this post was submitted on 15 Jun 2023
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Explain Like I'm Five

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What are the Particles and their categories?

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[โ€“] weirdwallace75 8 points 1 year ago* (last edited 1 year ago) (1 children)

The particles are fairly easy:

There's two basic categories of fundamental particle, fermions and bosons, based on what kind of spin they have. Spin in quantum mechanics is a fundamental property; there's no way to stop an electron (for example) from spinning or to give it more spin. Fermions have half-odd-integer spin and so obey Fermi-Dirac statistics, which means there can't be more than one of them in a given quantum state. Bosons have integer spin and so obey Bose-Einstein statistics, which means they can bunch up in quantum states. This leads to electrons, which are fermions, separating themselves into separate electron shells, which results in the solid matter we know and love, and bosonic atoms like rubidium being able to form a Bose-Einstein condensate, which has a lot of interesting properties.

Fermions are divided into quarks and leptons, where quarks are fermions that do participate in the strong interaction and leptons are fermions which do not. There's three generations of each; the quark generations go up and down, strange and charm, and top and bottom, with each generation more massive, and therefore more short-lived, than the previous. All matter you've ever directly experienced is made of up and down quarks, which combine to form protons and neutrons in atomic nuclei, using gluons to mediate the strong force. Leptons may be charged or uncharged, by which I mean electrical charge, and also come in three generations named after the charged "electron-like" lepton of that generation, those being electrons, muons, and tauons. Each of those charged leptons has a charge of -1, and, again, each generation is more massive and shorter-lived than the previous. The neutral leptons are the neutrinos, which only participate in the weak interaction and gravity and, therefore, barely interact with other matter at all. Huge volumes of neutrinos from the Sun ghost right through Earth completely unchanged, night and day. Yes, we have solar neutrinos shining up through the ground on us at night. The neutrinos, while they do come in three generations (electron neutrinos, muon neutrinos, and tau neutrinos), have a very poorly-understood mass; while it cannot be zero, we don't know what it is, only that it's very small, and beneath some threshold value which gets revised downwards every so often.

Bosons are force carriers, and divided into two categories based on mathematical properties beyond even this post. The gauge bosons, all with spin 1, are the photon, which carries the electromagnetic force, the W and Z bosons, which carry the weak force, and eight gluons, which carry the strong force. The only scalar boson, with spin 0, is the Higgs boson, which is one of the things that helps give matter mass.

Particles have antiparticles, which have equal and opposite charges (electromagnetic, weak, and so on) to their opposite number. For example, the electron's antiparticle, called the positron, has an electromagnetic charge of +1. Even neutrinos have antiparticles, which helps balance the books as regards something called lepton number. However, some truly neutral particles, such as the photon, the Z boson, and the Higgs boson, are their own antiparticles.

[โ€“] BackOnMyBS 3 points 1 year ago (1 children)

thank you very much!! I'll think about it and ask follow up questions in the morning ๐Ÿ™‚

[โ€“] weirdwallace75 2 points 1 year ago

I'm sure you will have questions. Physicists still have questions. โ˜บ For example, we don't know why there are three generations of quarks and leptons. Even my very, very brief overview can lead directly into mysteries of the universe.