[HN Gopher] Swirling Forces, Crushing Pressures Measured in the ...
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Swirling Forces, Crushing Pressures Measured in the Proton
Author : headalgorithm
Score : 88 points
Date : 2024-03-14 14:25 UTC (8 hours ago)
(HTM) web link (www.quantamagazine.org)
(TXT) w3m dump (www.quantamagazine.org)
| optimalsolver wrote:
| Continuing on this path of scientific enquiry, will we at some
| point finally understand what this is all about? Why there should
| be such a thing as a proton, and why it has the properties it
| does?
| drpossum wrote:
| If you feel like this article is pretty empty in terms of
| "answers" and "new directions" and the fact that research group
| has been pushing these ideas for years, again, without any
| breakthroughs or challenging present understanding, what do you
| think that means for the quality of the research? This is at
| best a "ok, neat" result with some science journalism
| overreaching of how relevant it is for gravity.
| devmor wrote:
| Do you think that all science is useless if it does not
| produce some incredible feat overturning all understanding of
| the universe?
| drpossum wrote:
| No, but I did come from that field and I'm tired of seeing
| this exact article every few months
| lostemptations5 wrote:
| Maybe I'm ignorant, but I follow this stuff abit and it's
| the first time I see something like it.
| drpossum wrote:
| This was the last one
| https://news.ycombinator.com/item?id=39163447
|
| and a paper from last year
| https://arxiv.org/abs/2310.11568
|
| and basically the same paper from three years ago (you'll
| recognize one of the plots from the last article)
| https://arxiv.org/abs/2104.02031
| NoMoreNicksLeft wrote:
| I think, in fact, that there might be more than one proton.
| fsmv wrote:
| Maybe conceivable with electrons since they're fundamentally
| simple but protons are made of other things and can be broken
| while other protons remain so I don't think it's possible
| there could be only one.
| NoMoreNicksLeft wrote:
| Imagine living in a universe where someone broke the one
| proton. Now we have to sit here for eleventy eternities all
| disincarnate waiting for new laws of physics to congeal.
|
| "Honestly, are you never going to let this go? I had goo
| reason to think there was more than one proton!"
| wredue wrote:
| Some things just "are". There is no "why". There is a "how",
| and we may never be able to answer that question.
| blueprint wrote:
| You shouldn't say there is no why if you simply don't know.
| You should say I don't know what the why is yet. Otherwise,
| you might actually believe yourself. I can tell you the why
| for some of those things that you had no idea had an
| explanation before. it's like how doctors used to say, there
| is no cure for X for years and years until at last it turns
| out that there are multiple treatment pathways.
| drdeca wrote:
| > You should say I don't know what the why is yet.
|
| I think this seems to make the opposite assumption, which
| also seems questionable.
|
| Rather than "I don't know the 'why' ", I think it would be
| better to say "I don't know if there is a 'why', nor what
| it is if there is one." .
|
| Though, really, I think the question of "why" in this
| context, is a little unclear as to what exactly it is
| asking?
|
| Like, what properties would a statement have to have in
| order to be a satisfactory answer to the question?
|
| Like, if something like color confinement is inevitable
| assuming SU(3) symmetry, would this answer "why" hadrons
| exist? Or, if the fact by itself wouldn't, would this fact,
| along with a mathematical proof of it, arranged in a way
| reflecting the core ideas of the proof, constitute a "why
| hadrons exist"?
|
| Or, is the question asking something more, like, "why is
| there something rather than nothing?" ? Is it asking for
| the first cause?
| blueprint wrote:
| > Rather than "I don't know the 'why' ", I think it would
| be better to say "I don't know if there is a 'why', nor
| what it is if there is one." .
|
| Yes, very nice! But I didn't want to go down that
| rabbithole as you actually need more correction
| factors... because a person who doesn't know, doesn't
| know if they know or not. ;) But functionally, they can't
| say they "know" - they are not conscious - so they don't
| know if they know or not, and they don't know what
| knowledge they have may contain a "why" or not, etc.,
| i.e. there is great knowledge in history but people don't
| realize or have forgotten what resides in their own
| consciousness or history yet.
|
| > Though, really, I think the question of "why" in this
| context, is a little unclear as to what exactly it is
| asking?
