Inside the Proton
quantamagazine.org
quantamagazine.org
https://profmattstrassler.com/2022/09/09/protons-and-charm-q...
Virtual particles do not necessarily have an invariant mass. That's why you can find examples of typically huge particles inside protons. That's why a beta decay of a neutron can involve the production of a virtual W- boson that has an invariant mass that's 86 times more massive than the neutron.
“A virtual particle is not a particle at all. It refers precisely to a disturbance in a field that is not a particle.”
Not sure how they even apply in the case where Feynman diagrams aren't applicable. Hell, the calculations likely use lattice QCD which eschews them entirely!
On the contrary, this means that there are too many virtual particles (gluons) being exchanged inside a proton, so many that perturbation theory is not applicable.
No doubt, and Casimir is probably sufficient evidence, but it seems to me a lot of confusion would be saved if we changed the name.
To what I don't know - perhaps something like say quantum energy disturbance but more eloquent or descriptive.
Basically, it's like a playing around virtual machine on a physical PC.
I assume that means those "virtual particles" behave almost like actual particles. e.g. have a rest mass or not.
This helps lay person understand physics better.
> In short, atoms are to protons as a pas de deux in a delicate ballet is to a dance floor crowded with drunk twenty-somethings bouncing and flailing to a DJ.
Also check out the comments and comment answers there. Very interesting too!
Science communication, even between scientists, is filled with lies and half truths that shroud the truth in mystery.
Virtual particles are a good example.
Quarks are fundamental is another example.
A proton is made of three quarks is yet another.
But there are countless others I've come across in studying quantum mechanics and relativity.
Could you share a bit more on this?
The strong force is a bit confusing, as it binds boths quarks with the proton and neutron, as well as binding the neutrons and protons into atomic nuclei, over short ranges (accounting for the upper size limit / stability limit of the largest nuclei). Mesons are the force-carrying entity that bind the neutrons and protons together, but gluons are the force-carrying entity that bind the quarks together, as per this wiki article:
https://en.wikipedia.org/wiki/Strong_interaction
Is it the case that theoretical strong-force calculations have just hit a dead-end and there's no way out in sight, due to the coupling constant issue?
> "I just read somewhere that both gluons and mesons transmit the strong force, gluons between quarks inside hadrons, but mesons between nucleons. I thought that the strong force would have one field, and one associated particle, whether inside hadrons, or between nucleons"
Unfortunately, alpha_s is large at low energies, and by low I mean at the atomic and nuclear scale. There you are well and truly in the domain that perturbative QCD is impossible. The only option at that point is something called lattice QCD at the quark/gluon level.
Edit: Typo
* Two loop calculations are extremely challenging on an algebraic level
* You get low energy (called 'infrared red') infinities appearing at low energies. These need to cancel between all your contributing terms, and getting them to cancel is really really challenging.
* The numerical Monte Carlo approaches become extremely computationally intensive because of high dimensional integrals and numerical instability caused by point 2
It was not uncommon for calculations of single terms to involve multiple PhD students over a decade or more.
Throughout my PhD I certainly felt like something was fundamentally 'wrong' with the approach. Alas, I wasn't smart enough to rewrite the field with a whole new way of thinking so bailed instead.
Forgive my ignorance, but what does calculating this sort of look like? I am not a mathematician or even math-adjacent.
* Analytical integrals - This is a big algebraic task where you're trying to compute an equation that can be written by hand. For example, if you have 1-loop diagram [1] then the particle in the loop effectively becomes an integral over all possible momentum configurations that particle can have. One-loop is a hard problem but reasonably 'solved', 2-loops is extremely challenging.
* Numerical integrals - This is typically using Monte Carlo techniques to numerically integrate over all possible momentum configurations of the incoming and outgoing particles. Because you can have many particles, it becomes a high dimensional integral pretty quickly. Monte Carlo scales well with dimensionality, but not that well. Therefore you need serious computation power for non-trivial numerical integrals.
