - i.e. from sitting here knowing a little physics, what's the intuition which gets us to field "stiffness"? Stiff fields limit range, okay, but...why do we think those exist? The article just ends the explanation section and jumps to the maths, but fails to give any indication at all as to why field stiffness is a sensible idea to accept? Where does it come from? Why are non-stiff fields just travelling around a "c", except that we observe "c" to be the speed of light that they travel around? When we teach people about quantum mechanics and the uncertainty principle even at a pop-sci level, we do do it by pointing to the actual experiments which build the base of evidence, and the logical conflicts which necessitate deeper theory (i.e. you can take that idea, and build a predictive model which works and here's where they did that experiment). This just...gives no sense at all as to what this stiffness parameter actually is, why it turned up, or why there's what feels like a very coincidental overlap with the Uncertainty principle (i.e. is that intuition wrong because actually the math doesn't work out, is this just a different way of looking at it and there's no absolute source of truth or origin, what's happening?)
- andyferris 2y ago
  I agree this doesn't gel well with the pop-science approach. However, it is actually a similar approach to how De Broglie, Schrodinger, and others originally came up with their equations for quantum behavior - we start with special relativity and consider how a wave _must_ behave if its properties are going to be frame-independent, and follow the math from there. That part is equation (*), and the article leads with a bit of an analogy of how we might build a fully classical implemenation of it in an experiment (strings, possibly attached to a stiff rubber sheet) so we get some everyday intuition into the equation's behavior. So from my point of view, I found it very interesting. (What the article doesn't really get into is why certain fields might have S=0 and others not, what the intuition for the cause of that is, etc. It also presupposes you have bought into quantum field theory in the first place, and wish to consider the fundamental "wavicles" that would emerge from certain field equations, and that you aren't looking closely at the EM force or spin or any other number of things normally encountered before learning about the weak force).
Timwi 2y ago
What makes me skeptical here is that the author claims that fields have a property that is necessary to explain this, and yet physicists have not given that property a name, so he has to invent one (“stiffness”). If the quantity appears in equations, I find it hard to believe that it was never given a name. Can anyone in the field of physics elucidate?
- sigmoid10 2y ago
  The author isn't inventing anything. He's just dumbing it down in an extreme way so that non-physicists could have the faintest hope of understanding it. Wich seems odd, because if you actually want to understand any of this you should prepare to spend two or three years in university level math classes first. The truth is that in reality all this is actually a lot more complex. In the Higgs field (or any simple scalar field for that matter) for example, there is a free parameter that we could immediately identify as "mass" in the way described in the article. But weirdly enough, this is not the mass of the Higgs boson (because of some complicated shenanigans). Even more counterintuitive, fermionic (aka matter) fields and massive bosonic fields (i.e. the W and Z bosons mentioned in the article) in the Standard Model don't have any mass term by themselves at all. They only get something that looks (and behaves) like a mass term from their coupling to the Higgs field. So it's the "stiffness" of the Higgs field (highly oversimplified) that gives rise to the "stiffness" of the other fields through complex interactions governed by symmetries. And to put it to the extreme, the physical mass you can measaure in a laboratory is something that depends on the energy scale at which you perform your experiments. So even if you did years of math and took an intro to QFT class and finally think you begin to understand all this, Renormalization Group Theory comes in kicks you back down. If you go really deep, you'll run into issues like Landau Poles and Quantum Triviality and the very nature of what perturbation theory can tell us about reality after all. In the end you will be two thirds through grad school by the time you can comfortably discuss any of this. The origin of mass is a really convoluted construct and these low-level discussions of it will always paint a tainted picture. If you want the truth, you can only trust the math.
  - azalemeth 2y ago
    I think perhaps the 'maths' at the bottom is a bit of a retelling of the Yukawa potential which you can get in a "relatively understandable" way from the Klein-Gordon equation. However, the KG equation is very very wrong! Perhaps an approach trying to actually explain the Feynman propagators would be more helpful? Either way, I agree that if someone wanted to understand this all properly it requires a university education + years of postgrad exposure to the delights of QED / electroweak theory. If anyone here wants a relatively understandable deep dive, my favourite books are Quantum Field Theory for the Gifted Amateur [aka graduate student] by Stephen Blundell [who taught me] and Tom Lancester [his former graduate student], and also Quarks and Leptons by Halzel and Martin. It is not a short road.
brabel 2y ago
> Only stiff fields can have standing waves in empty space, which in turn are made from “particles” that are stationary and vibrating. And so, the very existence of a “particle” with non-zero mass is a consequence of the field’s stiffness. It's really difficult to reconcile "standing waves in empty space" with "stiff fields". If the space is truly empty, then the field seems to be an illusion? If we think about fields as the very old concept of aether, then it actually makes more intuitive sense. Stiffness then becomes simply the viscosity of the aether. But I don't think this is where this article is trying to get us!!
- mjburgess 2y ago
  fields are a non-mechanical aether, more precisely they are lorentz invarient (ie., their motion is the same for all observers)
- keepamovin 2y ago
