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How Many Elementary Particles Are There, Really?

quantamagazine.org

41–50 of 160 posts

Re: How Many Elementary Particles Are There, Really?

#41

Stopped reading after "Yet in the mathematical equations that define the Standard Model, the eight gluons are distinct from one another in the same way that the W and Z bosons differ." W and Z bosons, photons, etc have fixed masses, charges, interaction strengths with other particles. These properties can exactly be listed and looked up in a table of elementary particles with discrete rows. Gluon color is continuous…

[deleted]

Re: How Many Elementary Particles Are There, Really?

#42

Stopped reading after "Yet in the mathematical equations that define the Standard Model, the eight gluons are distinct from one another in the same way that the W and Z bosons differ." W and Z bosons, photons, etc have fixed masses, charges, interaction strengths with other particles. These properties can exactly be listed and looked up in a table of elementary particles with discrete rows. Gluon color is continuous…

Huh, I didn't even know we had sub-species ID of gluons now

Re: How Many Elementary Particles Are There, Really?

#44

Stopped reading after "Yet in the mathematical equations that define the Standard Model, the eight gluons are distinct from one another in the same way that the W and Z bosons differ." W and Z bosons, photons, etc have fixed masses, charges, interaction strengths with other particles. These properties can exactly be listed and looked up in a table of elementary particles with discrete rows. Gluon color is continuous…

The gluon with color (|g1> + |g2> + |g8>) / √3 is just a superposition of the gluons with colors g1, g2 and g8, the same way you can make superpositions of any other particles. You are right that the choice of basis vectors is arbitrary, but that doesn't make it wrong to count the number of dimensions. It also doesn't make it fundamentally different than, say, polarizations of photons or even flavors of quarks. You can have superpositions of photon polarizations or quark flavors.

All of these are continuous properties in an n-dimensional vector space.

Re: How Many Elementary Particles Are There, Really?

#45
post #6

Not being a Physicist, I have to wonder if all these particles are somehow manifestations of a simpler thing. Might there have been a point in time (long ago) where the “wave photon” and the “particle photon” seemed like possibly different things?

You don't have to wonder, because they are. They're manifestations of fields. I think it is a reasonable answer to tell people "if you're looking for the short list of simplest things, the number of types of fields there are is probably what you're looking for". That doesn't invalidate this question in general, though the number of different answers from people looking at the same thing suggests it may be underspecif…

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Re: How Many Elementary Particles Are There, Really?

#46
post #6

Earlier quoted context omitted.

You don't have to wonder, because they are. They're manifestations of fields. I think it is a reasonable answer to tell people "if you're looking for the short list of simplest things, the number of types of fields there are is probably what you're looking for". That doesn't invalidate this question in general, though the number of different answers from people looking at the same thing suggests it may be underspecif…

But of course one can then question why are there exactly N different types of fields, with their specific types of interaction (at least in our universe)? Why should we suppose that this is the most fundamental description of reality, rather than being emergent from something else?

To me it looks like the periodic table. There's an underlying set of levers in terms of quantum characteristics of fields, but not all settings of these levers are stable. This is just like how only atoms with certain combos of protons and neutrons and electrons are neutral and stable.

If you look at histogram plots of protons, neutrons, and stability, it's not a perfectly idealized form. It's a rocky plot. This emerges from the quantized nature of reality.

So a periodic table of particles (fields) that looks kind of weird and ad-hoc to us is the expected result.

What we don't yet fully understand is really two things as far as I know. First, we know less about why these particular values are special. For the periodic table we actually understand this pretty well. Second, we do not know if there are other islands of stability or particles-fields we cannot see (e.g. WIMPS). For the periodic table we are pretty sure there are no large islands of stability at higher weights. Not 100% sure, but if they do exist there's probably only a few exotic mega-atoms that could be stable, not many.

Re: How Many Elementary Particles Are There, Really?

#48

Stopped reading after "Yet in the mathematical equations that define the Standard Model, the eight gluons are distinct from one another in the same way that the W and Z bosons differ." W and Z bosons, photons, etc have fixed masses, charges, interaction strengths with other particles. These properties can exactly be listed and looked up in a table of elementary particles with discrete rows. Gluon color is continuous…

And the different charge W bosons are just the same particle, via time reversal symmetry.

Re: How Many Elementary Particles Are There, Really?

#50

Stopped reading after "Yet in the mathematical equations that define the Standard Model, the eight gluons are distinct from one another in the same way that the W and Z bosons differ." W and Z bosons, photons, etc have fixed masses, charges, interaction strengths with other particles. These properties can exactly be listed and looked up in a table of elementary particles with discrete rows. Gluon color is continuous…

8 color indices, why not call that 8 particles what is the point of commenting like you are better than the article when you so clearly show you are not in one sentence never speak on physics again please
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