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How the Higgs field gives mass to elementary particles

172 points by bigeatie 2y ago

russellbeattie 2y ago
> By suggesting that the Higgs field creates mass by exerting drag, they violate both Newton’s first and second laws of motion. Personally, I've wondered why theoretical physicists don't dive into Newton's laws more. Ever since I was a kid and first learned about the Voyager probes continuing to move through space forever, my question was why?? All matter is energy, and energy is vibrations in quantum fields, and that vibration never stops (you can never reach absolute zero). From the smallest gluon bouncing between quarks to galaxies to the expansion of the universe itself, matter never stops moving. Where does this infinite source of energy come from? I understand that physics simply describes how reality works, not why, but I think it'd be valuable to know the reason fields continue to vibrate forever.
TibbityFlanders 2y ago
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bloopernova 2y ago
Layman trying to wrap my head around this: the Higgs field causes other fields to stiffen by giving them a resonant frequency, with higher frequencies meaning more mass.
- fredgrott 2y ago
  keep in mind that its against the other whole mass of universe thing doing that same thing that also contributes to a mass reading.
- seiferteric 2y ago
  Hmm, now this is making me think, does the Higgs field act like an additional degree of freedom for energy to be dumped into? I mean like a photon is massless, so any amount of energy, it will already be going the speed of light so the only place where additional energy to go into is the frequency. Perhaps with massive particles, a portion of this additional energy now gets dumped into this resonant frequency rather than translating into motion? So the energy stored in this resonant frequency would be like the kinetic energy...? or maybe totally wrong :)
  - cryptonector 2y ago
    It's potential energy (m_0 c^2), but in a way it's also kinetic because it is a moving wave, it's just that it's a standing wave so it's as though it's reflecting, but being a standing wave causes that part of the particle's bundle of energy to manifest as potential energy.
deleted 2y ago
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wyager 2y ago
I studied wave mechanics in college, but the origin of mass didn't click for me until several years later (and in fact I don't believe it was every brought up in the context of wave mechanics, which seems like a problem in retrospect). The conceptualization that worked for me is this: The normal wave equation is (ignoring constant factors like mass and propagation velocity): d^2/dt^2 f(x,t) = d^2/dx^2 f(x,t) <acceleration> = <pulled towards neighbors> This says "if a point in the field is lower than its neighbors, it will be accelerated upwards. If a point in the field is higher than its neighbors, it will be accelerated downwards." This equation is the lowest-order description of most wave phenomena like sound waves, water surface waves, EM waves, etc. and it's usually pretty accurate. If you look for solutions to this differential equation, you can get f(x,t) = exp(i * w * (x±t)) w is the frequency of the wave This tells you that the frequency and wavenumber of waves is determined by the same parameter (w), so they are proportional to each other Now, what if we add a restoring force to this equation? This is a force that pulls the value of the field towards zero. d^2/dt^2 f(x,t) = d^2/dx^2 f(x,t) - M^2 f(x,t) M is just a parameter that tells you the strength of the restoring force. The force increases as the field gets farther from zero, like a spring. Now, solutions to the equation look instead like f(x,t) = exp(i*k*x ± i*w*t) Where w^2 = k^2 + M^2 (or something like that, I need to re-derive this on paper, just going off memory, but I think if you plug it in it should work) Notice that now, if you have a spacial frequency k, your temporal frequency is actually higher. In fact, if your spacial frequency k is 0 (corresponding to a stationary wave), your temporal frequency is still M! This is what mass is. Having a non-zero frequency even if the wave is the same everywhere in space (which corresponds to no movement) A field with no restoring force is e.g. the EM field, so photons are massless. The rate at which they oscillate in time is the same rate at which they oscillate in space. A massive particle has a restoring force, so its temporal frequency is higher than its spacial frequency. In physics, this equation is often reordered like this: d^2/dt^2 f(x,t) - d^2/dx^2 f(x,t) = - M^2 f(x,t) (d^2/dt^2 - d^2/dx^2) f(x,t) = - M^2 f(x,t) (d^2/dt^2 - d^2/dx^2) f(x,t) + M^2 f(x,t) = 0 ◻ f(x,t) + M^2 f(x,t) = 0 (the d'alembert operator) (◻ + M^2) f(x,t) = 0 Again, this is ignoring constant factors like c, h, etc. The above equation is nice because it's relativistically invariant. The d'alembert operator is the contraction of the 4-momentup operator with itself, p^u p_u. This is a concept worth studying - tells you a lot about what mass, energy, velocity, and momentum actually are in a general sense
tines 2y ago