  And if you can hop from each standing wave node to the next, you can teleport, or move ridiculously fast by moving discretely instead of continuously. What if you could tune the wavelength of these standing waves with particles stationary and vibrating? I like the speaker on water / styrofoam particle demonstration of standing waves.
  - hammock 2y ago
    Or change the frequency of the wave you are standing on (or those around you, I’m not sure which) and move forward like an inchworm I believe this is not dissimilar to the mechanics suggested by the ZPE/antigravity people like Ashton Forbes
Veronika88 2y ago
[flagged]
jagrsw 2y ago
If we wanted to model the universe as a set of equations or a cellular automaton, how complex would that program be? Could a competent software engineer, even without knowing the fundamental origins of things like particle masses or the fine-structure constant, capture all known fundamental interactions in code? I guess I'm trying to figure out the complexity of the task of universe creation, assuming the necessary computational power exists. For example, could it be a computer science high school project for the folks in the parent universe (simulation hypothesis). I know that's a tough question :)
- dmos62 2y ago
  Stephen Wolfram has been taking a stab at it. Researching fundamental physics via computational exploration is how I'd put it. https://www.wolframphysics.org/ https://www.wolframphysics.org/
  - cjfd 2y ago
    He is basically a crackpot. Any attempt at fundamental physics that doesn't take quantum mechanics into account is.... uhm.... how to put this.... 'questionable'.
    - russdill 2y ago
      That really seems to be mischaracterizing his work. The idea is that the quantum effects we see will eventually emerge. Most people in the field don't think his research will be fruitful, but that doesn't make him a crack pot
      - momoschili 2y ago
        most people in the field believe his research isn't even capable of being wrong
    - dmos62 2y ago
      Someone seems to say something demeaning like that about him whenever he comes up, and I don't really know why. Which is fine, maybe it's a subjective thing. For what it's worth, the few times I read something of his, I loved it.
at_a_remove 2y ago
How I learned it, as a mere undergrad, was that the mass of the virtual particle for the field in question determined exactly how long it could exist, just by the uncertainty principle -- much like the way the virtual particles drive Hawking radiation. In short, a massive virtual particle can exist only briefly before The Accountant comes looking to balance the books. And if you give it a speed of c, it can travel only so far during its brief existence before the books get balanced. And therefore the range of the force is determined by the mass of the force carrier virtual particle. There's probably some secondary and tertiary "loops" as the virtual particle possibly decays during its brief existence, influencing the math a little further, but that is beyond me.
- not2b 2y ago
  And the article we are discussing explains why this is incorrect.
nyc111 2y ago
"For the subtleties of different meanings of “mass”, see chapters 5-8 of my book.]" Isn't this called "equivocation" in logic?
mtreis86 2y ago
The top of fig 3 doesn't accurately represent a string pulled down in the middle. A string pulled down in the middle would have no curve to it in the legs unless some force is acting on it, it would look like a V.
- seeekr 2y ago
  To me it seems like it's depicting a situation where the string hasn't been pulled fully, so some of its slack hasn't straightened out into the otherwise resulting triangle yet.
SpaceManNabs 2y ago
This particular article has a prelude on the same website https://profmattstrassler.com/2025/01/10/no-the-short-range-of-the-weak-nuclear-force-isnt-due-to-quantum-physics/ https://profmattstrassler.com/2025/01/10/no-the-short-range-...
halyconWays 2y ago
PSA: it's "fib," not "phib"
- not2b 2y ago
  No, his use is intentional. It's a portmanteau for "physics fib".
- deleted 2y ago
  [deleted]
metacritic12 2y ago
Doesn't this "explanation" just shift the question to what is stiffness? Like it refactored the question but didn't actually explain it. Previously, we had statement "the weak force is short range". In order to explain it, we had to invent a new concept "stiffness" that is treated as a primitive and not explained in terms of other easy primitives, and then we get to "accurately" say that the weak force is short due to stiffness. I grant the OP that stiffness might be hard to explain, but then why not just say "the weak force is short range -- and just take that as an axiom for now".
- pishpash 2y ago
  Because you may get something else out of stiffness besides this explanation? Usually that's how a level deeper explanation works.
- drdec 2y ago
  If you read far enough into the math-y explanations, stiffness is a quantity in the equations. That makes it more than a hand waving explanation in my book.
- ajkjk 2y ago
  I think it's a big improvement. Stiffness is something you can picture directly, so the data -> conclusions inference "stiffness" -> "mass and short range" follows directly from the facts you know and your model of what they mean. Whereas "particles have mass" -> "short range" requires someone also telling you how the inference step (the ->) works, and you just memorize this as a fact: "somebody told me that mass implies short range". You can't do anything with that (without unpacking it into the math), and it's much harder to pattern-match to other situations, especially non-physical ones. It seems to me like the right criteria for a good model is: * there are as few non-intuitable inferences as possible, so most conclusions can be derived from a small amount of knowledge * and of course, inferences you make with your intuition should not be wrong (I suppose any time you approximate a model with a simpler one---such as the underlying math with a series of atomic notions, as in this case---you have done some simplification and now you might make wrong inferences. But a lot of the wrongness can be "controlled" with just a few more atoms. For instance "you can divide two numbers, unless the denominator is zero" is such a control: division is intuitive, but there's one special case, so you memorize the general rule plus the case, and that's still a good foundation for doing inference with)
bnetd 2y ago
As an aside, is there conclusive evidence to say that no aether exists, or are we just saying it doesn't exist because a handful of tests were conducted to match what we thought this aether would behave like and the tests came back negative?