Added to this fact is a fun feature of these calculations that infinities spring up all over the place. You have both a numerical and analytical game of getting these guys to cancel (they do, the calculation must be finite) but it is not a straightforward task at all.
X * ((1/e) - (1/e)) + finite terms = finite result.
Easy right? Only there is a problem: the different terms have different dimensional integrals. You can't just do some alebra to cancel these terms, instead what you have to do is construct something called a subtraction scheme which moves the contributions between your different integrals, such that the subtraction terms don't contribute anything to final result and cancel each other, but render the whole calculation finite. This is a by-hand crafted thing, and takes years and years to calculate properly, which is very easy to get wrong.
The complication in particle physics is actually constructing the equations and evaluating the integrals either numerically or alebraically. The algebraic calculations are extremely hard, and checking you are right is really difficult. Typically that involves two independent research groups attempting the same calculation using different approaches and checking you get the same result.
Similarly, for the numerical evaluation of the integrals you really are pushing what a computer can do to the limits. If we consider the term:-
X * (1/e - 1/e) + finite
and I'm trying to integrate this numerically, you typically put in an artifical cutoff term as you get close to the singularity. Problem is you reach the limits of floating point precision pretty quickly: asking for the difference between two massive numbers is the worst case scenario for numerical evaluation. Trying to work around these problems are really, really challenging.
* There are many more than two terms in a real calculation
I'm guessing the field interaction when a high-energy electron hits a proton is a lot more complicated than the kinetics implied by the description, but "surprising" results are still stated in terms of features of the "particle" produced. It seems like the particle analysis is simply ignoring field interactions that are not (currently) mathematically tractable, so instead of a 3-5 quark zoo in proton, we are witnessing 3-5 types of field interactions (and don't actually know how "many" "types" there are). Is that the case?
Hawking predicted low mass objects could form a black hole, and while the proton has less mass than the minimum bounds he calculated, it is extremely dense. Perhaps it's dense enough to where it's close to a micro black hole such that it "sticks together", but information can still be exchanged at its edges? If it's acting as some kind of interface between our spacetime and a gravitationally collapsed state, then this could possibly explain phenomenon like how quantum entanglement is possible, with information being exchanged across spacetime via these quasi black holes. Just my layman speculation!
Now that we are more-or-less entrenched in the mathematical model of fields, I wonder if anyone is considering vortices within those fields as a possible explanation for observed behavior.
No. Particles are (approximately-)localized excitations in the corresponding field. Think waves, not water balloons.
From the article it wasn't clear to me if these extra high-energy particles they were seeing as fuzz in the data (which are heavier than a photon) are actually unexplained mass or a situation of conservation of energy meets special relativity (kinetic energy -> mass).
If you put enough energy into separating quarks, I'm told you get extra quarks. So an energetic system where the masses don't add up doesn't seem like an epoch defining mystery to me. So what are we missing?
Bound states aren't really made of their constituents in a classical sense. A proton is a particular configuration of the quark fields (really it's more complicated than this), but not a simple sum of quark particle states. And in particular, its mass doesn't have to be the sum of the masses of particle states.
https://www.youtube.com/watch?v=JqNg819PiZY
It's about 1 hour long (plus some questions) and it goes through some basic ideas of what it means for something to have mass and all the way to the Higgs mechanism.
Virtual particles themselves can always be ignored as they are not physical. They're purely a computational method in some approaches. They don't exist in others at all. And even when they are part of the method what kind they are depends. Looking at momentum space? Your virtual particles can have any position. Looking at position? Your virtual particles can have any momentum.
Alternatively: Virtual particle just means that if you have a certain kind of field, what kind of "particles" you need to sum up to get that kind of field. The field itself is the physical thing. Viewing it mathematically as sum of virtual particles is just a mathematical viewpoint.
It's not exactly informative nor true. Yes you can describe the electric field as sum of virtual photons but that's different to a normal photon. And even then the electric field is not the same as the potential energy. Sure it defines it but it's not the same as the potential energy of the charged object.