So to conceptualize the difference between fields with and without restoring forces, I imagine that, for a field that doesn't have a restoring force, the medium itself can move permanently. For example if you have just a bunch of ball bearings lying on the surface of a table, you can cause a wave to go through the balls by hitting one. One bumps into the next, which bumps into the next, etc. There's no restoring force, so the wave is moving through the balls, and the balls are actually moving into a new position and they stay there. Compare that to a water wave, where gravity is trying to restore the particles to a "flat" position in space. If you cause a wave in water, the medium will return to the space it occupied before through the restoring force, even as the wave travels through it. Is this really how it works, so that e.g. the EM field itself can move in space, whereas e.g. the electron field cannot move in space, it's "pinned" in some sense by the Higgs field?
- wyager 2y ago
  First, worth noting that "the EM field" (the thing that shows up in the wave equation) in this case is specifically the EM 4-potential. This doesn't work if you try to treat "the EM field" as the strength of the E and B fields or something - it has to be the 4-potential. I got tripped up by this at one point Second, this isn't pinning the field in space, it's pinning the magnitude of the field to be close to some value (probably you can call that value 0) So if the field locally gets "too high" or "too low", there's a restoring force accelerating it back towards the "normal" value, like a spring attached to the normal value. It's not pinning it in the sense of stopping translation through space or time In the water wave analogy, we're using the vertical dimension to represent the magnitude of the water wave, but translating that to other contexts, we're not literally talking about a physical height, just the magnitude of the field. (Which, for all I know, maybe you can formulate that as a position in some higher-dimensional space or something)
  - tines 2y ago
    What trips me up is that we don't think of the field being a real physical thing. But isn't the field really the _true_ physical thing, and the wave is just a concept we overlay on it? Like, water is the real physical thing, and the wave is just an arrangement of the water that we recognize as humans. Isn't it the same with the EM and electron fields etc?
Angostura 2y ago
As a lay person, I found that a clear and understandable explanation, which in my experience suggests it is a wild wild over simplification - but enjoyable nonetheless A question for the more expert amongst you. Is the Higgs field unique in its interaction with other fields, or are there other similar fields which similarly change the way that other fields (and associated particles) behave?
- itishappy 2y ago
  I believe it's both. All fields can stiffen their fellows like this, but only the Higgs is stably non-zero.
  - thrtythreeforty 2y ago
    What's another example of cross-field interaction? Where (say) the EM field changes the restoring force of the gravitational field?
    - dataflow 2y ago
      Total layman here, but doesn't an EM field carry energy, and thus have similar effects as mass - thus warping spacetime?
    - itishappy 2y ago
      My mental model is that of the EM field coupling with the internal EM fields of a material to give rise to the phenomenon of index of refraction where light appears to move slower than the speed of light in a vacuum in said material. As I understand, a more advanced version of this occurs in superconductors which serves as a much better model of the phenomenon. At least I'm told it would if I could claim to understand it! https://physics.stackexchange.com/questions/33240/how-come-a-photon-acts-like-it-has-mass-in-a-superconducting-field https://physics.stackexchange.com/questions/33240/how-come-a... https://physics.stackexchange.com/questions/47791/what-do-massive-photons-have-to-do-with-superconductivity https://physics.stackexchange.com/questions/47791/what-do-ma...
- 2y ago
OgsyedIE 2y ago
How does this idea mesh with the other model given to laymen that the Higgs field causes charged particles to flip helicity extremely rapidly?
immibis 2y ago
And "the Higgs field suddenly switched on" is analogous to the pendulum's random vibrations slowing down enough that they no longer overwhelm its pendulum behaviour?
prof-dr-ir 2y ago
Very nice explanation by Matt Strassler. I am not sure it is possible to do better without getting into the details of quantum field theory. For those who know quantum mechanics I would add that the oscillations mentioned in the article are just the familiar exp( i E t ) of any wave function that is an eigenfunction of the Hamiltonian. For a particle at rest in a relativistic theory (and in units where c=1), we of course have E = m.
throw0101d 2y ago
> Quantum field theory, the powerful framework of modern particle physics, says the universe is filled with fields. Examples include the electromagnetic field, the gravitational field and the Higgs field itself. For each field, there’s a corresponding type of particle, best understood as a little ripple in that field. The electromagnetic field’s ripples are light waves, and its gentlest ripples are the particles of light, which we call photons. What are these fields made of? Are all fields made of the same thing(s), or is each field made differently?