- aidenn0 2y ago
  For a strict enough definition of "conclusive," there is never conclusive evidence that something doesn't exist. On top of that, if we find something that behaves nothing like what people meant when they said aether, then is it really aether?
- LegionMammal978 2y ago
  Lorentz formulated his ideas in terms of a motionless aether. But his aether theory yielded predictions identical to special relativity, so later physicists ditched his interpretation in favor of Einstein's theory that didn't need an undetectable global reference frame. Overall, we can't really have 'conclusive evidence' against any mechanism, as long as our observations might possibly be simulated on top of that mechanism. So as far as evidence goes, 'what really exists' might be higher-dimensional strings, or cellular automata, or turtles all the way down, or whatever. Instead, physics has some number of models (either complementary or competing) that people find compelling, and mechanisms on top of those models to explain our observations. If you did come up with a modern aether theory, you'd have to come up with a mechanism on top of it to explain all the relativistic effects we've observed.
- pdonis 2y ago
  We say the "aether" as it was originally conceptualized in the 19th century doesn't exist for the same reason we say that Russell's teapot or Carl Sagan's invisible dragon in the garage doesn't exist: we have a model of the world that makes all the same predictions without it, so it gets scraped right off by Occam's Razor.
- akomtu 2y ago
  Magnetic field is that aether.
- 2y ago
aidenn0 2y ago
It seems to me that there is a 1:1 correlation between mass of virtual particle and field stiffness. Given that fact, why isn't it equally correct to say "The field stiffness is caused by the mass of the virtual particle" and "The virtual particle necessarily has mas because the field is stiff" The author states that "it is short range because the particles that “mediate” the force, the W and Z bosons, have mass;" is misleading as to causality, but I missed the part where they showed how/why it was misleading.
- sojuz151 2y ago
  Because in a classical theory, where there are no particles, there is still the same short range potential.
  - aidenn0 2y ago
    This arises from a parameter in the elementary field equation. If that parameter is non-zero than it is both true that the field is stiff and it must be mediated by a particle with non-zero rest mass. This says nothing about causality.
    - scotty79 2y ago
      Correct. The author explains how both limited range and particles ability to have energy even at rest comes from "stiffness" (which is how he decided to call this parameter you talk about, in order to convey physics to laymen).
nimish 2y ago
This is a lot of words to say that the field oscillations (i.e., particles) require very high energy. This shows up as the mass-(energy) of the particle, or stiffness of the field; take your pick. Whether you call that stiffness or mass is a little beside the point IMO -- it shows up in the Yukawa force as an exponential dependence on that parameter which means the force quickly decays to zero unless the parameter is 0.
- scotty79 2y ago
  All of the explanations like the one you provided sounds like code comments in the style: x = 2 # sets x to two What he wrote is the first attempt I've seen of making actually informative comment about the purpose and intent instead of just regurgitating math verbatim but with words instead.
  - nimish 2y ago
    > regurgitating math verbatim but with words instead Where in my comment is there any math? It's all physical concepts. No mathematics at all. Because the purpose and intent of my post was to point out that the role mass plays is identical to that of stiffness in other contexts. That's it, and he takes a very circuitous route to pointing that out. It's like the opposite of what you described. If you don't know what "mass" and "stiffness" are you should probably understand those before attempting to understand quantum field theory. It's not condescension. The analogy holds only if you really understand both concepts. The algebra is beside the point.
    - scotty79 2y ago
      Here's math, just read out loud: "it shows up in the Yukawa force as an exponential dependence on that parameter which means the force quickly decays to zero unless the parameter is 0" It tells nothing to people who don't know the equation you are talking about and tells nothing new to people who know it.
bawana 2y ago
The effect of stiffness can also be represented by stretchability of the string. Picking up a string with a free end will result in the same shape described by adding stiffness. A fanciful analogy might be a chain of springs with constant k2 where each spring junction is anchored to the ground with a spring with constant k1. If k2>>k1 the entire spring chain lifts in a gentle arc when a spring is lifted. If k1>>k2, only the springs near the pulling point really stretch and displace. It’s these kinds of simple analogies that engage our intuition. I still however cannot envision a mechanical analogy to demonstrate wavicles.
gweinberg 2y ago
One thing that confused me at the very beginning is, the author says the weak force is weak because it is short range. But the strong force is also short range.
- lilyball 2y ago
  The weak force is weak not because it has "short range" but because its range "dies off at distances ten million times smaller than an atom".
- MathMonkeyMan 2y ago
  The strong force is short range for a different reason. It's called [confinement][1]. The strong force gets stronger as you pull color charges apart. At some point the energy is so high that it's very likely that corresponding matching-color particles will exist, and so now there two pairs of close charges, instead of one pair of far charges. [1]: https://en.wikipedia.org/wiki/Color_confinement https://en.wikipedia.org/wiki/Color_confinement
JumpCrisscross 2y ago
> Google’s AI, for instance, and also here — that the virtual particles with mass actually “decay“ Do virtual particles decay?
vonneumannstan 2y ago
The real answer is we don't know or otherwise some kind of anthropic argument, i.e. the weak force has the range it does becuase otherwise we wouldn't have this kind of universe with people in it pondering why the weak force is the way it is. Seems generally unhelpful to say 'the weak force is short range because it's field is stiffer!' When you can then immediately say 'well why is the weak force's field stiffer?'