In case of protons it's the same. It's better to think of it as a field, which it is. Gluon in itself is "just" an excitation of that field. Just like photon is an excitation of the electric field. And the binding energy of the proton comes from the quarks interacting with the gluon field.
The reason I'm talking so much against the virtual particle viewpoint because then people will start thinking of some things whizzing about. That's not what happens. It's a field.
It's actually better to think of even the normal fermions with mass with fields, because that's what they are. It's no longer surprising that how does electron go through both slits at the same time or how all electrons are identical. Of course they are identical as there is just one electron field that has a very specific kind of excitation that propagates.
This is not some random "Look at my weird theory". It's what Quantum Field Theories are. I mostly blame bad science journalism looking at Feynman diagrams (a great mathematical tool, don't get me wrong) that has people thinking too much about virtual particles.
To think of a proton as containing tons of gluons would be a mistake.
Additionally gluons are expected to be massless, they basically come into existence as needed.
Sure you can describe the electric field in that case by a viewpoint where you sum virtual photons together to get said electric field. Whereas a non virtual photon is alltogether a different thing. You can actually describe a normal non virtual photon as a sum of virtual photons.
Point is that virtual particles are just a mathematical tool.
Actual real gluons do exist and they're analogous to the actual photon.
In case of electromagnetism the actual stuff is the electric field. With proton (so in quantum chromodynamics) it's the gluon field. It's called that because every particle has a field and every field a particle. It would be kinda like calling electric field a photon field. Same difference.
In a charged capacitor, there's a lot of electrons on one side, but very few of them on the other. When you close the capacitor, suddenly you get a lot of energy out of it.
https://profmattstrassler.com/articles-and-posts/particle-ph...
There is a very good video of a lecture by Leonard Susskind that explains why energy and mass are interchangeable in this way if you want a more in-depth explanation:
The famous thought-experiment in the regard is Einstein's "photons-box": If you could confine a bunch of massless photons (which only have kinetic energy and momentum) inside a (massless) box made out of mirrors, (he argues) the combined package would have "mass", even though the constituents do not (and the emergent "mass" equals E=m c^2 !). In other words, "mass" is an emergent property of the confined ensemble. All of the forces (especially the strong force), create bound-states which are massive and are the exact analogues of this "photon-box".
So the mass of a proton (mostly) comes from the kinetic energy of its confined (by the strong force) constituents (the quarks and gluons).
What do physicists mean when they "antiquark"? I had it explained to me that it spins the opposite way. Which confused me more, what does it matter that it spins the opposite way? You means it has constructive or destructive interference? If it has destructive interference, why don't particles explode?
In a similar vein, chemistry says that chemistry bonds and antibonds [1]. I can kind get it. But not really.
[1] https://chem.libretexts.org/Courses/SUNY_Potsdam/Book%3A_Org...
The solutions in chemistry are wavefunctions. Wavefunctions give a complex number to each point in space so they may interfere constructively or destructively to give complex numbers of greater and smaller magnitude respectively. The Schrödinger equation can be solved for each atom independently to get one electron wavefunctions named atomic orbitals, and, in molecular orbital theory, these atomic combined to give molecular orbitals which are one electron wavefunctions for the molecule. When the atomic orbitals add up constructively to give a molecular orbital with a higher electron density between the atoms it's a bonding molecular orbital, otherwise it's anti-bonding.
Both quarks and anti-quarks can spin in two ways (even though this spin is not a conventional spin but something special to quantum). When a quark and an antiquark are produced, spin must be conserved, so in pair production each must have opposite spin so the total is zero.
What matters is: can we use this newly discovered sub-structure to do something we couldn't before.
The answer to this was a clear and resounding "yes" when we reached the level of molecules (chemistry, which allows us to do a great many useful things), still "yes" at the level of the atom (atomic energy, transistors, etc...).
It is however unclear that QCD, quarks and inner proton structure reality level have yet produced anything usable to implement our will upon the world.
It may yet happen, but to answer your questions: once the depth we dig at stops producing anything usable by an engineer (string theory, quarks both currently fall into that bucket I think), not entirely sure the digging is philosophically valuable in any way.