- deleted 2y ago
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- layer8 2y ago
  They aren’t made of anything (other than numbers). Fields are currently the fundamental ontology. They are mathematical objects.
- cosignal 2y ago
  I think that’s a tricky question. In one sense, they aren’t made of anything since they are elementary fields. Meaning they don’t have constituent parts. But one could still argue that it’s relevant to say that they are of some kind of substance in a sense. The nature of that substance is the domain of Theories of Everything and some argue that the discussion becomes either purely mathematical or somewhat philosophical in nature, more so than a matter of physics anymore. For example, some argue that the fields are all made of math, so to speak, or likewise that their differences are like geometric variations on the same substrate.
- akomtu 2y ago
  Afaik, the official answer is that they are made of nothing because they are fundamental. That's how scientists say "we don't know". But when a fridge magnet sticks to a fridge, something holds it there and it's not nothing. It's not photons either. It's the magnetic field itself, the one that's made of "nothing". Photons are like waves in the magnetic field "water", but water isn't made of waves. Equations of magnetic field have a curious similarity with the flow of something in 4 dimensions (I mean that kaluza-klein theory), but nobody has managed to make that theory work yet, so there must be something else. Iirc, Einstein himself spent half of his life on this idea, but didn't succeed.
throw0101d 2y ago
> Once upon a time, there came into being a universe. Searingly hot, it swarmed with elementary particles. Among its fields was a Higgs field, initially switched off. But as the universe expanded and cooled, the Higgs field suddenly switched on, developing a nonzero strength. Any particular reason/mechanism why the Higgs field suddenly (gradually?) switched on?
- Sniffnoy 2y ago
  My understanding: The Higgs field, uniquely, has a nonzero vacuum expectation value -- so, when it's in its ground state, it's "switched on", it has an effect. In the early universe, it was in a higher energy state; for most fields, that would cause them to have an effect, but for the Higgs field that instead allowed it to take on a zero vacuum expectation value and to be "switched off". The Higgs takes on nonzero values at low energies instead of at high energies like other fields, so it "switched on" as the universe cooled.
  - antihipocrat 2y ago
    Is it possible for there to be other undiscovered fields with a similar mechanic - turning on when the universe hits a future heat threshold?
    - elashri 2y ago
      What you are trying to describe is what we call phase transition. So just to make it clear the reason higgs field working like that is that after the big bang and cooling of universe to about 10^5 kelvins (don't try to convert this to this strange unit of Fahrenheit) the field transitioned from high energy state to lower energy state. This is what gave rise to the higgs mechanism (what the article talks about). Now this mechanism is responsible for the electroweak symmetry breaking, could it be others? Yes many think so. A lot of grand unification theories (GUTs) predict existence of some. The most famous one is Supersymmetry. There is a term called GUT phase transition that describes these fields. Well another particular similar field would be what cosmology people call the inflaton. It is hypothesized that it has driven the expansion of the universe during the inflation event. But that cannot be repeated because it needs much higher energy state that it cannot be happening again. But some theories of dark matter involve fields that could still be in a symmetric state (like higgs before phase transition) and that these fields would undergo a phase transition that we can see some observation like changes in dark matter distribution. There is the concept of late dark matter symmetry and false vaccum decay (an idea that we are actually in a local minimum and that the true absolute point is not reached yet. If this is true it would be interested as if we reached this point then laws of physics will change (not our understanding but literally the laws will change). This could lead to a changes in particles properties, masses and forces. This could even change the structure of the space-time itself. This transition will be interesting because it could propagate as a bubble through the universe at speed of light. It seems more on a verge of science fiction but there is a theory behind that [1] [1] https://en.m.wikipedia.org/wiki/False_vacuum https://en.m.wikipedia.org/wiki/False_vacuum
idontwantthis 2y ago
Does anyone know the genesis of the Higg’s field as mud explanation? I remember reading that since I first heard about the “God Particle” in the Science Times maybe 20 years ago. Have journalists been using that deeply flawed analogy since Higg’s hypothesis was first published?
hinkley 2y ago
Imagine some preindustrial scientist being awakened in the modern era to find that the aether has been first debunked for more than a century and then rediscovered, but with different rules.
- emrah 2y ago