- atoav 2y ago
  Got you, but I am unsure if moving to the next question isn't a success as well. You understood a thing and move on, rinse and repeat. Or: consider where science would be had it operated under your proposed maxime for the past 3 centuries.
  - vonneumannstan 2y ago
    Not sure I get this because we have no deeper understanding using the example I gave. I.e. The weak force is short range because it's field is stiffer -> the weak force's field is stiffer because it is more oblong -> the weak force's field is more oblong because it has more sparkles -> it has more sparkles because it ha slower mushiness -> it has more mushiness because ...etc. We haven't gained anything in that sequence. I don't think we can answer fundamental questions like this. The fine structure constant is the value it is because without that value we can't have a universe like this. Maybe in some multiverse system the physical laws and constants we know are fluid and can take different values in different universes but in our universe simply because of observation selection effects they can only be what they are.
    - atoav 2y ago
      Thw piano string produces a higer torque because it is shorter does not answer you why it is shorter or how waves travel exactly within it, but it sure as hell would be required knowledge to start researching beyond that first observation. > The weak force is short range because it's field is stiffer. May seem like a simple redirection that could go on forever, but we learned that fields can be stiffer, which probably wasn't all that clear. Now we can observe all other forces and look how their fields vary in terms of stiffness — a parameter we might not have thought about before. And by looking in those other places we might find a clue on how to shape an experiment that allows us to vary the stiffness. That could already have useful applications, but also lead to answering the question why some forces have stiffer fields than others.
dschleef 2y ago
This article goes to great contortions to avoid talking about electroweak theory or spontaneous symmetry breaking, both of which have decent Wikipedia articles, and are crucial to understanding what's going on here. Spontaneous symmetry breaking of the electroweak interaction and the Higgs mechanism is the reason _why_ the W and Z have mass. The article throws up a "who knows?" at this. When you write down the field equations for a massive boson field, you get an additional m^2 term in the denominator of the propagator, which contributes a e^(-r/m) term to the interaction force at low energy, such as the decay of a neutron or a weak-mediated nuclear decay. Is there an ELI5 version of this? I think the article tries, and it's always cool to see physics described from a different vantage point. My ELI5 version would be: fields with a massive gauge boson are "dragged down" in energy by the mass of the boson, so interactions propagate as if they have negative energy. What does a negative energy wave propagation look like? Similar negative energy wave propagations in physics are evanescent waves and electron tunneling, both of which have exponential drop-off terms, so it makes sense to see an exponential factor in massive boson interactions.
nyc111 2y ago
"In a quantum world such as ours, the field’s waves are made from indivisible tiny waves, which for historical reasons we call “particles.” Despite their name, these objects aren’t little dots; see Fig. 8." Does anyone know when physicists realized that the world is not made of indivisible units called "particles" but waves? Is there a specific experiment or are we talking about the results of many experiments?
- T-A 2y ago
  https://en.wikipedia.org/wiki/Wave%E2%80%93particle_duality https://en.wikipedia.org/wiki/Wave%E2%80%93particle_duality
  - nyc111 2y ago
    But he is not talking about wave particle duality. He explicitly states that it is not helpful "to imagine them as both wave and particle." He calls waves with very small amplitude "particles" (for historical reasons). So, according to this picture the building blocks of the universe are waves. It makes no difference if physicists choose to call a wave "particle". Calling a wave particle does not make the wave a particle.
    - T-A 2y ago
      > He explicitly states that it is not helpful "to imagine them as both wave and particle." Where? I can't find that quote in the article. > He calls waves with very small amplitude "particles" (for historical reasons). The closest thing I see is In a quantum world such as ours, the field’s waves are made from indivisible tiny waves, which for historical reasons we call “particles.” Note the "indivisible" part. That's not how waves work in your everyday experience. The common understanding of "wave" is based on classical physics, where waves can be scaled up or down arbitrarily. But here you have "waves" which can only get so small, but no smaller, which he then goes on to parenthetically suggest calling "wavicles". Is coining a new word which is literally a combination of "wave" and "particle" not a way "to imagine them as both wave and particle"?
the__alchemist 2y ago
>NOTICE THERE IS NO QUANTUM PHYSICS IN THIS DISCUSSION! The short range of the field is a “classical” effect; i.e., it can be understood without any knowledge of the underlying role of quantum physics in our universe. It arises straightforwardly from ordinary field concepts and an ordinary differential equation. Nothing uncertain about it. It's interesting to me how fuzzy the definition of quantum physics is. For example, I've seen the description of particles as described by a wave function (e.g. electron position and momentum in an atom) labeled as a quantum phenomenon, but have also heard it, as in this quote, as classical, since it's defined by a differential equation; a "classical" wave. In that view, quantum only enters the model when modelling exchange effects, spin, fermion states etc. With the former definition, as in the article, you see descriptions of the wave nature of matter, replete with Planck's constant, complex wave function representations etc described as classical.
MagicMoonlight 2y ago
Stiffness just seems to be rewriting mass as a different term. Only things with mass have stiffness, stiffness is exactly proportional to mass, light isn’t stiff…
deleted 2y ago
[deleted]
xyzzy9563 2y ago
The reason is because of the anthropic principle. If it wasn't short range, we probably wouldn't exist and there would be no consciousness to observe it.

