[HN Gopher] Proton's mass radius is apparently shorter than its ...
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       Proton's mass radius is apparently shorter than its charge radius
        
       Author : raattgift
       Score  : 164 points
       Date   : 2023-04-03 23:33 UTC (23 hours ago)
        
 (HTM) web link (arstechnica.com)
 (TXT) w3m dump (arstechnica.com)
        
       | drdeca wrote:
       | The article refers to a gravitational something tensor, and, I'm
       | wondering whether that is because this is actually dealing with
       | gravitational effects, or whether it is just called that because
       | it is the same tensor (or basically the same, or analogous in
       | some way) to the stress energy tensor?
       | 
       | It also isn't obvious to me what "mass radius" ought to mean...
       | 
       | I guess like, the average distance from the center of the mass,
       | but like...
       | 
       | Idk, I guess that makes sense..?
       | 
       | But I guess I'm not sure what the "meaning" of that quantity
       | would be? Like, what makes that a relevant quantity for
       | describing the system? Is it in case you are hoping to describe
       | some gravitational effects? Or...?
       | 
       | Hmm... well, I guess one could ask the same question about the
       | "charge radius"... but that one to me sounds like it would have
       | clearer uses? Like, if you are describing the EM forces on/from a
       | charge, then the charge being distributed over a region would
       | have different results than if it were at a single point I'd
       | think.
       | 
       | Though, "the center of the proton" also doesn't have one single
       | position either.. but I imagine one could kind of separate those
       | two things, comparing "what if we had a point particle with the
       | charge and mass of a proton (which of course would be in a
       | superposition over a range of positions)" to "what if we had a
       | proton, with charge distributed about the center (and the center
       | distributed over a range of positions in the same way as the
       | hypothetical point particle)"
        
         | joe__f wrote:
         | Quoting from the article (which quotes from the paper):
         | 
         | "Note that I am not even attempting to find an analogy for the
         | gluonic gravitational form factors that would help you
         | understand them. They're described in the paper as "the matrix
         | elements of the energy-momentum tensor of the proton"
         | 
         | The energy momentum tensor is the same as the stress energy
         | tensor.
        
         | evanb wrote:
         | A good cartoon is that a form factor is the function that
         | describes how an object deforms when exposed to an outside
         | influence with a particular momentum. The form factor is a
         | function of momentum.
         | 
         | There are many different kinds of outside influence. They can
         | be scalar (think: just increasing the pressure uniformly),
         | vector (put in an electric field), tensor (zap with a
         | gravitational wave), pseudovector (magnetic field),
         | pseudoscalar (zap with a pion).
         | 
         | Of course, you can apply a scalar outside influence and a
         | vector at once. But the scalar, vector, tensor, pseudovector,
         | and pseudoscalar labels denote different representations of the
         | Lorentz group [lorentz].
         | 
         | What's more: the Wigner-Eckhart theorem [wigner] basically says
         | [cheat] that the response can be factored into three pieces:
         | the strength of the external influence, a factor that depends
         | only on the representation of the external influence, and a
         | factor that depends only on the property of the thing you're
         | talking about (a proton, in this instance).
         | 
         | So people _call_ it the gravitational form factor because if
         | you exposed the proton to a gravitational wave, it 's the thing
         | you need to know about the proton to know how it deforms.
         | 
         | Note that because of the factorization you don't actually have
         | to zap the proton with a gravitational wave! You can measure it
         | by zapping the proton with other stuff, as long as you can get
         | that stuff to have the right rotational properties or measure
         | the response to many different perturbations and sum the
         | responses the right way to mock up a tensor operator. The
         | experiment at JLab doesn't use gravitational waves, it uses
         | these latter approaches.
         | 
         | Roughly speaking at zero momentum the form factor is the
         | _charge_ of the object you measure if it 's just sitting there.
         | So the electric form factor evaluated at zero momentum is the
         | electric charge, the gravitational form factor evaluated at
         | zero momentum is the mass.
         | 
         | What are radii? Express the form factor as a function of
         | momentum^2 [possible]. In units that physicists like to work in
         | (where c=1, hbar=1), the units of momentum are 1/length. Expand
         | the form factor as a Taylor series in momentum^2 and you will
         | get                   form factor(p) = charge + # radius^2 p^2
         | + ...
         | 
         | where # is a known dimensionless number.
         | 
         | The above story is a cartoon but can be made more-or-less
         | precise depending on how much quantum field theory you learn.
         | 
         | lorentz:
         | https://en.wikipedia.org/wiki/Representation_theory_of_the_L...
         | 
         | wigner:
         | https://en.wikipedia.org/wiki/Wigner%E2%80%93Eckart_theorem
         | 
         | cheat: this is a little bit of a cheat, it's only true to
         | leading order in a taylor series in the strength of the
         | external influence.
         | 
         | possible: it's always possible to arrange this, or at least to
         | separate the momentum dependence into a factor dictated by the
         | rotational symmetry properties and another factor dictated by
         | the object, just like in the Wigner-Eckhart theorem.
        
