[HN Gopher] How the Higgs field gives mass to elementary particles
___________________________________________________________________
How the Higgs field gives mass to elementary particles
Author : bigeatie
Score : 133 points
Date : 2024-09-03 16:11 UTC (6 hours ago)
(HTM) web link (www.quantamagazine.org)
(TXT) w3m dump (www.quantamagazine.org)
| bloopernova wrote:
| 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 wrote:
| 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 wrote:
| 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 wrote:
| 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.
| wyager wrote:
| 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 wrote:
| > The rate at which they oscillate in time is the same rate at
| which they oscillate in space.
|
| Wouldn't it be the opposite, that they do not oscillate in time
| at all so that they oscillate in space as rapidly as possible
| (since, as we know, time doesn't pass for photons)? And
| stationary particles don't oscillate in space, so they
| oscillate in time as rapidly as possible. Or are you using
| "oscillate" in a different sense here?
| wyager wrote:
| Photons have their spacial frequency directly locked to their
| temporal frequency.
|
| Temporal frequency f
|
| Spacial frequency k
|
| f = k * c
|
| Dimensional analysis: t^-1 = l^-1 * l t^-1
| oytuntez wrote:
| chatgpt convo to understand "temporal frequency" better:
| https://chatgpt.com/share/f8601523-2d3f-4497-a9b4-071d6a8778...
| cryptonector wrote:
| This is beautiful. Thanks for this. Is the choice of `M` for
| "the strength of the restoring force" intended to resemble `m`
| for mass?
| tines wrote:
| 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 wrote:
| 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 wrote:
| 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?
| layer8 wrote:
| For fields, it's rather that the wave is the only
| physical/real thing, and there is no separate "substance"
| that is waving. "Substance" is a concept that disappears in
| fundamental physics.
| wyager wrote:
| At some point this all kind of drifts apart from ontic
| science and starts to become a matter of narrative or
| interpretation, but I would generally agree with that.
|
| Waves are mathematically-friendly possible configurations
| of the underlying system.
|
| It's mathematically valid to choose the most convenient
| configurations for analysis because the systems are
| (pretty) linear, so we can just project any actual state
| into a sum of wave states, apply our mathematical model,
| and add it all back to get the new real state.
|
| A lot of physical phenomena are composed of pretty
| predictable distributions of wave states, so projecting
| from a realistic state to a sum of wave states is usually
| straightforward enough.
|
| For example, a moving particle looks like the sum of a
| bunch of waves all closely grouped around a particular
| wavelength.
| cryptonector wrote:
| Think of a field as a set of scalar field strength values,
| one value at every point in space. It's not a "thing" you
| can grab or see. The field strength values are based on the
| distances to and the magnitudes of the "particles" have
| have {charge, mass, color, whatever} (with the complexity
| that the particles themselves are really just standing
| waves, thus the scare quotes).
| Angostura wrote:
| 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 wrote:
| I believe it's both. All fields can stiffen their fellows like
| this, but only the Higgs is stably non-zero.
| thrtythreeforty wrote:
| What's another example of cross-field interaction? Where
| (say) the EM field changes the restoring force of the
| gravitational field?
| dataflow wrote:
| Total layman here, but doesn't an EM field carry energy,
| and thus have similar effects as mass - thus warping
| spacetime?
| itishappy wrote:
| 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...
|
| https://physics.stackexchange.com/questions/47791/what-do-
| ma...
| emblaegh wrote:
| I'm not a qft-ist, but from the top my head the Higgs field
| wouldn't explain the (likely positive) mass of neutrinos. So
| there could potentially be another mass creation mechanism. But
| someone else more informed could clarify.
| eigenket wrote:
| There are essentially two "easy" ways to add neutrino mass to
| the standard model without breaking things too much.
|
| One is to use the Higgs to give neutrinos mass. For technical
| reasons this only works if there are both right and left
| handed neutrinos. We have only ever detected left handed
| neutrinos, so you'd have to also add right handed neutrinos,
| and just say that they don't really interact with anything
| else.
|
| The second way you can do it is add a very heavy Majorana
| particle to your theory for each of the 3 neutrinos we know
| about. These Majorana particles are their own anti-particle
| (just like the photon is) and as a result are able to have a
| non-zero mass without the Higg's mechanism. The three types
| of neutrinos we already know about would then get their
| masses as a result of some slightly complicated maths
| involving the masses of the three new Majorana neutrinos.