|
| Also very good. 'how' and 'why' converge. That's why a
| person should make clear what they're asking. Just
| because 'why' and 'how' converge doesn't mean 'why' is
| meaningless or useless. In fact, why does something exist
| is different from how, since any "how" explanation is
| implicitly about a process of existence, yet a "why"
| sometimes explains mechanisms that do not "exist" yet
| cause what exists. That's why understanding this and
| enunciating it perfectly is a little beyond human
| eyesight for now. Philosophy exists for a reason and it's
| not just bullshit some thinkers made up (nor does it
| culminate with some semi-Wittgensteinian cop-out that
| words are the best we can do. What a nonsense self-
| contradiction).
|
| Why means many things. People should stop conflating them
| and ask one by one concretely what they want to know if
| they truly want to know. But many people can't even
| realize what their real questions are without some
| dialogue.
|
| Why there is something rather than nothing is that
| nothing can't exist. One little modern explanation: the
| moment you put boundary conditions on, you get virtual
| particles. QFT is clear about that. Without boundary
| conditions or a metric, there is no way to even consider
| the notion of a vacuum or nothingness.
|
| Answering your question involving SU(3) symmetry requires
| you understand why/how SU(3) is pre-determined.
|
| The place where "why" and "how" diverges is when
| involving a subject: "why am I alive" vs "how am I
| alive". The second one is a lot easier to answer if you
| consider only the biological. If you don't understand
| what the point of life is, it will be a lot harder to
| understand your distant past and a lot harder to
| understand your ultimate "why" i.e. your path and your
| purpose in this life. Consider what you know, for
| starters: you are like a child in this universe, growing
| up and learning through your life. When someone has to
| learn and grow, it means they're on the path to
| realization, mastery, and complete knowledge. I'll leave
| it at that for now.
| innagadadavida wrote:
| Had there been any scientific studies into why the elements are
| perfect and there are are all apparent to perfect replicas with
| not defect rates? It's hard to make perfect replicas at scales
| higher than the atomic scale but at the lowest levels,
| everything seems to be identical.
| cjameskeller wrote:
| Couldn't one say that different isotopes of elements are
| exactly such "imperfect" replicas?
| dexwiz wrote:
| Isotopes and elements are human made labels based on
| nucleon and proton counts. Hydrogen and deuterium are both
| the same element, but are obviously different nuclear
| structures. Even at a chemical level deuterium is
| appreciably different. That difference between isotopes and
| elements diminishes but never disappears as atomic mass
| rises.
|
| Isotopes are only imperfect in the context of one labeling
| system. But not from a quantum viewpoint.
| jmole wrote:
| I'm not a physicist, but isn't this 'everything is identical'
| model fundamentally incompatible with quantum mechanics?
| There seems to be hidden quantum state encoded within the
| proton and other subatomic particles, although that state may
| not be relevant to the interactions that we care about on a
| day to day basis.
|
| Your comment does remind me of this though:
| https://en.wikipedia.org/wiki/One-electron_universe
|
| If we are not in a one-electron universe, every electron is
| unique in the sense that it has an entirely unique path
| though spacetime, and thus can't be identical. I think what
| you mean is that every one of these "particles" seems to obey
| the same set of laws, which is not something that's unique to
| atoms, subatomic particles, or even larger things like
| molecules.
| drdeca wrote:
| > isn't this 'everything is identical' model fundamentally
| incompatible with quantum mechanics?
|
| No, quite the opposite, actually. Some particles being
| identical is core to many quantum mechanical ideas. The
| distinction between Bosons and Fermions fundamentally
| relies on this idea.
|
| Also, it probably isn't true that all electrons have
| individual well-defined paths through spacetime.
|
| Electrons are Fermions.
|
| When two electrons are "in orbit" around a helium nucleus,
| with the atom including the electrons being in the lowest
| energy state, the two electrons are orbitals distinguished
| by their spin, but, at least if it were not for the
| interaction with the magnetic interaction from the spin of
| the nucleus, you could choose any axis along which to
| consider the spin direction of the electrons, and like, you
| would get for each of the two spin directions along that
| axis, one of the electrons would have its spin in that
| direction. But considering different axiis for the spin,
| you would be splitting the two up in different ways?
|
| I'm fairly confident it isn't possible to assign a
| consistent id for each electron which persists through
| time. (Even setting aside the "they don't have well-defined
| positions" aspect)
| vundercind wrote:
| Science doesn't really answer "why". It's better at "how".
| postalrat wrote:
| I'd say science can't answer "how" but can answer "when".
| joquarky wrote:
| I find Alan Watts to be informative in pondering these kind of
| questions, as "why" isn't really in the realm of science.
