John Carlos Baez4d ago

The Higgs boson gives elementary particles their mass, but 98% of the visible mass in the Universe (not dark matter) comes from a less famous mechanism: chiral symmetry breaking. This is why protons and neutrons are so much heavier than their quarks!

Briefly, protons and neutrons act like bags full of a soup of virtual quark-antiquark pairs, which give them most of their mass. This soup, called a 'quark condensate', breaks a certain symmetry that exists outside the bag: 'chiral symmetry', where you change the phase of the clockwise and counterclockwise rotating quarks separately. In the quark condensate, the clockwise spinning virtual quarks are entangled with counterclockwise spinning virtual antiquarks.

https://en.wikipedia.org/wiki/Chiral_symmetry_breaking

Chiral symmetry breaking - Wikipedia

Show threadnothing4d ago
@johncarlosbaez what does the word 'virtual' mean here ? I don't understand 'virtual particle'?
Show threadJohn Carlos Baez4d ago

@subjectsphinx - that's a long story. Virtual particles are a concept important in quantum field theory, and you have to be a real expert on virtual particles before you can understand how they form a condensate!

Let me see how Wikipedia tries to introduce the concept:

"A virtual particle is a theoretical transient particle that exhibits some of the characteristics of an ordinary particle, while having its existence limited by the uncertainty principle, which allows the virtual particles to spontaneously emerge from vacuum at short time and space ranges. The concept of virtual particles arises in the perturbation theory of quantum field theory (QFT) where interactions between ordinary particles are described in terms of exchanges of virtual particles. A process involving virtual particles can be described by a schematic representation known as a Feynman diagram, in which virtual particles are represented by internal lines.

Virtual particles do not necessarily carry the same mass as the corresponding ordinary particle, although they always conserve energy and momentum. The closer its characteristics come to those of ordinary particles, the longer the virtual particle exists. They are important in the physics of many processes, including particle scattering and Casimir forces. In quantum field theory, forces—such as the electromagnetic repulsion or attraction between two charges—can be thought of as resulting from the exchange of virtual photons between the charges. Virtual photons are the exchange particles for the electromagnetic interaction."

https://en.wikipedia.org/wiki/Virtual_particle

Virtual particle - Wikipedia

Show threadnothing4d ago
@johncarlosbaez the word "virtual" is what i don't understand. in what sense are they "virtual"? what does "virtual" even mean? from that description it sounds like it's just another piece of the same kind in an explanatory framework, not like it's distinguished by some particular quality of virtuality ? if virtual particles are observable, the "virtual" ceases to make sense, so is it an unobservable particle? but then "particle" is also unclear, as it just means part of a whole. but then are we just looking for a noun for every verb? for instance these pieces are distinguished and defined by what they do, not what they are. they are what they do... so ... are we having to introduce virtual particle because we introduced stuff before stuff doing things? whereas perhaps somehow action itself can give rise to stuff? for instance, is a quark just stuff without action doing quark? is it the subject-predicate form of sentences that makes us think each predicate speaks of a subject? well, that would make sense, but it would call into question not just virtual particle, but particle as well; and particle is just part of whole... but then i get confused again because from a bigger system to get a smaller system i take a partial trace which only fuzzily determines the sub system, so that really there are no sub systems precisely determined, only vaguely cut out... and then why are particles distinguished here? it seems to logically not hold together very well.
Show threadnothing4d ago
@johncarlosbaez it doesn't logically hold together in that i can't cut out a part of the whole definitely, and yet i talk of particles, and then go further and call them virtual... maybe the whole way of looking at it is making it more confusing than it has to be?
Show threadnothing4d ago
@johncarlosbaez the whole atomistic picture seems to not make sense anymore? it depicts this bottom up build up from component pieces, but the framework denies that the pieces can exist definitely, because any subsystem is fuzzily determined and not definite, yet claims definite relations between component pieces? well... and i think this relates to the cognizing subject who abstracted away themselves, because the subject says "I think", and so starts with the "I" that thinks and theorizes, and that then bleeds into the whole framework because that one "I" can be recast as "electron" or "particle" or "virtual particle". the form of our thinking ties into our physics and vice versa, each giving the other legitimacy... and then institutions, grants, journals, research papers, conferences, magazines, a whole industry, that then plugs into business, politics, and entertainment, which also affirms this subject-predicate form of thinking reinforces it, and yet... it might all be based on an error. Neumann talked about cascading observations where the final observer is the ego. Neumann said hidden variable theories are impossible, but implicitly assumed locality. Well, it seems the locality, the particality, and the subject-predicate dogma are all linked.
Show threadnothing
@johncarlosbaez oh, it seems like there's a fundamentally outdated concept coming from aristotelian philosophy of substance, so that we think that we can make tables of elements and memorize those and learn something, whereas the elements are labels for processes; and if we just got the processes clear, like for instance symmetry and where it's relevant, then the whole dynamics becomes clear, whereas when we remember quarks and bla bla bla we get into memorizing names and their connections. the body can feel and mirror within itself the whole dynamics of symmetry breaking better than just a loose picture of blobs and sticks between them, which is utterly dead and lifeless...
Mar 25 at 8:01amWeb
Show threadVoid Turtle3d ago
@subjectsphinx "virtual" is just a word physicists slap on it for shorthand, don't read to much into the choice. They are just factors in the terms of the perturbation expansion that look like particle propagators, but their momentum isn't "on the mass shell" ie their momentum doesn't satisfy the energy-momentum relationship of relativity.
Show threadnothing3d ago
@void_turtle thank you. i need to learn so much to understand this better.do you find the philosophy behind it has any value to you? i find it both relevant and interesting, and don't even all it "philosophy" but call it just trying to think about what we're talking about. i know people tend to think the "shut up and calculate" stuff makes more sensee.
Show threadVoid Turtle3d ago
@subjectsphinx I don't like the maxim of "shut up and calculate" at all. Thinking about the meaning of the math is really important imo