| OgsyedIE wrote:
| 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 wrote:
| 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 wrote:
| 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 wrote:
| > _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?
| layer8 wrote:
| They aren't made of anything (other than numbers). Fields are
| currently the fundamental ontology. They are mathematical
| objects.
| cosignal wrote:
| 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 wrote:
| 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.
| jmcclell wrote:
| The book Waves in an Impossible Sea really goes into some depth
| on this (for a layman -- which I am) and tries to drive home
| the point that there are two perspectives one might take.
| There's the perspective of the medium and the perspective of
| the field.
|
| Using wind, as an example, we can measure the wind
| speed/direction at various points in a given space. We don't
| need to know what wind _is_ to feel its effects. Instead, we
| might view it as a force wave that propagates through space and
| interacts with everyday objects. The measurements of this force
| that we take at various points in space across a given area
| form what we might call the Wind Field. We don 't need to know
| the nature of the medium these wind waves propagate through in
| order to study wind and how it interacts with other objects.
| This is the field perspective.
|
| Of course, we know that wind is _really_ an effect of air
| molecules moving through space. That is, the medium for wind is
| the atmosphere. This gives us deeper insight into what wind is
| and how it works. This is the medium perspective.
|
| According to the book, we don't know what the media for the
| elementary particles are or if there even are any. Our
| intuition based on waves that we see in everyday life tell us
| that there must be some medium through which the wave can
| propagate, but thus far we have found no such medium for waves
| such as light.
|
| We just know there are measurable properties that we can
| measure across points in space and we have created mathematical
| objects (fields) to represent this. From there, we can
| construct theories and make predictions based on these models.
| oezi wrote:
| I always thought the fields are just the mathematical
| representation of the respective force carrier particles
| travelling through space. Such particles (the photon is
| certainly the most relevant for us) are having such a big size
| due to their statistical nature that the fill space even though
| their own size when probed is tiny.
| halyconWays wrote:
| Particles don't actually exist, however. They're excitations
| in various fields. A proton, for example, is actually a sea
| of three quarks of different "colors" that continually
| exchange energy (and only have potential positions) via
| gluons, and those quarks and gluons themselves aren't
| particles, but excitations in fields
| oezi wrote:
| So we have a duality of fields and particles. Likely it
| doesn't make sense to give one representation precedence
| over the other.
| calf wrote:
| Yeah did everything forget about the double slit
| experiment? Why are fields any more real than particles?
| Is the updated science now resolved on wave particle
| duality then?
| halyconWays wrote:
| It's more like, particles are how we experience collapsed
| wave functions, and both are manifestations of
| excitations in the underlying quantum field.
| halyconWays wrote:
| QFT doesn't have a duality of particles and waves, it
| explains both as excitations in underlying fields. So
| even the particle in a double slit experiment is just the
| collapsed wave function, but we experience it as a
| particle. So precedence in this case is that QFT is the
| underlying explanation.
| cryptonector wrote:
| Fields aren't made of anything. When you feel static
| electricity, like when you rub a balloon against your hair, and
| your hair then stands up, that electric charge on the balloon
| and your hair is somehow being made evident across the space
| between the hair and the balloon. That communication of force
| electric charge happens over the electric (really,
| electromagnetic) field. It happens across air and vacuum alike.
| Nothing need be between the charged objects and yet the charge
| will be "felt" by them. That "field" is just the numeric
| electric charge felt at each point in space, for all points in
| space. It's just field _strength_ -- a bunch of scalar values,
| one for every point in in space. We call that a field, but it
| 's not an object made of stuff, just a mathematical object.
| throw0101d wrote:
| > _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?
| LegitShady wrote:
| If the higgs field did not exist, particles would not have
| enough mass to attract each other, and the universe as we know
| it would not exist.
|
| So while I do not know if there is some particular cause of the
| higgs field, no reality like ours would exist without it, and
| realities without it would not look like anything we recognize
| (although maybe scientists could simulate it).
| emblaegh wrote:
| Beware when mixing quantum field theory (Higgs) with gravity
| (attraction). We don't have any idea how these two relate to
| each other.