       | hibbelig wrote:
       | It would have been nice to get some idea about the relative
       | sizes.
        
         | iamerroragent wrote:
         | It's really really tiny and rather incredibly small.
         | 
         | https://arxiv.org/abs/2102.00110
         | 
         | " Collaboration data to extract the r.m.s. mass radius of the
         | proton Rm=0.55+-0.03 fm. The extracted mass radius is
         | significantly smaller than the charge radius of the proton
         | RC=0.8409+-0.0004 fm. "
        
           | hibbelig wrote:
           | So the charge radius is about 150% of the mass radius. Thank
           | you.
        
           | gus_massa wrote:
           | So 0.55/0.84 = 0.65, i.e. 35% smaller.
        
             | plank wrote:
             | If charge is surface* effect, and mass a 'volume' effect,
             | you might expect a ratio of 1.0/(0.5^[1/3]).
             | 
             | This is 1.26 (or 0.79). Does not seem to fit experiment,
             | even when fiddling with error bars. OK, so no volume vs
             | surface effect then. *Suppose that both gluon and quarks
             | are really in the exact same region, but that the
             | 'effective' behaviour is "on the surface" for one of them,
             | while "in the whole volume" for the other. In three
             | dimensions, the "effective" radio would differ, in one it
             | would be a factor (0.5)^(1/3) smaller.
        
             | dr_dshiv wrote:
             | Charge radius is 53% bigger, got it.
        
               | pacaro wrote:
               | It's almost as if the charge radius is in miles and the
               | mass radius is in kilometers. It's imperial vs metric all
               | the way down
        
           | jcims wrote:
           | For scale, the mass radius of the proton is roughly to one
           | millimeter as one millimeter is to the diameter of the sun.
        
             | mywittyname wrote:
             | This is very helpful to understanding the sheer magnitude
             | of the scale. I previously had no concept of the size of a
             | ten thousandth of a femtometer.
        
               | jcims wrote:
               | (Not a big deal but the .03 is the tolerance not the
               | power.)
        
       | narag wrote:
       | _The proton is a collection of quarks and gluons moving at
       | relativistic speeds around a central point._
       | 
       | What? Moving at relativistic speeds? I had never heard that.
        
         | arethuza wrote:
         | _" Each of these particles, or "nucleons," is composed of a
         | dense, frothing mess of other particles: quarks, which have
         | mass, and gluons, which do not. Yet the quark masses only add
         | up to a mere 1% of a proton or neutron's mass, with the bulk of
         | the proton mass coming purely from the motion and confinement
         | of quarks and gluons."_
         | 
         | https://physics.aps.org/articles/v11/118
        
           | narag wrote:
           | So the interior of baryons is analogous to the interior of
           | atoms, with gluons instead of electrons dancing
           | frantically... weird.
           | 
           | Also the part about mass being generated by motion and how it
           | seems to be an established fact.
        
             | nimish wrote:
             | Not really. The "roiling sea of particles" is a metaphor
             | for perturbation series, which very specifically does not
             | work for the strong force at low energies.
             | 
             | Take anything involving virtual particles as just that,
             | virtual. They're an aid for computation and cannot be
             | observed directly. They aren't necessary either; lattice
             | gauge theory is always applicable if not practical.
             | 
             | The mass(-energy) being from the strong interactions is
             | still true. And the residual bit of the strong force
             | between protons and neutrons works with the virtual
             | particle/perturbation theory approach pretty well, using
             | pions.
        