374 points by sohkamyung 2y ago

There is an interesting video essay by the Huygens Optics channel where some simulations of these field effects are considered. Turning Waves Into Particles https://www.youtube.com/watch?v=tMP5Pbx8I4s https://www.youtube.com/watch?v=tMP5Pbx8I4s And if unfamiliar, that channel constantly delivers high quality thought provoking content on the nature of light.

mmcnickle 2y ago
One thing I'm not clear on when watching his videos is whether what he's describing is an established scientific interpretation, or his own thoughts as someone who has extensive knowledge on optical engineering (vs theory). Very enjoyable and thought provoking stuff though! Edit: spelling
- mecsred 2y ago
  When he provides sources, then it's the first one, otherwise the second.
pomian 2y ago
That's great. Thanks. When you start watching it you think, it will be too long, but it gets better and better. Everything goes back to Einstein. YARH! Yet another rabbit hole! It's amazing we have any time left to do anything after reading HN.
cellular 2y ago
Nature of light? You May really like this: https://youtu.be/A-2XQQDD6QQ https://youtu.be/A-2XQQDD6QQ

randomtoast 2y ago

TLDR; It is short range primarily because the underlying fields (those of the W and Z bosons) are “stiff,” causing any disturbance to die off exponentially at distances much smaller than an atom’s diameter. In quantum language, that same stiffness manifests as the nonzero masses of the W and Z bosons, so their corresponding force does not effectively propagate over long distances—hence it appears “weak” and short-range.

hammock 2y ago
So it’s like a stiff spring /strut vs a loose one? Doesn’t a loose suspension dampen and stiff propagate quicker though?
hammock 2y ago
No one answered my question, but I figured out a point on a tightly stretched rubber sheet or drumhead is better analogy than a spring, because the tighter the material, the more force required and the less propagation

XorNot 2y ago

Urgh, I'm half way through this and I hate it. The problem is it's upfront that "X thing you learned is wrong" but is then freely introducing a lot of new ideas without grounding why they should be accepted - i.e. from sitting here knowing a little physics, what's the intuition which gets us to field "stiffness"? Stiff fields limit range, okay, but...why do we think those exist? The article just ends the explanation section and jumps to the maths, but fails to give any indication at all as to why field stiffness is a sensible idea to accept? Where does it come from? Why are non-stiff fields just travelling around a "c", except that we observe "c" to be the speed of light that they travel around? When we teach people about quantum mechanics and the uncertainty principle even at a pop-sci level, we do do it by pointing to the actual experiments which build the base of evidence, and the logical conflicts which necessitate deeper theory (i.e. you can take that idea, and build a predictive model which works and here's where they did that experiment). This just...gives no sense at all as to what this stiffness parameter actually is, why it turned up, or why there's what feels like a very coincidental overlap with the Uncertainty principle (i.e. is that intuition wrong because actually the math doesn't work out, is this just a different way of looking at it and there's no absolute source of truth or origin, what's happening?)

andyferris 2y ago
I agree this doesn't gel well with the pop-science approach. However, it is actually a similar approach to how De Broglie, Schrodinger, and others originally came up with their equations for quantum behavior - we start with special relativity and consider how a wave _must_ behave if its properties are going to be frame-independent, and follow the math from there. That part is equation (*), and the article leads with a bit of an analogy of how we might build a fully classical implemenation of it in an experiment (strings, possibly attached to a stiff rubber sheet) so we get some everyday intuition into the equation's behavior. So from my point of view, I found it very interesting. (What the article doesn't really get into is why certain fields might have S=0 and others not, what the intuition for the cause of that is, etc. It also presupposes you have bought into quantum field theory in the first place, and wish to consider the fundamental "wavicles" that would emerge from certain field equations, and that you aren't looking closely at the EM force or spin or any other number of things normally encountered before learning about the weak force).

Timwi 2y ago

What makes me skeptical here is that the author claims that fields have a property that is necessary to explain this, and yet physicists have not given that property a name, so he has to invent one (“stiffness”). If the quantity appears in equations, I find it hard to believe that it was never given a name. Can anyone in the field of physics elucidate?

sigmoid10 2y ago
The author isn't inventing anything. He's just dumbing it down in an extreme way so that non-physicists could have the faintest hope of understanding it. Wich seems odd, because if you actually want to understand any of this you should prepare to spend two or three years in university level math classes first. The truth is that in reality all this is actually a lot more complex. In the Higgs field (or any simple scalar field for that matter) for example, there is a free parameter that we could immediately identify as "mass" in the way described in the article. But weirdly enough, this is not the mass of the Higgs boson (because of some complicated shenanigans). Even more counterintuitive, fermionic (aka matter) fields and massive bosonic fields (i.e. the W and Z bosons mentioned in the article) in the Standard Model don't have any mass term by themselves at all. They only get something that looks (and behaves) like a mass term from their coupling to the Higgs field. So it's the "stiffness" of the Higgs field (highly oversimplified) that gives rise to the "stiffness" of the other fields through complex interactions governed by symmetries. And to put it to the extreme, the physical mass you can measaure in a laboratory is something that depends on the energy scale at which you perform your experiments. So even if you did years of math and took an intro to QFT class and finally think you begin to understand all this, Renormalization Group Theory comes in kicks you back down. If you go really deep, you'll run into issues like Landau Poles and Quantum Triviality and the very nature of what perturbation theory can tell us about reality after all. In the end you will be two thirds through grad school by the time you can comfortably discuss any of this. The origin of mass is a really convoluted construct and these low-level discussions of it will always paint a tainted picture. If you want the truth, you can only trust the math.
- azalemeth 2y ago
  I think perhaps the 'maths' at the bottom is a bit of a retelling of the Yukawa potential which you can get in a "relatively understandable" way from the Klein-Gordon equation. However, the KG equation is very very wrong! Perhaps an approach trying to actually explain the Feynman propagators would be more helpful? Either way, I agree that if someone wanted to understand this all properly it requires a university education + years of postgrad exposure to the delights of QED / electroweak theory. If anyone here wants a relatively understandable deep dive, my favourite books are Quantum Field Theory for the Gifted Amateur [aka graduate student] by Stephen Blundell [who taught me] and Tom Lancester [his former graduate student], and also Quarks and Leptons by Halzel and Martin. It is not a short road.