| bmacho wrote:
| Probably we will at some point. It _is possible_ that it will
| _turn out_ that our whole world _is_ , say an ever growing
| finite system with a simple rule. Say someone identifies some
| laws ruling the digits of pi, that's a _physics_ , then they
| look more, and they observe that the CMWB pattern on the sky is
| in the pi too, and voila, we live in pi _confirmed_ (or at
| least it would make it very plausible). Then protons exist, and
| protons are the way they are, because some properties of the
| circle.
| notamy wrote:
| The methods scientists come up with to test things like this are
| absolutely incredible, wow.
| rkowalick wrote:
| I remember being blown away when I was told about Henry
| Cavendish's attempt to calculate G (the gravitational constant)
| in the late 18th century:
| https://en.wikipedia.org/wiki/Cavendish_experiment
| hkwerf wrote:
| "Attempt" may be an understatement, as it worked.
|
| We hat this experiment set up in one of our lecture halls
| once a year. They had to fence off the area and it had to
| relax for days, but we were able to replicate the measurement
| during our introduction to physics lecture.
|
| There was also a lab course on a smaller version. (Video of
| it, in German though:
| https://m.youtube.com/watch?v=8W8X71wW8F0)
| AnimalMuppet wrote:
| I ran the experiment in an undergrad physics lab. When we
| ran it, we had to disable the elevator down the hall for
| vibration reasons.
| abecedarius wrote:
| Same guy who discovered, among other things,
|
| > the concept of electric potential (which he called the
| "degree of electrification"), an early unit of capacitance
| (that of a sphere one inch in diameter), the formula for the
| capacitance of a plate capacitor, the concept of the
| dielectric constant of a material, the relationship between
| electric potential and current (now called Ohm's law) (1781),
| laws for the division of current in parallel circuits (now
| attributed to Charles Wheatstone), and the inverse square law
| of variation of electric force with distance, now called
| Coulomb's law.
|
| (Wikipedia)
|
| Wonder what went wrong to need so many rediscoveries by
| others. Reminds me of Gauss.
| at_a_remove wrote:
| At that time, you have three big candidates: terminology,
| language barriers, and speed of propagation.
|
| I might also include a certain scientific isolation. Not in
| the sense of isolationist tendencies, rather that there
| were a lot of blind men reaching across the elephant and
| their hands had yet to touch.
| DFHippie wrote:
| From wikipedia:
|
| > Because of his asocial and secretive behaviour, Cavendish
| often avoided publishing his work, and much of his findings
| were not told even to his fellow scientists. In the late
| nineteenth century, long after his death, James Clerk
| Maxwell looked through Cavendish's papers and found
| observations and results for which others had been given
| credit.
| api wrote:
| It's kind of like creatively debugging the universe,
| constructing weird scenarios to explore the edges of things to
| fill in missing terms in a model.
| ecommerceguy wrote:
| As humanity continues to peel back the layers of reality, I sure
| feel more and more like maybe this indeed is a simulation.
| morkalork wrote:
| Here, see this and relax:
|
| https://i.imgur.com/x2BzFRB.jpeg
| drdeca wrote:
| All of those before the simulation, seem like fairly useful
| metaphors, that describe something real about the world.
|
| Indeed, there are many things about the world that go in
| cycles. Indeed, much of how the world behaves can be seen as
| acting according to exact, "mechanical", rules (like, the
| laws of physics), etc. .
| ThrowawayR2 wrote:
| On the bright side, finding out that we are all in a simulation
| would at least provide the answer to the perennial question
| about the meaning of life, dohohoho.
| fsmv wrote:
| How can it make sense to measure the stress-energy tensor of a
| proton given that we have no theory of quantum gravity? Are they
| somehow ignoring quantum mechanics?
| vlovich123 wrote:
| This is preliminary work. The bigger issue is that this is
| happening at energy scales that ignore things like gluons.
|
| > Sharper gravitational maps of both the proton's quarks and
| its gluons may come in the 2030s when the Electron-Ion
| Collider, an experiment currently under construction at
| Brookhaven, will begin operations.
|
| It would be hard to imagine the scientists are ignoring quantum
| effects since light + proton screams quantum, so it's unclear
| from the reporting alone if the lack of a quantum gravity
| theory is enough to make all this not particularly useful or if
| this is just bad reporting and the experts are confident this
| is the right way to do things "for reasons". My guess it's
| probably a mixture because the modelled answer computed from
| equations and the measured result seem to be aligned.
| avpix wrote:
| They are measuring the distribution of energy within the
| proton. General relativity (GR) describes how a distribution of
| energy distorts spacetime. They could take these measurements
| of the proton (if they're complete enough) and compute its tiny
| effect on the curvature of spacetime with non-quantum GR.