               | tines wrote:
               | I'm glad you brought this up, because I've been reading
               | some stuff lately that makes it seem like virtual
               | particles actually have visible effects, like this one:
               | 
               | https://www.forbes.com/sites/startswithabang/2019/07/12/y
               | es-...
               | 
               | So is it that these articles are wrong, or that I'm
               | reading them wrong, or that the idea that virtual
               | particles are just for calculations is outdated?
        
               | antognini wrote:
               | My impression is that the notion of "virtual particles"
               | is a bit of an outdated concept. There isn't really as
               | much of a physical distinction between "real" and
               | "virtual" particles as there is sometimes made out to be.
               | All particles are excitations of some underlying field.
               | Generally speaking, these excitations can have some
               | resonance that allows them to persist for long durations.
               | This resonance occurs when the particle is "on the mass
               | shell" in the jargon --- that is, it has a rest mass that
               | is equal (or at least extremely close) to the observed
               | mass of the particle. Excitations that are "off the mass
               | shell" decay exponentially. But these other excitations
               | do have real observable effects. The Casimir effect is
               | the most famous, but they're also responsible for the
               | Lamb shift and Hawking radiation which have also been
               | observed.
        
               | nimish wrote:
               | No, it's a pretty well-defined concept when you stick to
               | its technical definition as an aid in interpreting terms
               | of a perturbation series as Feynman diagrams.
               | 
               | > these other excitations do have real observable effects
               | 
               | Yeah, that's the major thing: virtual particles explain
               | observable effects in a sort-of intuitive way.
               | 
               | But you could (to my knowledge) get the exact same
               | results without involving any virtual particles, via
               | lattice gauge theory. Since you get the same observable
               | results without them, virtual particles, IMO, shouldn't
               | be considered fundamental to any effect, even if they
               | make the explanation a lot easier.
               | 
               | Anything involving complicated interactions with
               | relativity like Hawking-Unruh stuff has an even bigger
               | issue since the notion of a particle/vacuum is observer
               | dependent.
        
               | l33tman wrote:
               | All post-classical effects in quantum field theory arise
               | from various "corrections" that come from what you could
               | define as virtual particles, whether it's from the
               | perturbative treatment or a numerical lattice gauge
               | calculation. In the latter, you need to (formally) sum
               | over all possible field configurations, the majority of
               | which will contain half-witted weird off-shell
               | "particles" and the entire spectrum between stuff you'd
               | never see as a particle and the classical resonances.
               | 
               | It is more clearly visualized in a perturbative
               | expansion, for sure, but it's a bit disingenous I think
               | to argue that there are no virtual particles in a lattice
               | calculation.
        
               | Chabsff wrote:
               | Hawking radiation has been observed? When did that
               | happen?
        
               | antognini wrote:
               | It's been observed in sonic black holes, which are
               | mathematical analogs of gravitational black holes in
               | fluids (though to be fair the experiment has been
               | disputed, so the evidence is not absolutely unambiguous):
               | 
               | https://www.nature.com/articles/nphys3863.epdf
        
               | Chabsff wrote:
               | Thanks for the clarification.
               | 
               | I don't have the background to be confident about this,
               | but aren't the predicates on which Hawking Radiation is
               | based on part of the equivalency framework between sonic
               | and "real" black holes?
               | 
               | If so, then while the observation of Hawking radiation in
               | the model is certainly interesting, calling it an
               | observation of Hawking radiation with regards to real
               | black holes sounds like a stretch.
        
               | so-and-so wrote:
               | Yeah, the 'Standard model of particle physics' actually
               | states that particles don't exist and there are only
               | fields around.
        
               | marcosdumay wrote:
               | What a bad piece of journalism, intent on confusing
               | instead of explaining.
               | 
               | Virtual particles were invented because they have
               | measurable effects. Physicists don't go around inventing
               | invisible things for no reason. What they are not is
               | "particles". The particle facade is only there because it
               | fits the math.
               | 
               | (The article seems to be describing an experiment that
               | measured energy-time uncertainty.)
        
               | tadfisher wrote:
               | We discovered the mesons by photographing their tracks on
               | plates exposed to the sky. They're real, just extremely
               | short-lived.
        
               | cwillu wrote:
               | Incomplete analogy that's probably a better starting
               | point: if the tone of a bell is a particle, then the
               | other movements of the bell that don't resonate are
               | virtual particles. Now, imagine we called the thermal
               | motions of that bell "virtual tones", and you have an
               | idea why physicists always sigh and emphasize that
               | virtual. particles. are. not. particles.
        