I never said quantum mechanics was useless.
That's actually specifically why I mentioned transistors.
However, I don't believe QCD has yet produced anything tangibly usable to do stuff in the world.
The proof is in the pudding: if QCD ever does produce something useful, I'll happily recant.
But my general point was that as we dig deeper and deeper, what we get is exponentially diminishing returns, up and until the point when we'll research stuff that's maybe logically coherent, intellectually satisfying but plainly useless, just like string theory currently seems to be.
My point was that when quantum mechanics first was proposed early last century, I can’t imagine anyone would have even considered LEDs as a thing even in their wildest dreams, yet it was obvious once further progress occurred, and was key in understanding and developing them past the initial ‘that’s odd….’ stages.
We don’t know yet if something similar will come out of QCD (understandable and usable ‘high temperature’ superconductors? Quark matter computers? Super high strength materiel derived from some kind of degenerate matter?) but it definitely seems less likely by the day.
It does at least have falsifiable predictions, so it’s about a billion miles ahead of string theory!
It’s also possible we’ll need another 50 years of engineering or a world war (I hope not) to dig deep enough into areas to discover another, simpler, way to think about it that is more useful.
I still believe looking for things we can use should be a guiding light.
Why would you bring that into the conversation?
Did I mention anything about money?
> Very limiting to couple the pursuit of knowledge to application
Didn't say that either.
I said "useful", and what I meant was "can the knowledge gained be used by us to implement change now or at some point in the future".
As pointed out by another poster, the interesting talking point is that it is hard to guess beforehand whether knowledge gained will ever be useful.
I nevertheless believe in the principle that research should be directed by the hope of discovering something useful, not by the mere pleasure of finding some sort of satisfying "explanation" to the way things work.
But hey, if mine does satisfy you, please let us know what criteria you would use to discover when you've squarely left the area of worthy research to enter that of intellectual onanism.
Somehow I want to think that there's a much simpler layer underneath and all this imperfection comes as a second order side effect.
Plato's cave seems the relevant meme. But is it really complexity a side effect or, as you suggest, is simplicity a side effect of our minds' pattern matching preferences?
That's a good point and I tend to think so. Think about this: pretty much everything (any object or property we observe) is an abstraction. People talk about people who are bad at abstracting and we know what they mean, but actually everyone is abstracting everything. Our actual experience without abstraction is just a bunch of unassociated colors and sensations and whatnot.
There are two questions:
- whether there are laws that describe everything there is to know (e.g., the answer is yes for chess—there are rules that describe it). It is the "fundamental" dimension (particle physics at the moment)
- whether there is something to do once we know all the laws. The answer is yes ("knowing rules do not make you a grandmaster") e.g., we likely know all of the fundamental physics required for turbulence or brains but it doesn't solve these fields (there are interesting unresolved problems). It is the "applications" dimension.
https://www.quantamagazine.org/contemplating-the-end-of-phys...
Other than Occam's razor, why is that assumption considered valid?
Have we verified this experimentally?
Or does some complex piece of math show that only one possible internal structure can lead to similar externally observable behaviors?
Sometimes with not-so-serious results: https://en.wikipedia.org/wiki/One-electron_universe
Now, why are the combinations of 3 quarks the only ones (that we know of, at least) that are stable is a much more complicated question related to properties of the strong force.
There’s nothing wrong with the 3 quark description of a proton, it’s a model, it’s useful up to a certain level of accuracy.
I don't want to make it sound easy, because as the article says, our math lacks the ability to handle the way our current best theories describe it, but it certainly isn't any easier trying to understand QCD through the lens of particles as the fundamental objects. It's really a mess of field fluctuations, and in those field fluctuations we have certain patterns we call "particles", but those patterns can shift and ebb and flow in any number of ways, including in ways we have no intuitions for since our macroscopic intuition keeps wanting to sneak particles in the backdoor despite everything being waves.
Directly understanding what's going on isn't easy, but it's probably still easier than trying to hold on to particle-based ideas.