  Aether has a specific definition and it still does not exist. It was not rediscovered. QFT is not aether-like. Aether was a substance filling all space, while QFT fields like higgs are not physical at all (but rather give rise to physical properties)
  - calf 2y ago
    How does something not physical give rise to physical properties? Saying that way makes it sounds like a logical conceit is being used.
    - TheOtherHobbes 2y ago
      It organises stuff instead of being stuff. Which is less of a logical conceit, and more metaphysics. No one knows what quantum fields are made of. There are various ideas (loop quantum gravity, causal dynamical triangulation, others...) but QFT defines what quantum fields do, not what their component parts are at a more fundamental level.
  - wyager 2y ago
    > QFT fields like higgs are not physical at all (but rather give rise to physical properties) I think this is a nonsense cop-out and bad ontology. What does it mean to "be physical" if not to be causally downstream of other physical effects?
  - Maxatar 2y ago
    What was the "specific" definition of the aether? It looks from reviewing the history that there was no consensus on what the aether was or what its properties were. Interestingly enough what I did manage to find is a lecture given by Einstein in 1920 where he argues that the ether is in fact essential towards the understanding of general relativity, and that it could be through the ether that gravity and electromagnetism are unified: https://www.researchgate.net/publication/358617464_Ether_and_the_Theory_of_Relativity https://www.researchgate.net/publication/358617464_Ether_and...
mfworks 2y ago
PBS Spacetime has a fantastic video on the Higgs Field that explains it about one level deeper that typical pop science, and answers some of the questions I'm seeing in this thread, include "why did the field switch on suddenly?" and "Why is the Higgs Field different from other fields" link: https://www.youtube.com/watch?v=G0Q4UAiKacw https://www.youtube.com/watch?v=G0Q4UAiKacw
- programd 2y ago
  I can also add this set of articles from Matt Strassler which explains it all with surprisingly simple math. It really is quite understandable and I wish more pop-sci discussions of the subject threw in a few equations now and then to explain such stuff. https://profmattstrassler.com/articles-and-posts/particle-physics-basics/how-the-higgs-field-works-with-math/ https://profmattstrassler.com/articles-and-posts/particle-ph...
  - TexanFeller 2y ago
    Sean Carroll produces a great deal of content for people that want a bit more rigorous explanation rather than the leaky metaphors of most popsci. He often delves into equations and technical details, but keeps it at a level mostly understandable for someone who has basic scientific understanding, but isn't a professional/academic. I spend many hours every month listening to him and recommend his content every chance I get.
    - pantulis 2y ago
      Carroll's latest book "Quanta and Fields: The Biggest Ideas in the Universe" is about all this quantum field theory, and I think it perfectly covers the gap between pop-sci and academic material for people with some math exposure. While other authors just keep shy of equations and thus need to resort to simplified analogies, Carroll is not afraid of throwing a good share of math stuff and explaining the rationale from one equation to the other, while avoiding the really hard parts ("solving this equation tortures undergrad physics students for a year, but we won't be doing that")
sieste 2y ago
> A common approach has been to tell a tall tale. Here’s one version: There’s this substance, like a soup, that fills the universe; that’s the Higgs field. As particles move through it, the soup slows them down, and that’s how particles get mass. Is that really so? I've never heard this analogy, so the whole premise seems a bit of a straw man...
- Sniffnoy 2y ago
  I've seen it a bunch, FWIW.
- pests 2y ago
  A "tall tale" is one that is likely false.
- pdonis 2y ago
  > Is that really so? As the article notes, no, this is not a correct description.
  - sieste 2y ago
    sorry for the confusion, I meant is it really the case that this is a commonly used description of the higgs field.
    - pdonis 2y ago
      > is it really the case that this is a commonly used description of the higgs field. For whatever it's worth, it's not a description I had seen before I read the article. It's certainly not one you're going to find in actual textbooks or physics papers.
tsimionescu 2y ago
If anyone wants to dig deeper, there is an excellent lecture on YouTube by Leonard Susskind. This goes into some details on how fields in general give mass to (composite) particles, and how the Higgs field has certain properties that allow it to give mass to elementary particles. It goes only into a tiny bit of math, absolutely intelligible at the high-school or at least undergraduate level. https://youtube.com/watch?v=JqNg819PiZY https://youtube.com/watch?v=JqNg819PiZY
simpaticoder 2y ago
This article is suspect as it mentions a "stationary electron". Such an electron would have precisely known momentum, and so exist throughout all of spacetime. This is a common starting point for solving the (e.g. Dirac) equations, but it's not physical.