               | nine_k wrote:
               | If virtual particles "fit the math" the same as real
               | particles, what makes them not real? What do they _not_
               | fit?
        
               | nimish wrote:
               | You don't _need_ them, and IIRC _can't_ (in general) use
               | them if you deal with non-perturbative effects, unless
               | you do stuff like re-summing infinite series of diagrams
               | and that really makes interpreting the ultimately
               | observable effect in terms of virtual particles
               | interacting difficult.
        
               | burnished wrote:
               | An example that comes up in semiconductor is the 'hole'
               | virtual particle. It is the absence of an electron. It is
               | not a real and independent phenomenon. But you can treat
               | it like a particle just fine
        
               | gizmo686 wrote:
               | Electron holes are quasi particles, not virtual
               | particles.
        
               | evanb wrote:
               | What makes particles travel long distances as lumps is
               | that they are on-shell. Virtual particles are not on
               | shell.
               | 
               | https://en.wikipedia.org/wiki/On_shell_and_off_shell
        
             | marcosdumay wrote:
             | You meant gluons instead of photons? Because the things
             | analogous to electrons and the nucleus are the quarks.
             | 
             | Anyway, the similarity is only on the level of "it's a
             | bunch of moving things locked together by a force". Those
             | things are about as similar to themselves as they are to
             | planetary motion.
        
             | squeaky-clean wrote:
             | > Also the part about mass being generated by motion and
             | how it seems to be an established fact.
             | 
             | That's what they mean by relativistic speed. When effects
             | from special relativity become large enough that you need
             | to account for them in your math and measurements. There is
             | a difference between invariant mass (aka rest mass) and
             | relativistic mass, which depends on the object's velocity
             | relative to the observer.
             | 
             | https://en.m.wikipedia.org/wiki/Relativistic_speed
        
             | Melatonic wrote:
             | I have no good background in this but could it not be that
             | from an outside observer view the motion appears as mass
             | but when thought of modeled within it is instead
             | energy/motion ?
        
           | ProAm wrote:
           | The Strong Force and Strong Nuclear Force are so utterly
           | fascinating to read about. Gluon Flux Tubes! Seems like pure
           | science fiction and imagination.
        
         | SideburnsOfDoom wrote:
         | This article was around recently: "Inside the Proton, the 'Most
         | Complicated Thing You Could Possibly Imagine'"
         | 
         | https://www.quantamagazine.org/inside-the-proton-the-most-co...
         | 
         | https://news.ycombinator.com/item?id=33262637
        
         | daveguy wrote:
         | I think that just means "moving fast enough that relativity is
         | significant and has to be accounted for". It doesn't mean they
         | are right at the speed of light (although they could be, I
         | don't know). You could call a rocket "moving a relativistic
         | speeds" because relativity has to be included in the
         | calculations for accurate missions within the solar system.
        
           | frutiger wrote:
           | Gluons are massless so they must move at the speed of light.
           | However they are strongly interacting with quarks and
           | themselves so their worldlines will be a crazy mess of
           | intersections.
        
           | bgirard wrote:
           | I wonder what the cut off speed is for relativistic speeds.
           | If you think about it, it's not only a matter of speed but
           | also how much precision you want in your calculations. Even
           | if something was moving very slowly, you need to account for
           | relatively if you want very accurate calculations.
        
             | shagie wrote:
             | You also get some relativity with some elements. Gold is
             | the one that I recall most readily.
             | 
             | Relativistic Effects and the Chemistry of Gold - https://li
             | nk.springer.com/content/pdf/10.1007/BF03215471.pdf
             | 
             | > In atoms of high nuclear charge (Z), as a consequence of
             | a relativistic effect, the s electrons of an atom become
             | more bound and their orbitals smaller than if this effect
             | were absent. Simultaneously, the d (and f) electrons are
             | less bound because of this effect, which scales roughly as
             | Z2. Gold exhibits a large relativistic effect. This
             | accounts for gold being more resistant to oxidation than
             | silver. It also accounts for higher oxidation states being
             | more accessible in gold than in silver. These effects are
             | illustrated by some fluorine chemistry of gold and silver.
             | 
             | https://en.wikipedia.org/wiki/Relativistic_quantum_chemistr
             | y
             | 
             | > Relativistic quantum chemistry combines relativistic
             | mechanics with quantum chemistry to calculate elemental
             | properties and structure, especially for the heavier
             | elements of the periodic table. A prominent example is an
             | explanation for the color of gold: due to relativistic
             | effects, it is not silvery like most other metals.
        