| LegitShady wrote:
| the entire theory of the higgs field and its discovery came
| from understanding that the model without it lacked
| sufficient gravity to match the world around us.
|
| So I understand what you're saying, I disagree that we
| don't know how these to relate to each other. The reason
| Peter Higgs theorized the higgs field is because we have
| some idea of it.Maybe it gets more complicated than we
| understand currently, but we understood it enough to guess
| some properties of the higgs boson and discover it
| experimentally.
| pdonis wrote:
| _> the entire theory of the higgs field and its discovery
| came from understanding that the model without it lacked
| sufficient gravity to match the world around us._
|
| No, it didn't. Mass is not required for gravity; only
| energy is. The energy was there before the electroweak
| phase transition; it just wasn't in the form of rest
| mass. It still produced gravity.
| LegitShady wrote:
| The end of the electroweak epoch is estimated at 10^-12
| seconds after the big bang. So while I understand that
| something existed prior to the universe as we understand
| it now, for the overwhelming majority of the existence of
| reality we have lived in a reality after the electroweak
| phase transition, and the universe we live in today and
| the features we recognize of it are a result of forces
| including the effect of the higgs field on mass and thus
| gravity.
|
| So you're right technically, but it has nothing to do
| with what I said in my first comment - without the higgs
| field the universe as we know it today would be
| unrecognizable, and a universe without a higgs field
| would not look like ours.
| leptons wrote:
| >Mass is not required for gravity; only energy is.
|
| E = MC^2
|
| Can't have energy without mass, and mass leads to
| gravity.
| pdonis wrote:
| _> If the higgs field did not exist, particles would not have
| enough mass to attract each other, and the universe as we
| know it would not exist._
|
| This is not correct. Rest mass is not required for gravity.
| The source of gravity in GR is the stress-energy tensor,
| which was nonzero in the early universe even though all of
| the Standard Model fields were massless. Indeed, a vacuum
| electromagnetic field today has a nonzero stress-energy
| tensor even though, at the QFT level, it is a massless field
| (the photon).
| svachalek wrote:
| It is believed to be the cooling of the universe. At
| ridiculously high temperatures, such that have not existed
| since the first fraction of a second of the universe, the
| electroweak symmetry was broken and most physics we are
| familiar with didn't work. Unfortunately the math behind it is
| way over my head so that's about all I can say on it.
| benreesman wrote:
| Not a physicist, just a fan. As far as I understand it, we
| believe that it was in the early universe that the symmetry
| was unbroken [1].
|
| [1] https://en.wikipedia.org/wiki/Electroweak_interaction#Aft
| er_...
| pdonis wrote:
| _> Any particular reason /mechanism why the Higgs field
| suddenly (gradually?) switched on?_
|
| "Switched on" is not really a good description. According to my
| understanding of our best current model, the Higgs field was
| _not_ in its vacuum state in the very early universe--there
| were lots of Higgs particles around--so it was not "switched
| off" any more than any of the other Standard Model fields were.
| But in the very early universe, the electroweak interaction
| worked differently than it does now. As the universe cooled,
| there was a phase transition that changed how the electroweak
| interaction worked, and after that phase transition, the Higgs
| field acquired what is called a nonzero "vacuum expectation
| value", meaning that even though there were no longer any Higgs
| particles around-- the Higgs field was in its vacuum state--
| that vacuum state now corresponded to a nonzero value of the
| Higgs field, meaning that the field can interact with other
| fields, and that interaction is what we observe as mass for
| those other fields.
| Sniffnoy wrote:
| 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 wrote:
| Is it possible for there to be other undiscovered fields with
| a similar mechanic - turning on when the universe hits a
| future heat threshold?
| pb1729 wrote:
| tldr is that it happened because the universe cooled down from
| a stupendously insanely high temperature to a merely insanely
| high temperature shortly after the big bang.
|
| First look at this picture [0]:
| https://en.wikipedia.org/wiki/Higgs_mechanism#/media/File:Me...
|
| The Higgs field is a complex number Ph (this number can vary at
| different points in space, we'll come back to this, so don't
| worry about it for now). You can imagine it as a ball bouncing
| around on the landscape shown in the image. The higher the
| altitude of the ball, the more energy it has (just like a ball
| in real life). Ph = 0 corresponds to the center of the image,
| the point right at the top of the little hill.