172 points by bigeatie 2y ago

> By suggesting that the Higgs field creates mass by exerting drag, they violate both Newton’s first and second laws of motion. Personally, I've wondered why theoretical physicists don't dive into Newton's laws more. Ever since I was a kid and first learned about the Voyager probes continuing to move through space forever, my question was why?? All matter is energy, and energy is vibrations in quantum fields, and that vibration never stops (you can never reach absolute zero). From the smallest gluon bouncing between quarks to galaxies to the expansion of the universe itself, matter never stops moving. Where does this infinite source of energy come from? I understand that physics simply describes how reality works, not why, but I think it'd be valuable to know the reason fields continue to vibrate forever.

TibbityFlanders 2y ago

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bloopernova 2y ago

Layman trying to wrap my head around this: the Higgs field causes other fields to stiffen by giving them a resonant frequency, with higher frequencies meaning more mass.

fredgrott 2y ago
keep in mind that its against the other whole mass of universe thing doing that same thing that also contributes to a mass reading.
seiferteric 2y ago
Hmm, now this is making me think, does the Higgs field act like an additional degree of freedom for energy to be dumped into? I mean like a photon is massless, so any amount of energy, it will already be going the speed of light so the only place where additional energy to go into is the frequency. Perhaps with massive particles, a portion of this additional energy now gets dumped into this resonant frequency rather than translating into motion? So the energy stored in this resonant frequency would be like the kinetic energy...? or maybe totally wrong :)
- cryptonector 2y ago
  It's potential energy (m_0 c^2), but in a way it's also kinetic because it is a moving wave, it's just that it's a standing wave so it's as though it's reflecting, but being a standing wave causes that part of the particle's bundle of energy to manifest as potential energy.

deleted 2y ago

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wyager 2y ago

I studied wave mechanics in college, but the origin of mass didn't click for me until several years later (and in fact I don't believe it was every brought up in the context of wave mechanics, which seems like a problem in retrospect). The conceptualization that worked for me is this: The normal wave equation is (ignoring constant factors like mass and propagation velocity): d^2/dt^2 f(x,t) = d^2/dx^2 f(x,t) <acceleration> = <pulled towards neighbors> This says "if a point in the field is lower than its neighbors, it will be accelerated upwards. If a point in the field is higher than its neighbors, it will be accelerated downwards." This equation is the lowest-order description of most wave phenomena like sound waves, water surface waves, EM waves, etc. and it's usually pretty accurate. If you look for solutions to this differential equation, you can get f(x,t) = exp(i * w * (x±t)) w is the frequency of the wave This tells you that the frequency and wavenumber of waves is determined by the same parameter (w), so they are proportional to each other Now, what if we add a restoring force to this equation? This is a force that pulls the value of the field towards zero. d^2/dt^2 f(x,t) = d^2/dx^2 f(x,t) - M^2 f(x,t) M is just a parameter that tells you the strength of the restoring force. The force increases as the field gets farther from zero, like a spring. Now, solutions to the equation look instead like f(x,t) = exp(i*k*x ± i*w*t) Where w^2 = k^2 + M^2 (or something like that, I need to re-derive this on paper, just going off memory, but I think if you plug it in it should work) Notice that now, if you have a spacial frequency k, your temporal frequency is actually higher. In fact, if your spacial frequency k is 0 (corresponding to a stationary wave), your temporal frequency is still M! This is what mass is. Having a non-zero frequency even if the wave is the same everywhere in space (which corresponds to no movement) A field with no restoring force is e.g. the EM field, so photons are massless. The rate at which they oscillate in time is the same rate at which they oscillate in space. A massive particle has a restoring force, so its temporal frequency is higher than its spacial frequency. In physics, this equation is often reordered like this: d^2/dt^2 f(x,t) - d^2/dx^2 f(x,t) = - M^2 f(x,t) (d^2/dt^2 - d^2/dx^2) f(x,t) = - M^2 f(x,t) (d^2/dt^2 - d^2/dx^2) f(x,t) + M^2 f(x,t) = 0 ◻ f(x,t) + M^2 f(x,t) = 0 (the d'alembert operator) (◻ + M^2) f(x,t) = 0 Again, this is ignoring constant factors like c, h, etc. The above equation is nice because it's relativistically invariant. The d'alembert operator is the contraction of the 4-momentup operator with itself, p^u p_u. This is a concept worth studying - tells you a lot about what mass, energy, velocity, and momentum actually are in a general sense