             | quchen wrote:
             | A rule of thumb in classical mechanics is that 0.1c is when
             | you should start taking (special) relativity into account,
             | I think it's 0.5% contribution then.
             | 
             | For general relativity I don't know such a cutoff rule of
             | thumb. Astronomy-wise, Mercury is the only planet that is
             | obviously general-relativistic (its orbit is not an ellipse
             | because it's so close to the sun). On Earth, we don't have
             | strong/inhomogeneous enough gravity, so unless you're
             | synchronizing satellites or atomic clocks, GR is not
             | something to worry about.
        
               | thfuran wrote:
               | Some of the most precise clocks can actually measure
               | precisely enough that a few feet of elevation change
               | makes a measurable difference, which I expect also means
               | that what you've placed under the table it's on also
               | could.
        
               | vkou wrote:
               | Mercury's orbit is absolutely an ellipse. It is
               | _incredibly_ elliptical, with an apogee of 69.8 million
               | km, and a perigee of 46 million km.
               | 
               | The relativistic effects on Mercury concern its
               | _precession_ - the way that elliptical orbit rotates [1]
               | around the sun. And it 's not caused by Mercury's speed
               | (Which is only ~59 km/s at its maximum, compared to the
               | Earth's 30 km/s). It's caused by spacetime being curved
               | by the immense gravitational field of the sun.
               | 
               | If Mercury had a circular orbit, it would have no
               | precession.
               | 
               | [1] Precession is akin to spinning a hula hoop around
               | your body - with the hula hoop representing an orbit.
               | https://en.wikipedia.org/wiki/Apsidal_precession
        
               | joe__f wrote:
               | I think a good rule of thumb is 'check what accuracy you
               | need your answer to, and then include all effects
               | relevant to that precision'. If you needed an answer
               | accurate to four significant figures, then you'd include
               | relativistic effects for v < 0.1 c
        
               | bawolff wrote:
               | I don't think that fits the definition of rule of thumb.
        
               | asah wrote:
               | As a rule of thumb, I like to define my definitions
               | first. /s
        
             | thfuran wrote:
             | Even if something isn't moving at all (relative to your
             | reference frame of choice), you might still need to care
             | about local gravity's effect on time.
        
         | archgoon wrote:
         | For a back of the envelope calculation we consider the
         | uncertainty principle
         | 
         | Dx*Dp >= /2
         | 
         | Dp = D(m _v) >= /(2_Dx)
         | 
         | m = 9.1 * 10 ^ -31 kg (mass of electron)
         | 
         | x ~= 1 * 10^-15 m (radius of proton)
         | 
         |  = 6.6 * 10 ^ -34 kg m^2 / s (plancks)
         | 
         | Dv >= 31 524 512 m /s
         | 
         | Which is about 1/10 the speed of light. There isn't a true
         | cutoff for "relativistic speeds" but in general, 1/10th counts.
        
         | pharrington wrote:
         | The specific composition of baryons is fairly niche physics.
         | Assuming you're not educated in quantum physics, there's as
         | much reason to expect to know about that as there is to expect
         | a non-programmer to know about the minutia of different manual
         | memory management strategies.
        
       | AnimalMuppet wrote:
       | TL;DR: Most of the mass comes from the energy of the strong force
       | interactions of the gluons, not from the quarks. The gluons are
       | not charged; the quarks are. The quarks sometimes go beyond the
       | region of most of the gluons, which gives the proton a larger
       | charge radius than mass radius.
        
         | pavel_lishin wrote:
         | > _The quarks sometimes go beyond the region of most of the
         | gluons, which gives the proton a larger charge radius than mass
         | radius._
         | 
         | This is one hypothesis, but not a stated fact in the article.
        
           | AnimalMuppet wrote:
           | Fair. On the other hand, the charge can't be coming from the
           | gluons, nor from the strong force itself, so it kind of _has_
           | to be coming from the quarks. (Um, unless it 's inducing
           | virtual pair production out there, and the destruction
           | mechanism involves the pair getting destroyed by interaction
           | with the quarks, and it takes one of the pair longer than the
           | other... something like that could lead to charge out there
           | farther than the quarks actually go.)
        