|
| At a high temperature, the ball is jostling and moving around
| like crazy. You can imagine constantly pelting the ball with
| marbles from all directions, causing it to dance eratically
| around the landscape. (Further, the ball doesn't experience any
| friction. It slows down when it happens to get hit by a marble
| that's heading in the opposite direction to it.) In reality,
| there are no marbles, of course, the jostling comes from the
| interactions of the Higgs field with other fields, all of which
| are also stupendously insanely hot.
|
| The landscape in the picture has a rotational symmetry. You can
| rotate it by any angle, and it will still look the same. When
| the temperature is very high, the ball dances across the whole
| landscape. It slows down as it climbs up a slope, so it does
| spend less time at the bits that are at a higher altitude. But
| if we consider a thin ring around the center that's all at
| about the same altitude, the ball is equally likely to be
| anywhere along the ring. The average value of Ph is 0.
|
| As the temperature decreases, the ball's motion calms down, and
| it spends more and more of its time in the deepest valley of
| the landscape. It rarely has the energy to climb high up the
| slopes anymore. Eventually, the ball will start to live on just
| the narrow ring around the center where the altitude is lowest.
|
| Now we come back to the fact that the Higgs field is a field,
| which means it has a value at every point in space, and these
| values can differ from each other. It turns out that all fields
| in physics "prefer" to have similar values at nearby points in
| space. There is an energy penalty for fields that change
| rapidly in space. At high temperature, this didn't matter too
| much. The Higgs field had lots of energy to pay this penalty,
| just like it had lots of energy to climb up the slopes of the
| landscape. So the field here and the field 1nm to the left
| could have wildly different values. At cold temperatures, it
| matters a lot. So the Higgs field has the lowest energy if it
| has the same value everywhere in space. Anything else comes
| with an energy penalty. If we pick a point in space, and try to
| move the field clockwise or counterclockwise around the center,
| the neighbouring points in space pull the field back towards
| the average of the surrounding values.
|
| So at any point in space, Ph is just equal it its average
| value, which is not 0. It's not zero because we have to
| randomly pick a point somewhere along the ring of lowest
| altitude, which is some distance from the central 0. The
| universe has randomly selected a direction in this landscape to
| be "special".
|
| This is the situation from when the universe was insanely hot
| all the way up until the present. Incidentally, if you vibrate
| the ball radially, towards and away from the center of the
| landscape, this vibration corresponds to the Higgs boson.
|
| If we could somehow heat the universe up to a stupendously
| insanely high temperature again, then the special direction
| would disappear, and the average of Ph would be 0 again. This
| is kind of similar to how magnets lose their magnetization if
| heated past a certain critical temperature, the Curie point.
| [1] If we let it cool down again, it would choose a different
| random special direction.
|
| [0] https://en.wikipedia.org/wiki/Higgs_mechanism [1]
| https://en.wikipedia.org/wiki/Curie_temperature
| lainga wrote:
| Very nice explanation! Is it possible that Ph could vary
| smoothly and subtly over space, such that it's a few degrees
| or so away from our value in the Andromeda galaxy?
| idontwantthis wrote:
| 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 wrote:
| 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 wrote:
| 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)
| wyager wrote:
| > 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 wrote:
| 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.
| ..
| simpaticoder wrote:
| The aether (or just ether) was assumed to be the substance
| in which light waves waved, just as air is the substance
| that sound waves. If this substance existed it was likely
| that the Earth was moving through it at some velocity, and
| the Michelson-Morley experiment famously showed that this
| is not so. There were also observations of Jupiter's moons.
| These null results led to Lorentz' quantification of what
| would become Einstein's definition of special relativity in
| 1905.
|
| Our confidence in SR is so strong now that c is _defined_
| and length unit defined as the distance light travels
| during a set time.
| Maxatar wrote:
| That hardly constitutes a precise definition, but at any
| rate the lecture I linked to goes over the history and I
| quote, once again from Einstein himself:
|
| >The next position which it was possible to take up in
| face of this state of things appeared to be the
| following. The ether does not exist at all...