brabel 2y ago

> Only stiff fields can have standing waves in empty space, which in turn are made from “particles” that are stationary and vibrating. And so, the very existence of a “particle” with non-zero mass is a consequence of the field’s stiffness. It's really difficult to reconcile "standing waves in empty space" with "stiff fields". If the space is truly empty, then the field seems to be an illusion? If we think about fields as the very old concept of aether, then it actually makes more intuitive sense. Stiffness then becomes simply the viscosity of the aether. But I don't think this is where this article is trying to get us!!

mjburgess 2y ago
fields are a non-mechanical aether, more precisely they are lorentz invarient (ie., their motion is the same for all observers)
keepamovin 2y ago
And if you can hop from each standing wave node to the next, you can teleport, or move ridiculously fast by moving discretely instead of continuously. What if you could tune the wavelength of these standing waves with particles stationary and vibrating? I like the speaker on water / styrofoam particle demonstration of standing waves.
- hammock 2y ago
  Or change the frequency of the wave you are standing on (or those around you, I’m not sure which) and move forward like an inchworm I believe this is not dissimilar to the mechanics suggested by the ZPE/antigravity people like Ashton Forbes

Veronika88 2y ago

[flagged]

jagrsw 2y ago

If we wanted to model the universe as a set of equations or a cellular automaton, how complex would that program be? Could a competent software engineer, even without knowing the fundamental origins of things like particle masses or the fine-structure constant, capture all known fundamental interactions in code? I guess I'm trying to figure out the complexity of the task of universe creation, assuming the necessary computational power exists. For example, could it be a computer science high school project for the folks in the parent universe (simulation hypothesis). I know that's a tough question :)

dmos62 2y ago
Stephen Wolfram has been taking a stab at it. Researching fundamental physics via computational exploration is how I'd put it. https://www.wolframphysics.org/ https://www.wolframphysics.org/
- cjfd 2y ago
  He is basically a crackpot. Any attempt at fundamental physics that doesn't take quantum mechanics into account is.... uhm.... how to put this.... 'questionable'.
  - russdill 2y ago
    That really seems to be mischaracterizing his work. The idea is that the quantum effects we see will eventually emerge. Most people in the field don't think his research will be fruitful, but that doesn't make him a crack pot
    - momoschili 2y ago
      most people in the field believe his research isn't even capable of being wrong
  - dmos62 2y ago
    Someone seems to say something demeaning like that about him whenever he comes up, and I don't really know why. Which is fine, maybe it's a subjective thing. For what it's worth, the few times I read something of his, I loved it.

at_a_remove 2y ago

How I learned it, as a mere undergrad, was that the mass of the virtual particle for the field in question determined exactly how long it could exist, just by the uncertainty principle -- much like the way the virtual particles drive Hawking radiation. In short, a massive virtual particle can exist only briefly before The Accountant comes looking to balance the books. And if you give it a speed of c, it can travel only so far during its brief existence before the books get balanced. And therefore the range of the force is determined by the mass of the force carrier virtual particle. There's probably some secondary and tertiary "loops" as the virtual particle possibly decays during its brief existence, influencing the math a little further, but that is beyond me.

not2b 2y ago
And the article we are discussing explains why this is incorrect.

nyc111 2y ago

"For the subtleties of different meanings of “mass”, see chapters 5-8 of my book.]" Isn't this called "equivocation" in logic?

mtreis86 2y ago

The top of fig 3 doesn't accurately represent a string pulled down in the middle. A string pulled down in the middle would have no curve to it in the legs unless some force is acting on it, it would look like a V.

seeekr 2y ago
To me it seems like it's depicting a situation where the string hasn't been pulled fully, so some of its slack hasn't straightened out into the otherwise resulting triangle yet.

SpaceManNabs 2y ago

This particular article has a prelude on the same website https://profmattstrassler.com/2025/01/10/no-the-short-range-of-the-weak-nuclear-force-isnt-due-to-quantum-physics/ https://profmattstrassler.com/2025/01/10/no-the-short-range-...

halyconWays 2y ago

PSA: it's "fib," not "phib"

not2b 2y ago
No, his use is intentional. It's a portmanteau for "physics fib".
deleted 2y ago
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metacritic12 2y ago

Doesn't this "explanation" just shift the question to what is stiffness? Like it refactored the question but didn't actually explain it. Previously, we had statement "the weak force is short range". In order to explain it, we had to invent a new concept "stiffness" that is treated as a primitive and not explained in terms of other easy primitives, and then we get to "accurately" say that the weak force is short due to stiffness. I grant the OP that stiffness might be hard to explain, but then why not just say "the weak force is short range -- and just take that as an axiom for now".

pishpash 2y ago
Because you may get something else out of stiffness besides this explanation? Usually that's how a level deeper explanation works.
drdec 2y ago
If you read far enough into the math-y explanations, stiffness is a quantity in the equations. That makes it more than a hand waving explanation in my book.
ajkjk 2y ago
I think it's a big improvement. Stiffness is something you can picture directly, so the data -> conclusions inference "stiffness" -> "mass and short range" follows directly from the facts you know and your model of what they mean. Whereas "particles have mass" -> "short range" requires someone also telling you how the inference step (the ->) works, and you just memorize this as a fact: "somebody told me that mass implies short range". You can't do anything with that (without unpacking it into the math), and it's much harder to pattern-match to other situations, especially non-physical ones. It seems to me like the right criteria for a good model is: * there are as few non-intuitable inferences as possible, so most conclusions can be derived from a small amount of knowledge * and of course, inferences you make with your intuition should not be wrong (I suppose any time you approximate a model with a simpler one---such as the underlying math with a series of atomic notions, as in this case---you have done some simplification and now you might make wrong inferences. But a lot of the wrongness can be "controlled" with just a few more atoms. For instance "you can divide two numbers, unless the denominator is zero" is such a control: division is intuitive, but there's one special case, so you memorize the general rule plus the case, and that's still a good foundation for doing inference with)

bnetd 2y ago

As an aside, is there conclusive evidence to say that no aether exists, or are we just saying it doesn't exist because a handful of tests were conducted to match what we thought this aether would behave like and the tests came back negative?