         | blueplanet200 wrote:
         | nit: gluons aren't electrically charged. They carry strong
         | charge.
        
         | phkahler wrote:
         | Why are gluons needed to hold quarks together. If the 3 are in
         | a line, equally spaced, with the oddball charge in the middle,
         | they will attract quite strongly.
         | 
         | +2. -1. +2
         | 
         | If these charges are equally spaced, the attraction of the
         | middle one in stronger than the repulsion of the outer two.
        
           | dguest wrote:
           | Good point! But it's also an unstable system: the -1 will get
           | attracted to one of the +2 charges and (from a distance) look
           | like a +1, and the other charge will fly off to infinity.
           | 
           | I guess we could design a bunch of picometer-scale scaffolds
           | that hold everything in place and this might work, but that
           | doesn't seem to be the way nature put things.
        
             | phkahler wrote:
             | Sure, but what if they're orbiting the center charge at
             | relativistic speeds? Now they also create a magnetic field.
             | My guess is that somehow it ends up being dynamically
             | stable. Also that the strong force holding the nucleus
             | together is actually mostly magnetism.
             | 
             | I would also posit that just maybe there is such thing as
             | an electrostatic black hole. When matter is accelerated
             | gravitationally to speed c, you reach an event horizon.
             | Same should happen if the acceleration is due to charges,
             | but will happen at a scale similar to the size of baryons.
             | I'd say there is a lot of room for some theoretical
             | developments in this area.
        
               | thriftwy wrote:
               | Stuff will only keep an orbit if it has nothing else to
               | do, i.e. if it is dynamically stable.
        
           | blueplanet200 wrote:
           | It's not necessarily a questions of "need". Physicists are
           | just measuring what protons ARE. Whether or not gluons and
           | the strong force are necessary to form an object that looks
           | like a proton is a separate point from what protons actually
           | look like in our universe.
           | 
           | To your point on if such an arrangement would be possible or
           | not ignoring the strong force, it would not. The "net-charge"
           | viewed from the +2 quark would be repulsive, resulting in an
           | unstable arrangement of matter, even if you could construct
           | it in an equilibrium state it would be the unstable kind.
        
             | 988747 wrote:
             | [dead]
        
           | ArchieMaclean wrote:
           | The strong force is much stronger than the Coulomb (charge)
           | force.
        
         | sharikone wrote:
         | In fact gluons have a QCD charge, they just don't have a QED
         | (electric) charge. That QCD charge is basically one color and
         | one anticolor, minus the trace. So there are 8 different basis
         | vectors that define the space for what the charge of a gluon
         | is.
        
       | sebzim4500 wrote:
       | This is not surprising given my own (presumably horribly wrong)
       | mental image of what a proton is. Is it surprising given current
       | theoretical models?
        
         | mannykannot wrote:
         | In your your mental image, was the mass radius necessarily
         | smaller than the charge radius? If so, then your model has
         | survived an empirical challenge. If not, then you have learned
         | something new that was not fully determined or explained by
         | your model.
        
         | etrautmann wrote:
         | I feel that it's important to point out that a scientific
         | result doesn't need to be surprising in order to be important
         | and grounding for future work. I agree this aligns with my
         | intuitions (to the extent that I have any for subatomic
         | particles), but it seems important to document and measure
         | these properties.
        
       | JPLeRouzic wrote:
       | It looks like the questions about electron's mass at the end of
       | the XIX century.
       | 
       | https://en.wikipedia.org/wiki/Electromagnetic_mass
        
         | bbarnett wrote:
         | Some help for you, citizen.
         | 
         | https://m.youtube.com/watch?v=fjFaKD9BuOc
        
           | DoctorOetker wrote:
           | I don't see the relevance of your comment, would you mind
           | explaining?
        
             | peterfirefly wrote:
             | It's "19th century" in English. Many (all?) Romance
             | languages + a few of the other ones in Europe use Roman
             | numerals for centuries.
        
               | nine_k wrote:
               | I think it's styled "XIX" and not "19" to make it look
               | archaic.
        
               | int_19h wrote:
               | In those languages it is used in all contexts and for all
               | centuries. It's just a formatting convention that is
               | occasionally helpful in e.g. history textbooks.
        
               | JPLeRouzic wrote:
               | Thanks, English is not my native language, today I
               | learned something!
        