|
| >More careful reflection teaches us however, that the
| special theory of relativity does not compel us to deny
| ether. We may assume the existence of an ether; only we
| must give up ascribing a definite state of motion to it
|
| This is about half way through the lecture before
| Einstein touches on general relativity. Towards the end
| he is quite adamant that a theory of the ether is
| necessary to fully appreciate general relativity.
|
| With that said I do not want to fall into an argument
| from authority, certainly much of what we understand
| about relativity today along with its implications
| differs from its original formulation, but I present the
| lecture because I think a lot of people don't quite have
| the appreciation or historical understanding of what the
| ether was or wasn't, they just read about how the
| Michelson-Morley experiment proved that it can't exist
| along with sensational views that the experiment
| represented some kind of embarrassment or catastrophe in
| physics and the ether became a fall-guy of sorts that we
| must entirely rid ourselves of.
|
| But if you read through the actual primary sources you
| get a very different picture of how physics progressed
| bit by bit.
| simpaticoder wrote:
| _That hardly constitutes a precise definition_
|
| It is precise enough for our purpose: ether is a
| hypothetical medium for light waves to propagate.
| Moreover it would need to have no interaction with
| ordinary matter, or else it would cause planets' orbits
| to decay.
|
| _only we must give up ascribing a definite state of
| motion to it - Einstein_
|
| This is a "No True Scotsman" fallacy wherein one
| redefines the assertion to deal with specific objections.
| I hesitate to criticize Einstein, of course, but in this
| case it's not clear that "ether" minus motion means
| anything. One can be generous and say he had an intuition
| about fields, however fields aren't ether, either.
| Maxatar wrote:
| > ether is a hypothetical medium for light waves to
| propagate.
|
| If that's the extent of your definition then it is not at
| all inconsistent with Einstein's definition of the ether
| in the lecture I linked to.
|
| >This is a "No True Scotsman" fallacy wherein one
| redefines the assertion to deal with specific objections.
|
| Imagine using your argument to claim that atoms don't
| exist because atoms were by definition indivisible
| structures, and so anyone who argues that atoms are made
| up of protons, neutrons and electrons is just engaged in
| a "No true Scotsman" fallacy.
|
| This might be how people on the Internet argue, but it's
| not how curious people make genuine advances in science.
|
| Note that your definition of ether never said anything
| about having a definite state of motion so it's not at
| all clear what exactly you're looking to criticize to
| begin with. Einstein isn't claiming that the ether has no
| motion, just that it's motion adheres to Lorenz
| invariance.
|
| >One can be generous and say he had an intuition about
| fields
|
| Claiming that it's generous that Einstein had some kind
| of intuition about fields is so absurdly laughable that
| I'm not sure there is much more to even discuss on this
| matter. How generous you must be to recognize that Albert
| Einstein had some kind of intuition about fields.
|
| It certainly makes me wonder if people read what they
| write sometimes before hitting the reply button.
| simpaticoder wrote:
| I think you need to review the site guidelines about tone
| and purpose. Moreover, I'd suggest you review the history
| of quantum mechanics, because Einstein did not invent
| field theory, just as Newton did not invent or understand
| the Lagrange or Hamiltonian formulations, nor statistical
| mechanics, even though his theory provided the foundation
| of them all. I'm not a historian of physics, or a
| psychologist, so I will bow out of the conversation. May
| your clear passion for science continue without making
| you hostile.
| Maxatar wrote:
| You're bringing in a bunch of entirely irrelevant topics
| into this instead of actually addressing the points.
|
| My apologies if pointing that out in clear language goes
| against site guidelines, it might be rude to point it out
| but this site does have a problem with people who think
| they know it all and blurting out something as laughable
| as it's "generous to say Einstein had an intuition about
| fields" is in my opinion a prime example of it.
|
| All the best to you.
| eigenket wrote:
| > What was the "specific" definition of the aether?
|
| TL:DR the aether has a reference frame. This is exactly
| what it's inventors wanted and exactly what modern things
| don't have.
|
| Here is the long version:
|
| When you put together a couple of the constants of
| classical electromagnetic theory (specifically the
| quantities called the permitivity and permeability of free
| space) you get out a quantity which has the units of a
| speed. You get this thing which is measured in metres per
| second.