aidenn0 2y ago
For a strict enough definition of "conclusive," there is never conclusive evidence that something doesn't exist. On top of that, if we find something that behaves nothing like what people meant when they said aether, then is it really aether?
LegionMammal978 2y ago
Lorentz formulated his ideas in terms of a motionless aether. But his aether theory yielded predictions identical to special relativity, so later physicists ditched his interpretation in favor of Einstein's theory that didn't need an undetectable global reference frame. Overall, we can't really have 'conclusive evidence' against any mechanism, as long as our observations might possibly be simulated on top of that mechanism. So as far as evidence goes, 'what really exists' might be higher-dimensional strings, or cellular automata, or turtles all the way down, or whatever. Instead, physics has some number of models (either complementary or competing) that people find compelling, and mechanisms on top of those models to explain our observations. If you did come up with a modern aether theory, you'd have to come up with a mechanism on top of it to explain all the relativistic effects we've observed.
pdonis 2y ago
We say the "aether" as it was originally conceptualized in the 19th century doesn't exist for the same reason we say that Russell's teapot or Carl Sagan's invisible dragon in the garage doesn't exist: we have a model of the world that makes all the same predictions without it, so it gets scraped right off by Occam's Razor.
akomtu 2y ago
Magnetic field is that aether.
2y ago

aidenn0 2y ago

It seems to me that there is a 1:1 correlation between mass of virtual particle and field stiffness. Given that fact, why isn't it equally correct to say "The field stiffness is caused by the mass of the virtual particle" and "The virtual particle necessarily has mas because the field is stiff" The author states that "it is short range because the particles that “mediate” the force, the W and Z bosons, have mass;" is misleading as to causality, but I missed the part where they showed how/why it was misleading.

sojuz151 2y ago
Because in a classical theory, where there are no particles, there is still the same short range potential.
- aidenn0 2y ago
  This arises from a parameter in the elementary field equation. If that parameter is non-zero than it is both true that the field is stiff and it must be mediated by a particle with non-zero rest mass. This says nothing about causality.
  - scotty79 2y ago
    Correct. The author explains how both limited range and particles ability to have energy even at rest comes from "stiffness" (which is how he decided to call this parameter you talk about, in order to convey physics to laymen).

nimish 2y ago

This is a lot of words to say that the field oscillations (i.e., particles) require very high energy. This shows up as the mass-(energy) of the particle, or stiffness of the field; take your pick. Whether you call that stiffness or mass is a little beside the point IMO -- it shows up in the Yukawa force as an exponential dependence on that parameter which means the force quickly decays to zero unless the parameter is 0.

scotty79 2y ago
All of the explanations like the one you provided sounds like code comments in the style: x = 2 # sets x to two What he wrote is the first attempt I've seen of making actually informative comment about the purpose and intent instead of just regurgitating math verbatim but with words instead.
- nimish 2y ago
  > regurgitating math verbatim but with words instead Where in my comment is there any math? It's all physical concepts. No mathematics at all. Because the purpose and intent of my post was to point out that the role mass plays is identical to that of stiffness in other contexts. That's it, and he takes a very circuitous route to pointing that out. It's like the opposite of what you described. If you don't know what "mass" and "stiffness" are you should probably understand those before attempting to understand quantum field theory. It's not condescension. The analogy holds only if you really understand both concepts. The algebra is beside the point.
  - scotty79 2y ago
    Here's math, just read out loud: "it shows up in the Yukawa force as an exponential dependence on that parameter which means the force quickly decays to zero unless the parameter is 0" It tells nothing to people who don't know the equation you are talking about and tells nothing new to people who know it.

bawana 2y ago

The effect of stiffness can also be represented by stretchability of the string. Picking up a string with a free end will result in the same shape described by adding stiffness. A fanciful analogy might be a chain of springs with constant k2 where each spring junction is anchored to the ground with a spring with constant k1. If k2>>k1 the entire spring chain lifts in a gentle arc when a spring is lifted. If k1>>k2, only the springs near the pulling point really stretch and displace. It’s these kinds of simple analogies that engage our intuition. I still however cannot envision a mechanical analogy to demonstrate wavicles.

gweinberg 2y ago

One thing that confused me at the very beginning is, the author says the weak force is weak because it is short range. But the strong force is also short range.

lilyball 2y ago
The weak force is weak not because it has "short range" but because its range "dies off at distances ten million times smaller than an atom".
MathMonkeyMan 2y ago
The strong force is short range for a different reason. It's called [confinement][1]. The strong force gets stronger as you pull color charges apart. At some point the energy is so high that it's very likely that corresponding matching-color particles will exist, and so now there two pairs of close charges, instead of one pair of far charges. [1]: https://en.wikipedia.org/wiki/Color_confinement https://en.wikipedia.org/wiki/Color_confinement

JumpCrisscross 2y ago

> Google’s AI, for instance, and also here — that the virtual particles with mass actually “decay“ Do virtual particles decay?