| Quantum gravity only becomes relevant at the Plank length
| (~10^-35m) which is still much smaller than the proton radius
| (~10^-15m) or the resolution of their measurements.
| misja111 wrote:
| > .. a graviton, the hypothesized particle that conveys the force
| of gravity
|
| I thought it was the Higgs boson that was doing this? But
| obviously I misunderstood something. Could anybody explain what's
| the difference between those particles?
| Firaxus wrote:
| I believe the Higgs boson is what generally gives particles
| mass, which is different from particles which create fields and
| forces?
| AnimalMuppet wrote:
| The Higgs boson (or maybe the Higgs field?) gives mass to
| everything else. The graviton creates the attractions between
| masses.
| zdragnar wrote:
| Higgs boson conveys mass. Mass is not necessary for a gravity
| field. Massless particles such as photons can convey both
| gravity fields and momentum.
|
| In short, gravity is correlated with energy density, which
| coincides with mass (via e=mc2) but the mass itself is not
| directly responsible for the gravity field, per se.
| ginkgotree wrote:
| I'm "positive" this will be a great read.
| perihelions wrote:
| I'm glued-on to my computer screen!
| phkahler wrote:
| They show the forces tangential to the surface of the proton,
| going around one way near the "surface" and the other way in the
| middle. However, the hairy ball theorem says there must be
| something like "poles" in this case.
|
| https://en.wikipedia.org/wiki/Hairy_ball_theorem
|
| I'm wondering if their proton map covers that, and if the "axis"
| corresponds to anything familiar.
| jeffwass wrote:
| Below quote from your wiki link. I'm not a graphics guy, but
| would appreciate if someone with experience in computer
| graphics could please give an example of this common problem.
|
| "A common problem in computer graphics is to generate a non-
| zero vector in R3 that is orthogonal to a given non-zero
| vector. There is no single continuous function that can do this
| for all non-zero vector inputs."
| arbitrandomuser wrote:
| i might be misunderstanding , but it seems easy if you want a
| vector orthogonal to A , generate a random vector B non co-
| linear to A and take AxB (cross product). AxB is orthogonal
| to A .
| perihelions wrote:
| Right: and that's not a single, continuous function that
| works for all inputs--specifically, it fails on the input B
| itself. BxB = 0.
|
| Any solution will have a discontinuity in its output vector
| angles. I don't know how this problem is applied in
| computer graphics, but you probably want to avoid rendering
| objects in the vicinity of a discontinuity: you'd get some
| kind of flickering artifact when you cross it, with small
| e-displacements being amplified into something much larger.
| itishappy wrote:
| This does not work on all non-zero vectors, hence your "non
| co-linear" comment. If the vectors point in the same
| direction, the cross product is zero, and you have an extra
| degree of freedom when choosing your "up" vector.
| itishappy wrote:
| Humans have an intuitive understanding of "up", so there's
| usually a single obvious way to orient a camera when taking
| photos. However, what happens when you point a camera
| straight up or down? There's no longer an obvious choice, any
| direction you choose is reasonable (orthogonal)!
|
| Another way to think about it is assigning cardinal
| directions to the Earth. Which way is north from the north
| pole? There's no possible way to create a map that has
| defined directions at every point.
|
| The pictures in the Wikipedia article give a great intuitive
| understanding, particularly if you can figure out why a
| sphere and torus behave differently. (You can build a
| globally consistent map on a torus.)
| bmacho wrote:
| > (You can build a globally consistent map on a torus.)
|
| No, you can not, there is no global map on the torus.
| itishappy wrote:
| My language may be imprecise.
|
| What I mean is that you can assign a direction to each
| point of the torus, and have it be consistent with it's
| neighbors (free of discontinuities) throughout the entire
| surface. This is in contrast to a sphere, which will
| always have tufts (poles) at at least one point.
|
| Note that this only applies within the surface itself,
| not to it's embedding in 3d space (the donut shape we're
| all familiar with). If north points up on the outside
| edge, it'll point down to us on the inside edge, but an
| ant on the surface would experience no contradictions.
|
| https://en.wikipedia.org/wiki/Torus#/media/File:Torus_cyc
| les...
| bmacho wrote:
| What example of what common problem? That's a true statement,
| and its proof is right above it, in the wiki page?
| Aerroon wrote:
| Is this a consequence of tan(90) being undetermined?