|
| Now if you're a Victorian era scientist, and you have fully
| internalised Gallilean relativity and Newtonian mechanics
| then this is absolutely, completely, insane. There is no
| way in their worldview for a speed to exist in isolation,
| without a reference frame for it to be measured with
| respect to.
|
| If I measure a guy on a bike going at 10 miles per hour,
| and a guy in a car going at 30 miles per hour past him then
| the guy on the bike sees the car going at 20 miles per hour
| relative to him. If I sit opposite you on a train I measure
| your speed to be 0, even though we're both moving at 100+
| km/hour. Speeds are (for Victorian scientists) completely
| relative.
|
| So they have the theory of electromagnetism, which seems to
| be giving amazingly accurate predictions, except that it
| also gives you this apparently absolute speed, which makes
| no sense. Someone realises pretty fast that it's about the
| speed that light goes. So what do they do? They propose the
| existence of this "aether" stuff which is everywhere at all
| times and critically _which has a reference frame_. The
| aether provides a reference frame for the speed of light
| and the crazy meaningless absolute speed they didn 't know
| what to do with now makes sense, it's relative like any
| other speed, but the magic quantity they got is the speed
| in the aether's reference frame.
|
| Of course a few decades later Michelson and Morley show
| that this idea doesn't work, in an incredibly beautiful
| experiment, and the aether theory starts to look shaky. A
| few years after that Einstein (with input from people like
| Lorentz) cooks up special relativity which is _almost_ like
| Gallilean relativity in that _almost_ all speeds are
| relative, except specifically the speed of light is not.
| The speed of light is absolute, just as it has to be
| because of the way it pops out of electromagnetism.
| halyconWays wrote:
| > while QFT fields like higgs are not physical at all
|
| Phew, I feel better now. Non-physical scalar and tensor
| fields permeating all of expanding spacetime in a non-
| physical manner give rise to physical behavior via local
| nonphysical wavefunction collapse that we call excitations.
| criddell wrote:
| That's why the mathematical universe hypothesis (everything
| is built from mathematical structures) seems likely to me.
| halyconWays wrote:
| It's sort of unsatisfying to say that math has the
| ability to experience itself, though
| calf wrote:
| How does something not physical give rise to physical
| properties? Saying that way makes it sounds like a logical
| conceit is being used.
| Zondartul wrote:
| Rule #1 of talking about the aether is "don't call it aether".
| Nowadays it's "spacetime this" and "mass-energy tensor that"
| and "properties of vacuum something else".... and we still end
| up with empty space behaving like a funky fluid.
| ISL wrote:
| The aether originally suggested a preferred reference frame
| -- something thoroughly debunked by tests of special
| relativity.
|
| The universe could still have various preferred/interesting
| frames (the CMB's rest-frame sure is interesting), but it
| won't have much, if anything, to do with the movement of
| particles or light.
| BlarfMcFlarf wrote:
| Notably, though, unlike an aether, none of those things have
| a measurable rest frame.
| cryptonector wrote:
| It's not an aether... I mean, aether was a crutch, but the
| mathematics that Lorentz developed simplified and you just
| don't need aether -- it's enough to assume that there's a
| maximum speed of light and the relativity principle.
|
| (Well, that's only true if you assume there's no as-yet
| undiscovered fields and particles with FTL that we could
| eventually interact with -- then we would be able to get
| something like measurements of speeds of everyday particles and
| photons relative to such fields, and if they were much faster
| than light then those measurements would look like "absolute
| speed" to us. But that's sci-fi fantasy.)
|
| Higgs is not aether for electromagnetic waves. It's only a wee
| bit like aether for matter if you squint real hard, but still,
| it's not a medium of travel for matter, so it's not an aether.
| mfworks wrote:
| 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
| programd wrote:
| 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-ph...
| sieste wrote:
| > 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...
| pdonis wrote:
| _> Is that really so?_
|
| As the article notes, no, this is not a correct description.
| sieste wrote:
| sorry for the confusion, I meant is it really the case that
| this is a commonly used description of the higgs field.
| Sniffnoy wrote:
| I've seen it a bunch, FWIW.
| pests wrote:
| A "tall tale" is one that is likely false.
| tsimionescu wrote:
| 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
| simpaticoder wrote:
| 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.
| russellbeattie wrote:
| > _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.
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