tines 2y ago

So to conceptualize the difference between fields with and without restoring forces, I imagine that, for a field that doesn't have a restoring force, the medium itself can move permanently. For example if you have just a bunch of ball bearings lying on the surface of a table, you can cause a wave to go through the balls by hitting one. One bumps into the next, which bumps into the next, etc. There's no restoring force, so the wave is moving through the balls, and the balls are actually moving into a new position and they stay there. Compare that to a water wave, where gravity is trying to restore the particles to a "flat" position in space. If you cause a wave in water, the medium will return to the space it occupied before through the restoring force, even as the wave travels through it. Is this really how it works, so that e.g. the EM field itself can move in space, whereas e.g. the electron field cannot move in space, it's "pinned" in some sense by the Higgs field?

wyager 2y ago
First, worth noting that "the EM field" (the thing that shows up in the wave equation) in this case is specifically the EM 4-potential. This doesn't work if you try to treat "the EM field" as the strength of the E and B fields or something - it has to be the 4-potential. I got tripped up by this at one point Second, this isn't pinning the field in space, it's pinning the magnitude of the field to be close to some value (probably you can call that value 0) So if the field locally gets "too high" or "too low", there's a restoring force accelerating it back towards the "normal" value, like a spring attached to the normal value. It's not pinning it in the sense of stopping translation through space or time In the water wave analogy, we're using the vertical dimension to represent the magnitude of the water wave, but translating that to other contexts, we're not literally talking about a physical height, just the magnitude of the field. (Which, for all I know, maybe you can formulate that as a position in some higher-dimensional space or something)
- tines 2y ago
  What trips me up is that we don't think of the field being a real physical thing. But isn't the field really the _true_ physical thing, and the wave is just a concept we overlay on it? Like, water is the real physical thing, and the wave is just an arrangement of the water that we recognize as humans. Isn't it the same with the EM and electron fields etc?

Angostura 2y ago

As a lay person, I found that a clear and understandable explanation, which in my experience suggests it is a wild wild over simplification - but enjoyable nonetheless A question for the more expert amongst you. Is the Higgs field unique in its interaction with other fields, or are there other similar fields which similarly change the way that other fields (and associated particles) behave?

itishappy 2y ago
I believe it's both. All fields can stiffen their fellows like this, but only the Higgs is stably non-zero.
- thrtythreeforty 2y ago
  What's another example of cross-field interaction? Where (say) the EM field changes the restoring force of the gravitational field?
  - dataflow 2y ago
    Total layman here, but doesn't an EM field carry energy, and thus have similar effects as mass - thus warping spacetime?
  - itishappy 2y ago
    My mental model is that of the EM field coupling with the internal EM fields of a material to give rise to the phenomenon of index of refraction where light appears to move slower than the speed of light in a vacuum in said material. As I understand, a more advanced version of this occurs in superconductors which serves as a much better model of the phenomenon. At least I'm told it would if I could claim to understand it! https://physics.stackexchange.com/questions/33240/how-come-a-photon-acts-like-it-has-mass-in-a-superconducting-field https://physics.stackexchange.com/questions/33240/how-come-a... https://physics.stackexchange.com/questions/47791/what-do-massive-photons-have-to-do-with-superconductivity https://physics.stackexchange.com/questions/47791/what-do-ma...
2y ago

OgsyedIE 2y ago

How does this idea mesh with the other model given to laymen that the Higgs field causes charged particles to flip helicity extremely rapidly?

immibis 2y ago

And "the Higgs field suddenly switched on" is analogous to the pendulum's random vibrations slowing down enough that they no longer overwhelm its pendulum behaviour?

prof-dr-ir 2y ago

Very nice explanation by Matt Strassler. I am not sure it is possible to do better without getting into the details of quantum field theory. For those who know quantum mechanics I would add that the oscillations mentioned in the article are just the familiar exp( i E t ) of any wave function that is an eigenfunction of the Hamiltonian. For a particle at rest in a relativistic theory (and in units where c=1), we of course have E = m.

throw0101d 2y ago

> Quantum field theory, the powerful framework of modern particle physics, says the universe is filled with fields. Examples include the electromagnetic field, the gravitational field and the Higgs field itself. For each field, there’s a corresponding type of particle, best understood as a little ripple in that field. The electromagnetic field’s ripples are light waves, and its gentlest ripples are the particles of light, which we call photons. What are these fields made of? Are all fields made of the same thing(s), or is each field made differently?