Or, you know, since none of this matters on a day-by-day basis to hardly anyone, I think just looking at it from the particle point of view and calling it a day is a perfectly viable option. In which case, a proton is three quarks, full stop. It's not 100% correct, but hey, QCD isn't either (still waiting on that Grand Unified Theory), so there's no real harm in stopping at the 3-quark model.
Note that there may well not exist any GUT. However, QCD can't be correct until it also accounts for gravitational effect, so what we're waiting for is a theory of Quantum Gravity that is consistent with both QCD and General Relativity.
In contrast, QM/QFT can't deal with particles curbing space-time, and GR can't explain the movement of elementary particles, so we know for sure those two theories can't be completely correct: there must exist something we're missing to explain how gravity works at the lowest detail level.
* these are already unified to some extent as the electro-weak interaction, which as I understand is believed to be a single kind of interaction at very high energy levels, as seen in the early universe, with 2 different aspects at the lower energies typical of our age. I may be wrong on some of the details here though.
well i guess we'd better give up. what a ridiculous statement.
Like mass and charge and energy and probability
If you know the math you can share it here and say what the terms mean
If you dont know the math then your comment contains the lie that you know what you're talking about and that people should listen to you
2.) You are making grandiose and uncharitable assumptions about the interpretations of things other people said, e.g. equating not having the words to to describe something to implying that we should give up trying to understand it more.
3.) Having a physical definition for every term in an equation does not mean the resulting behavior/phenomenon can be conceptually explained with words. Can you conceptually explain what "spin" is for an electron?
edit to add a bit more: I should also point out that no one introduced a fallacy except you. You are, yet again, stretching other peoples words to build straw man arguments for yourself. I don't remember ever making the claim that the math explains ""what spin is"".
"Can you conceptually explain what "spin" is for an electron?"
I'm sure Meletus felt that way while Socrates was absolutely wrecking him in court and exposing his hypocrisy. Maybe that's why they murdered Socrates?
You are not qualified to take part in the debate I raised. It's obvious you dont understand the little physics you have read nor know the math you're trying to talk about. You should count yourself lucky instead because this conversation is a chance for you to open your eyes to a world of physics which is even more amazing than you realized. Instead you'll probably just keep trolling. 'The starting point of true learning is the realization that you're not actually aware of anything yet.'
> let me know next time you personally observe a quantum phenomenon with your own senses.
to my knowledge, literally every single "sense" measurement is a "quantum" phenomenon which happens via entanglement along with literally everything else at all scales. you still have insufficient understanding of this.
and dont mince words about quantum being a theory and things being beyond theory. you contradict yourself in that way and if consciousness is beyond our science now and that is your point then I invite you to stop arguing with me and will remind you that we are discussing experiments in real life and what physics means, not what I feel in my heart.
please stop now
English/natural language isn't a privileged mode. It's one of many, including math, musical notation, computer code, and chess notation. We use the best language for the context, and who cares that laborious translations are available to others? I could be typing ascii codes in binary, instead of letters right now, but so what?
Please please nail that proton
The moral of too many of my stories is if something is bothering you, track it first before trying to fix it. Because it's easier to get other people to help police a graph than a series of unix commands. And for everyone else you'll get regressions when you're focused on some other priority. Data points like "sometime in the last month" are pretty hard to nail down on a large codebase, especially if it's not a monolith. Last Tuesday around noon is pretty specific.
https://www.reddit.com/r/ProgrammerHumor/comments/6s0wov/hea...
I demand it, really. Why should I put any stock in a god who can't explain (1) where they came from and (2) what endows them with any authority? It's a very low bar for entry.
On just cause ;), cyclical explanations create a giant hamster wheel. Why the wheel at all? So I think he implies the need for a prime mover. I.e. a force outside the system that defines the system. Kinda like axioms are needed to make maths work
Just my 2p
"Why did you punch me in the face?"
"Because if I hadn't, you wouldn't have a broken nose"
That isn't an explanation why the punch happened, it is observing that the nose would not have been broken without a punch.