       | teovall wrote:
       | I really wish articles about physics or mathematics, especially
       | ones aimed at non-experts like this one, would include the
       | English name or pronunciation of symbols and terms. Not all of us
       | know Greek or advanced mathematics and I need something to say in
       | my head as I read along. How do you say J/ps meson?
        
         | archgoon wrote:
         | Jay-sigh
        
         | garyrob wrote:
         | [flagged]
        
           | Groxx wrote:
           | Message boards are currently being inundated by low-effort,
           | low-value, "yeah Google surfaces that Wikipedia page too,
           | much faster, and has for years" drive-by advertisements for a
           | paid service.
           | 
           | It's not really surprising that people aren't excited about
           | that.
        
             | garyrob wrote:
             | OK. My guess was that the person I was responding to didn't
             | know that for $20/mo they could get all the answers they
             | want to questions like the one they were asking (even if
             | not always perfect), and do so immediately and
             | effortlessly, and so pointing it out could be useful to
             | them.
             | 
             | I say that because I know that if I was unaware of the
             | cost/benefits and somebody told me that, that might have
             | motivated me to try it, and it might make a big difference
             | to me. Someone could have added to my productivity and
             | helped my stress level by pointing it out.
             | 
             | In any case, I don't think I'll post about the cost/benefit
             | of ChatGPT on HN again! Thanks for the explanation. I
             | appreciate your taking the time to give it rather than just
             | voting me down. It was kind of you.
        
               | mort96 wrote:
               | They weren't asking a question. They were critiquing the
               | article. And the criticism is perfectly valid. Shilling
               | for an OpenAI subscription is wholly unnecessary here.
        
               | Groxx wrote:
               | To be clear, I (and I suspect many others) _do_
               | appreciate the  "this is from chatgpt [and therefore may
               | not be correct]" notes. Because posting it without that
               | _and without verification_ is what some are doing, and
               | that 's just plain malicious karma farming. Yours isn't
               | that.
               | 
               | But personally I'd like it better if it weren't used
               | period, outside "ai is useful / produces trash"
               | discussions where its output is directly relevant. If I
               | want a machine's answer, I know how to get it, but I'm
               | here for discussion with humans.
        
         | bgirard wrote:
         | It would become redundant very quickly I think. Reading stories
         | about quantum computing feels this way. The first 3 paragraph
         | include the same 'qubits can exists as a 0, 1 or a
         | superposition' over simplification followed by a single
         | paragraph of explanation of the new discovery.
         | 
         | IMO it's much easier for you to answer your specific question
         | with an easy search than it is for article authors to
         | anticipate every question and keep answering it in every
         | article.
        
           | stronglikedan wrote:
           | You'd just have to define the pronunciation once per article,
           | like we do with acronyms.
        
             | squeaky-clean wrote:
             | Don't know why you're downvoted, this is exactly what
             | they're asking for. You don't have to explain the details
             | of the J/ps meson, just the first time you write it in the
             | article put "J/ps meson (J/Psi meson)
             | 
             | For the qubit example, they're not asking for the article
             | to always describe what a qubit is, just if you're going to
             | only write it as "a|0>  + b|1> " it would be helpful to put
             | (qubit quantum state) the first time you do so in the
             | article.
        
           | BobbyJo wrote:
           | Someone use GPT to automatically annotate articles with
           | domain specific knowledge so that I can highlight
           | words/sentences/symbols/formulae/etc. and have it explain it
           | to me.
        
             | gtop3 wrote:
             | This feels like the type of thing I want human expertise
             | on. GPT can be too inaccurate for something like this. I'd
             | also be concerned it was trained on writings from people
             | that misunderstand the science.
             | 
             | There's already tons of expert written and reviewed content
             | designed to teach science. Go buy any textbook on the
             | subject. You can usually get them very cheaply if you don't
             | mind older editions. Libraries will also have these types
             | of books you can checkout for free. Once you've exhausted
             | information found in textbooks you can start actually
             | reading the scholarly journals these pop-sci articles are
             | written about. Once you've read enough scholarly journals,
             | you might have your own questions that aren't answered yet.
             | Then, you can conduct your own science......
             | 
             | Books are great for looking up quick tidbits of information
             | too. Chapter titles and indexes are great for jumping to
             | relevant information.
        