deleted 2y ago
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layer8 2y ago
They aren’t made of anything (other than numbers). Fields are currently the fundamental ontology. They are mathematical objects.
cosignal 2y ago
I think that’s a tricky question. In one sense, they aren’t made of anything since they are elementary fields. Meaning they don’t have constituent parts. But one could still argue that it’s relevant to say that they are of some kind of substance in a sense. The nature of that substance is the domain of Theories of Everything and some argue that the discussion becomes either purely mathematical or somewhat philosophical in nature, more so than a matter of physics anymore. For example, some argue that the fields are all made of math, so to speak, or likewise that their differences are like geometric variations on the same substrate.
akomtu 2y ago
Afaik, the official answer is that they are made of nothing because they are fundamental. That's how scientists say "we don't know". But when a fridge magnet sticks to a fridge, something holds it there and it's not nothing. It's not photons either. It's the magnetic field itself, the one that's made of "nothing". Photons are like waves in the magnetic field "water", but water isn't made of waves. Equations of magnetic field have a curious similarity with the flow of something in 4 dimensions (I mean that kaluza-klein theory), but nobody has managed to make that theory work yet, so there must be something else. Iirc, Einstein himself spent half of his life on this idea, but didn't succeed.

throw0101d 2y ago

> Once upon a time, there came into being a universe. Searingly hot, it swarmed with elementary particles. Among its fields was a Higgs field, initially switched off. But as the universe expanded and cooled, the Higgs field suddenly switched on, developing a nonzero strength. Any particular reason/mechanism why the Higgs field suddenly (gradually?) switched on?

Sniffnoy 2y ago
My understanding: The Higgs field, uniquely, has a nonzero vacuum expectation value -- so, when it's in its ground state, it's "switched on", it has an effect. In the early universe, it was in a higher energy state; for most fields, that would cause them to have an effect, but for the Higgs field that instead allowed it to take on a zero vacuum expectation value and to be "switched off". The Higgs takes on nonzero values at low energies instead of at high energies like other fields, so it "switched on" as the universe cooled.
- antihipocrat 2y ago
  Is it possible for there to be other undiscovered fields with a similar mechanic - turning on when the universe hits a future heat threshold?
  - elashri 2y ago
    What you are trying to describe is what we call phase transition. So just to make it clear the reason higgs field working like that is that after the big bang and cooling of universe to about 10^5 kelvins (don't try to convert this to this strange unit of Fahrenheit) the field transitioned from high energy state to lower energy state. This is what gave rise to the higgs mechanism (what the article talks about). Now this mechanism is responsible for the electroweak symmetry breaking, could it be others? Yes many think so. A lot of grand unification theories (GUTs) predict existence of some. The most famous one is Supersymmetry. There is a term called GUT phase transition that describes these fields. Well another particular similar field would be what cosmology people call the inflaton. It is hypothesized that it has driven the expansion of the universe during the inflation event. But that cannot be repeated because it needs much higher energy state that it cannot be happening again. But some theories of dark matter involve fields that could still be in a symmetric state (like higgs before phase transition) and that these fields would undergo a phase transition that we can see some observation like changes in dark matter distribution. There is the concept of late dark matter symmetry and false vaccum decay (an idea that we are actually in a local minimum and that the true absolute point is not reached yet. If this is true it would be interested as if we reached this point then laws of physics will change (not our understanding but literally the laws will change). This could lead to a changes in particles properties, masses and forces. This could even change the structure of the space-time itself. This transition will be interesting because it could propagate as a bubble through the universe at speed of light. It seems more on a verge of science fiction but there is a theory behind that [1] [1] https://en.m.wikipedia.org/wiki/False_vacuum https://en.m.wikipedia.org/wiki/False_vacuum

idontwantthis 2y ago

Does anyone know the genesis of the Higg’s field as mud explanation? I remember reading that since I first heard about the “God Particle” in the Science Times maybe 20 years ago. Have journalists been using that deeply flawed analogy since Higg’s hypothesis was first published?

hinkley 2y ago

Imagine some preindustrial scientist being awakened in the modern era to find that the aether has been first debunked for more than a century and then rediscovered, but with different rules.