Someone else (call them the "Evolutionist") responds with the anthropic principle - that, if no intelligent life had arisen in this universe, there would be nobody here to observe that there was no intelligent life. And this is completely logically correct. It is also irrelevant. The Creationist never asserted that it was improbable that life arose in this universe, but rather that it was improbable that it arose purely by naturalistic means. The question isn't whether we're here; the question is how or why.
The Creationist was saying, either we're here by purely naturalistic, evolutionary means, with some probability (call that Pe), or by being created, with some probability (call that Pc). As far as I can see, Pc is unknowable, even in principle. But the Creationist argument is that Pe is so low that it seems reasonable that Pc is higher. That is, it seems reasonable to suppose that we are here due to creation, not just evolution.
The anthropic principle doesn't answer that argument at all. It gives an argument about "whether", not about "how".
Or to put it in different terms: The anthropic principle says something like, if there are a billion universes, and life only arose in a thousand of them, we have to be in one of those thousand to be having this conversation. (Note that I don't actually believe in multiple universes; this is just to make the probability discussion clearer.) But the Creationist never denied that. The Creationist says: Of those thousand universes, if life arose by creation in 998 of them and by evolution in only 2 of them, it seems reasonable to suppose that we're in a universe where life originated by creation, not evolution. The anthropic principle, which asserts that we're in one of the thousand, doesn't address the Creationist's argument at all.
Unless.
It seems to me that everyone who pulls out the anthropic principle in this situation implicitly assumes that Pc is precisely zero. They never explicitly state this assumption, but I think it's there in their thinking. So for the Evolutionist in this conversation, Pe and the probability of life at all are exactly the same, and the anthropic principle does address the actual claim.
But, instead of being irrelevant, in this case the anthropic principle is begging the question. The Evolutionist starts with the conclusion that they are arguing for. That's invalid logic. That's so invalid that, to the degree that the Evolutionist relies on the anthropic principle to support their position, to that degree they should doubt their position.
(I think the Evolutionist pulls out the anthropic principle for an additional reason - it's easy. It lets them "win" the discussion without having to disprove the Creationist's big scary probability number.)
It was about the same time that a family member had died so I was coming to terms with the fear of dying for the first time, so I guess that's what triggered this.
But then again, I've never met anyone who became a believer through observing creation. Just as my confirmation bias leads me to see God in these stories, I imagine unbelievers tend to receive confirmation of the absence of God.
Another interesting question to ponder though: Who's fault is this? Is it God for not jumping out of the shadows screaming "I am he, worship me!"? Or is it an unbeliever who makes assumptions about how a God would act, and finds there is no God because he doesn't fit the unbeliever's assumptions? In which case, what is the unbeliever but a God himself?
In which case, by believing in one specific God, one is not an atheist in any sense toward other religions. Believing in one specific God literally means that you do have "belief in the existence of a supreme being or deities," your only dispute is to which one.
This is word chopping, not an interesting philosophical argument. Truth is exclusionary, and the space of excluded hypotheses is at a minimum exponentially larger than the non-excluded ones, if not super-exponentially, if not some variety of simply infinitely larger, depending on how you count. Appealing to the size of the universe of false statements and/or "things you don't believe" is not meaningful.
LOL.
Did you by chance live in Malaysia towards the end of the 80's ?
[EDIT]: never mind, I see they are still making them in 2022 . Who knew!
reading the privacy policy they say:
> We currently do not honor “Do Not Track” signals.
I guess they mean "care" as in want.
Hence, reality cannot be understood, by design. Reality is chaos, meaning and stability mere perception.
Source: it was revealed to me.
I don't necessarily subscribe to the 'simulation' viewpoint, but that sounds exactly how some lazy evaluation/procedural generation system would work. Don't need to compute values until they are needed. Just like atomic orbitals.
Add that to all the quantization we have discovered in nature, the speed of light limit (which is also the speed at which information can be transmitted), the time dilation effects with speed... and that provides plenty of food for thought.