| (approaches +infinity from one side and -infinity from the
| other)
| a1369209993 wrote:
| > There is no single continuous function that can do this
|
| Nitpick: that should be "no single continuous _deterministic_
| function "; it's (relatively) very easy to sample _uniformly
| randomly_ from the unit circle orthogonal to a given non-zero
| vector, but that won 't give, for example, approximately the
| same result on two consecutive video frames, such that you
| could usefully orient the camera with that direction "up".
| owendlamb wrote:
| The image halfway through the article says the forces are
| "twisting shear forces," which "twist one way [or] the other"--
| only two ways to twist!
|
| Maybe by "twisting" the author means that the field is one of
| torques rather than of linear forces. I guess you can make a
| continuous field of torques tangent to the surface of a sphere
| (as long as you're speaking of the "wheel" of the torque, not
| its pseudovector axis, being tangent to the sphere).
|
| In addition, you can only speak of two "ways" any particular
| torque in such a field can go: clockwise or counterclockwise,
| as viewed from, say, a point inside the sphere. That would
| explain the one-way-or-the-other language.
| antognini wrote:
| If I understand their diagram correctly I would guess that it
| is somewhat nuanced. Those shear forces are probably related to
| the internal angular momentum of the proton. But in quantum
| mechanics you cannot precisely measure the axis of a particle's
| angular momentum. You can only measure the total magnitude and
| the component along one axis. Because of this there wouldn't be
| any regions you can point to that are "poles" where there is no
| angular momentum.
| neovialogistics wrote:
| It's not applicable. The theorem applies to the boundary of
| 1+2n dimensional balls - surface of an ordinary sphere, bulk of
| a 5-ball, 6-surface of a 7-ball, etc.
| vecter wrote:
| Why does the proton not meet this criteria?
| neovialogistics wrote:
| I see where my post above was unclear. For the theorem to
| apply to a 1+2n dimensional object, the vector field on the
| 2n dimensional surface of the object must be restricted to
| the surface - it must be tangent to the object everywhere.
|
| The proton is fully 3-dimensional AFAICT so the vector
| field on the surface (if it has a surface, I'm not a
| physicist) can have non-tangent components, pointing
| inwards or outwards.
| api wrote:
| Is there a relationship between the intense forces here that are
| apparently balanced and stable and the fact that mass is
| equivalent to insane amounts of energy (via E=mc^2)?
|
| Is mass basically a ball of balanced forces ready to explode if
| this balance is disrupted?
|
| If so then it seems interesting that this tension's potential
| energy maps exactly to mc^2.
| itishappy wrote:
| I think what you're describing is called the stress-energy
| tensor, which as I understand it is a generalization of mass.
|
| https://en.wikipedia.org/wiki/Stress%E2%80%93energy_tensor
| mrkstu wrote:
| Since matter is basically precipitated energy from the near
| infinite energies released by the Big Bang, makes sense to me
| that it has fairly high amounts of energy compacted.
|
| If nothing else, nuclear bombs made this blindingly obvious.
| pitherpather wrote:
| It is true in general that the "binding energy" of a nucleus is
| reflected in the measured mass or atomic weight, exactly as
| mc^2.
| dustingetz wrote:
| > They found that in the heart of the proton, the strong force
| generates pressures of unimaginable intensity -- 100 billion
| trillion trillion pascals, or about 10 times the pressure at the
| heart of a neutron star. Farther out from the center, the
| pressure falls and eventually turns inward, as it must for the
| proton not to blow itself apart.
|
| This is inside each of us, 100 billion billion billion times
| kazinator wrote:
| > _"It's a tour de force," said Cedric Lorce_
|
| I see what he did there.
| froza wrote:
| I always wonder, how exactly are gravitons or gluons supposed to
| create the attraction between two particles? They carry a
| negative momentum or its just magic? Does it mean that the
| gravitational force is fluctuating with some statistical
| distribution of gravitons?
| antognini wrote:
| Thinking of a virtual graviton or photon or gluon as a particle
| is somewhat misleading. It is better to think of it as an
| excitation of the underlying field.
|
| It is possible to show (with fairly elementary techniques) that
| when the excitations have a spin of 2, these excitations always
| reduce the energy of the system, and so produce an attractive
| force. If the excitations have a spin of 1, then they increase
| the energy of the system and so produce a repulsive force. This
| is why the gravitational force attracts and like charges repel
| each other.
| AnimalMuppet wrote:
| > If the excitations have a spin of 1, then they increase the
| energy of the system and so produce a repulsive force. This
| is why the gravitational force attracts and like charges
| repel each other.
|
| But then why do _unlike_ charges attract? The force mediator
| is still a spin-1 particle...
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