               | BobbyJo wrote:
               | I'm not a physicist, so keeping around a good deal of
               | reading material (not to mention seeking out a good
               | explanation) to understand the odd reference or two seems
               | horribly cumbersome.
               | 
               | Google is way lower friction, but even that requires some
               | manual sorting through.
               | 
               | Seems like exactly the thing a good language model would
               | be great at. If they can't do that, where the stakes are
               | low and the task is exactly the domain of LLMs, then I
               | don't see how they'd be useful for anything.
        
               | gtop3 wrote:
               | I'm optimizing for accuracy and depth of understanding.
               | Your optimizing for lower friction.
               | 
               | I think I'm optimizing for the correct variables.
        
             | bgirard wrote:
             | There was a news site that did something like that, I don't
             | recall which. It was incredibly distracting and I think
             | they started annotating ads in their popovers as well.
        
               | BobbyJo wrote:
               | This is why it's have to be a separate lyer from the page
               | itself. Otherwise it would become yet more add real
               | estate.
        
           | Teever wrote:
           | In the /r/SpaceX subreddit there is an acronym bot that will
           | scan articles or posts for acronyms and make a post that
           | explains the acronyms that it found.
           | 
           | Such content doesn't need to be right in the beginning of an
           | article, it could be linked to or at the bottom of the page.
        
             | bgirard wrote:
             | That's a good example. I found it handy when I was new to
             | the subreddit and it's easily ignored at the bottom of the
             | thread.
        
         | oneshtein wrote:
         | Play the audiofile here:
         | https://en.wikipedia.org/wiki/Greek_alphabet#Letter_names
        
         | meindnoch wrote:
         | On macOS: select letter "ps" - right-click - "Look Up" - it is
         | pronounced "psi"
        
           | squeaky-clean wrote:
           | The real scourge is articles that use embedded images for the
           | greek symbols or other equations.
        
         | otikik wrote:
         | You can always retaliate by using the wrong name on purpose:
         | the Jason meson, the Fork meson.
         | 
         | It will drive them crazy.
        
         | giardini wrote:
         | The J is pronounced as an English "J" ("jay").
         | 
         | ps - psi - pronounced "psaai" (as in "top side") or "saai" (as
         | in "side").
         | 
         | from "Pronunciation of the Greek alphabet in English":
         | 
         | https://jakubmarian.com/pronunciation-of-the-greek-alphabet-...
        
           | mLuby wrote:
           | Interesting link, though I question some of those: taw &
           | p'saai--it's not p'sai'onics right?
           | 
           | And I wonder how useful symbols like ae @ ^ are to people
           | asking how to pronounce Greek.
        
             | eindiran wrote:
             | There is an international, widely-recognized standard
             | alphabet for precisely specifying the pronunciation of
             | things in arbitrary languages, and you are unsure of why it
             | would be useful for people trying to figure out how to
             | pronounce something? Visit the wiki page for each IPA
             | symbol and there will be recordings and examples and you
             | can learn how to read it instead of complaining that people
             | are using the correct tool for the job. The real problem
             | with the linked page is that it is only using IPA half the
             | time...
        
             | int_19h wrote:
             | It's even worse - in English, "psionics" would be normally
             | pronounced something like /saI'on.Iks/.
             | 
             | Generally speaking, the Great Vowel Shift did quite a
             | number on anything originally Latin or Greek.
        
       | raattgift wrote:
       | See also <https://profmattstrassler.com/articles-and-
       | posts/largehadron...> (2011)
       | 
       | Preprint of Nature paper: https://arxiv.org/abs/2207.05212
       | 
       | HTML5 version: https://ar5iv.org/abs/2207.05212 ("x"->"5" opens
       | up ar5iv.labs.arxiv.org).
        
         | yonixw wrote:
         | Wow! What a rabbit hole finding a proton is not just 3 quarks!.
         | 
         | Suggesting these 2 articles:
         | 
         | 1] Experimental results of proton collision as of 2013 (3
         | quarks is an observation, but for low energies) :
         | 
         | https://physics.stackexchange.com/questions/81190/whats-insi...
         | 
         | 2] Another article from the same author (Matt Strassler).
         | Suggesting to read his answers for the comments of: Harry
         | Bostock, Bob Anderson, and the 2 top comments of "aa. sh." (for
         | more history and Neutron decay)
         | 
         | https://profmattstrassler.com/articles-and-posts/largehadron...
        
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