vonneumannstan 2y ago

The real answer is we don't know or otherwise some kind of anthropic argument, i.e. the weak force has the range it does becuase otherwise we wouldn't have this kind of universe with people in it pondering why the weak force is the way it is. Seems generally unhelpful to say 'the weak force is short range because it's field is stiffer!' When you can then immediately say 'well why is the weak force's field stiffer?'

atoav 2y ago
Got you, but I am unsure if moving to the next question isn't a success as well. You understood a thing and move on, rinse and repeat. Or: consider where science would be had it operated under your proposed maxime for the past 3 centuries.
- vonneumannstan 2y ago
  Not sure I get this because we have no deeper understanding using the example I gave. I.e. The weak force is short range because it's field is stiffer -> the weak force's field is stiffer because it is more oblong -> the weak force's field is more oblong because it has more sparkles -> it has more sparkles because it ha slower mushiness -> it has more mushiness because ...etc. We haven't gained anything in that sequence. I don't think we can answer fundamental questions like this. The fine structure constant is the value it is because without that value we can't have a universe like this. Maybe in some multiverse system the physical laws and constants we know are fluid and can take different values in different universes but in our universe simply because of observation selection effects they can only be what they are.
  - atoav 2y ago
    Thw piano string produces a higer torque because it is shorter does not answer you why it is shorter or how waves travel exactly within it, but it sure as hell would be required knowledge to start researching beyond that first observation. > The weak force is short range because it's field is stiffer. May seem like a simple redirection that could go on forever, but we learned that fields can be stiffer, which probably wasn't all that clear. Now we can observe all other forces and look how their fields vary in terms of stiffness — a parameter we might not have thought about before. And by looking in those other places we might find a clue on how to shape an experiment that allows us to vary the stiffness. That could already have useful applications, but also lead to answering the question why some forces have stiffer fields than others.

dschleef 2y ago

This article goes to great contortions to avoid talking about electroweak theory or spontaneous symmetry breaking, both of which have decent Wikipedia articles, and are crucial to understanding what's going on here. Spontaneous symmetry breaking of the electroweak interaction and the Higgs mechanism is the reason _why_ the W and Z have mass. The article throws up a "who knows?" at this. When you write down the field equations for a massive boson field, you get an additional m^2 term in the denominator of the propagator, which contributes a e^(-r/m) term to the interaction force at low energy, such as the decay of a neutron or a weak-mediated nuclear decay. Is there an ELI5 version of this? I think the article tries, and it's always cool to see physics described from a different vantage point. My ELI5 version would be: fields with a massive gauge boson are "dragged down" in energy by the mass of the boson, so interactions propagate as if they have negative energy. What does a negative energy wave propagation look like? Similar negative energy wave propagations in physics are evanescent waves and electron tunneling, both of which have exponential drop-off terms, so it makes sense to see an exponential factor in massive boson interactions.

nyc111 2y ago

"In a quantum world such as ours, the field’s waves are made from indivisible tiny waves, which for historical reasons we call “particles.” Despite their name, these objects aren’t little dots; see Fig. 8." Does anyone know when physicists realized that the world is not made of indivisible units called "particles" but waves? Is there a specific experiment or are we talking about the results of many experiments?

T-A 2y ago
https://en.wikipedia.org/wiki/Wave%E2%80%93particle_duality https://en.wikipedia.org/wiki/Wave%E2%80%93particle_duality
- nyc111 2y ago
  But he is not talking about wave particle duality. He explicitly states that it is not helpful "to imagine them as both wave and particle." He calls waves with very small amplitude "particles" (for historical reasons). So, according to this picture the building blocks of the universe are waves. It makes no difference if physicists choose to call a wave "particle". Calling a wave particle does not make the wave a particle.
  - T-A 2y ago
    > He explicitly states that it is not helpful "to imagine them as both wave and particle." Where? I can't find that quote in the article. > He calls waves with very small amplitude "particles" (for historical reasons). The closest thing I see is In a quantum world such as ours, the field’s waves are made from indivisible tiny waves, which for historical reasons we call “particles.” Note the "indivisible" part. That's not how waves work in your everyday experience. The common understanding of "wave" is based on classical physics, where waves can be scaled up or down arbitrarily. But here you have "waves" which can only get so small, but no smaller, which he then goes on to parenthetically suggest calling "wavicles". Is coining a new word which is literally a combination of "wave" and "particle" not a way "to imagine them as both wave and particle"?

the__alchemist 2y ago

>NOTICE THERE IS NO QUANTUM PHYSICS IN THIS DISCUSSION! The short range of the field is a “classical” effect; i.e., it can be understood without any knowledge of the underlying role of quantum physics in our universe. It arises straightforwardly from ordinary field concepts and an ordinary differential equation. Nothing uncertain about it. It's interesting to me how fuzzy the definition of quantum physics is. For example, I've seen the description of particles as described by a wave function (e.g. electron position and momentum in an atom) labeled as a quantum phenomenon, but have also heard it, as in this quote, as classical, since it's defined by a differential equation; a "classical" wave. In that view, quantum only enters the model when modelling exchange effects, spin, fermion states etc. With the former definition, as in the article, you see descriptions of the wave nature of matter, replete with Planck's constant, complex wave function representations etc described as classical.

MagicMoonlight 2y ago

Stiffness just seems to be rewriting mass as a different term. Only things with mass have stiffness, stiffness is exactly proportional to mass, light isn’t stiff…

deleted 2y ago

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xyzzy9563 2y ago

The reason is because of the anthropic principle. If it wasn't short range, we probably wouldn't exist and there would be no consciousness to observe it.