emrah 2y ago
Aether has a specific definition and it still does not exist. It was not rediscovered. QFT is not aether-like. Aether was a substance filling all space, while QFT fields like higgs are not physical at all (but rather give rise to physical properties)
- calf 2y ago
  How does something not physical give rise to physical properties? Saying that way makes it sounds like a logical conceit is being used.
  - TheOtherHobbes 2y ago
    It organises stuff instead of being stuff. Which is less of a logical conceit, and more metaphysics. No one knows what quantum fields are made of. There are various ideas (loop quantum gravity, causal dynamical triangulation, others...) but QFT defines what quantum fields do, not what their component parts are at a more fundamental level.
- wyager 2y ago
  > QFT fields like higgs are not physical at all (but rather give rise to physical properties) I think this is a nonsense cop-out and bad ontology. What does it mean to "be physical" if not to be causally downstream of other physical effects?
- Maxatar 2y ago
  What was the "specific" definition of the aether? It looks from reviewing the history that there was no consensus on what the aether was or what its properties were. Interestingly enough what I did manage to find is a lecture given by Einstein in 1920 where he argues that the ether is in fact essential towards the understanding of general relativity, and that it could be through the ether that gravity and electromagnetism are unified: https://www.researchgate.net/publication/358617464_Ether_and_the_Theory_of_Relativity https://www.researchgate.net/publication/358617464_Ether_and...

mfworks 2y ago

PBS Spacetime has a fantastic video on the Higgs Field that explains it about one level deeper that typical pop science, and answers some of the questions I'm seeing in this thread, include "why did the field switch on suddenly?" and "Why is the Higgs Field different from other fields" link: https://www.youtube.com/watch?v=G0Q4UAiKacw https://www.youtube.com/watch?v=G0Q4UAiKacw

programd 2y ago
I can also add this set of articles from Matt Strassler which explains it all with surprisingly simple math. It really is quite understandable and I wish more pop-sci discussions of the subject threw in a few equations now and then to explain such stuff. https://profmattstrassler.com/articles-and-posts/particle-physics-basics/how-the-higgs-field-works-with-math/ https://profmattstrassler.com/articles-and-posts/particle-ph...
- TexanFeller 2y ago
  Sean Carroll produces a great deal of content for people that want a bit more rigorous explanation rather than the leaky metaphors of most popsci. He often delves into equations and technical details, but keeps it at a level mostly understandable for someone who has basic scientific understanding, but isn't a professional/academic. I spend many hours every month listening to him and recommend his content every chance I get.
  - pantulis 2y ago
    Carroll's latest book "Quanta and Fields: The Biggest Ideas in the Universe" is about all this quantum field theory, and I think it perfectly covers the gap between pop-sci and academic material for people with some math exposure. While other authors just keep shy of equations and thus need to resort to simplified analogies, Carroll is not afraid of throwing a good share of math stuff and explaining the rationale from one equation to the other, while avoiding the really hard parts ("solving this equation tortures undergrad physics students for a year, but we won't be doing that")

sieste 2y ago

> A common approach has been to tell a tall tale. Here’s one version: There’s this substance, like a soup, that fills the universe; that’s the Higgs field. As particles move through it, the soup slows them down, and that’s how particles get mass. Is that really so? I've never heard this analogy, so the whole premise seems a bit of a straw man...

Sniffnoy 2y ago
I've seen it a bunch, FWIW.
pests 2y ago
A "tall tale" is one that is likely false.
pdonis 2y ago
> Is that really so? As the article notes, no, this is not a correct description.
- sieste 2y ago
  sorry for the confusion, I meant is it really the case that this is a commonly used description of the higgs field.
  - pdonis 2y ago
    > is it really the case that this is a commonly used description of the higgs field. For whatever it's worth, it's not a description I had seen before I read the article. It's certainly not one you're going to find in actual textbooks or physics papers.

tsimionescu 2y ago

If anyone wants to dig deeper, there is an excellent lecture on YouTube by Leonard Susskind. This goes into some details on how fields in general give mass to (composite) particles, and how the Higgs field has certain properties that allow it to give mass to elementary particles. It goes only into a tiny bit of math, absolutely intelligible at the high-school or at least undergraduate level. https://youtube.com/watch?v=JqNg819PiZY https://youtube.com/watch?v=JqNg819PiZY

simpaticoder 2y ago

This article is suspect as it mentions a "stationary electron". Such an electron would have precisely known momentum, and so exist throughout all of spacetime. This is a common starting point for solving the (e.g. Dirac) equations, but it's not physical.