# How/why does spin affect properties of particles?

• Jarfi
In summary, Supersymmetry is a theory that suggests that particles have symmetric partners or something and those partners where exactly the same but they spun slower, so they had different properties, so why does different spin give different properties of particles?
Jarfi
In supersymmetry, particles are said to have symmetric partners or something(dont remember what it was called) and those partners where exactly the same but they spun slower, so they had different properties, so why does different spin give different properties of particles?

I think you have misunderstood the idea of Supersymmetry a little bit. The idea of a particle's "spin" is not a measure of how "fast" or "much" it spins, but rather is a quantum mechanical property of an particle which dictates the number of ways a particle can rotate about its axis. Each spin mode dictates a different Angular momentum and energy state, which are important concepts in QM. Particles with half-integer spin numbers (typically 1/2) are called "fermions" and include electrons, muons, protons, neutrons, neutrinos, etc. Particles with integer spin numbers (often 1) are called "bosons" and are force carrier such as the photon, gluon, W-, W+ and Z bosons. Two other bosons called the graviton and Higgs Boson are theorized but haven't been found. The theory of super-symmetry states that for ever fermion, there is an identical particle of opposite spin.

So, for example, the neutrino is a fermion, of spin number 1/2, Supersymmetry theorizes there is a particle of the exact same mass and charge, but instead of being a fermion of half integer spin, it is now a boson, of integer spin 1. This is called the "neutralino". Every fermion is supposed to have a similarly opposite-spin boson and vice-versa for the bosons. This neutralino would make a excellent candidate for Dark Matter, but alas, not supersymmetric particle have ever been found.

Different spin numbers effect many things, most basically, how a particle spins about its axis, but also dictates the sort of statistics we must use in order to do physics on large amounts of these particles, how particles interact with different energy states, etc. (example, an electron cannot share the same energy state with any other electron, which is seen in electron shells in atoms. However, photons, which are boson actually like to share energy states with other photons, and we can cram many of them into identical energy states, such as a Bose-Einstein condensate.

Hmm so if a particle spins in a different direction it changes its properties, but why?, sry don't really know much about physics, I am still just an amateur noob:(

Jarfi said:
Hmm so if a particle spins in a different direction it changes its properties, but why?, sry don't really know much about physics, I am still just an amateur noob:(

The word spin in quantum mechanics doesn't mean to literally spin, like a top. It is a property which, like soothsayer said,
Different spin numbers effect many things, most basically, how a particle spins about its axis, but also dictates the sort of statistics we must use in order to do physics on large amounts of these particles, how particles interact with different energy states, etc.

It is like any other property, be it charge, mass, angular momentum, etc.

So the spin of a particle is kind of like the particles state/how it behaves

Yep!

It's not *really* the angular momentum of a particle, or how it spins on its axis, it's more of an intrinsic property of a particle that we like to think of as a sort of spin. It's pretty weird quantum mechanical stuff, but it's just as fundamental to a particle as its mass or charge.

Here's a good site I found, With one little typo, the author mentioned photons have spin 0 when in fact they have spin 1, not that important for a gloss over of spin, but it changes things ;)

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soothsayer said:
Yep!

It's not *really* the angular momentum of a particle, or how it spins on its axis, it's more of an intrinsic property of a particle that we like to think of as a sort of spin. It's pretty weird quantum mechanical stuff, but it's just as fundamental to a particle as its mass or charge.

Here's a good site I found, With one little typo, the author mentioned photons have spin 0 when in fact they have spin 1, not that important for a gloss over of spin, but it changes things ;)

Great link, explains alot. Haha i tought they literally meant a spinning spere, but they don't even know what the spin in itself is just some kind of state of the particle, pretty cool how little we actually know about the world

Jarfi said:
pretty cool how little we actually know about the world

Indeed it is! It ensures this physics degree I'm getting won't be totally useless ;)

## 1. How does spin affect the charge of a particle?

The spin of a particle does not directly affect its charge. The charge of a particle is determined by its composition and interactions with other particles, not by its internal spin.

## 2. Why do particles with different spin values have different properties?

Particles with different spin values have different properties because spin is a fundamental characteristic of a particle. It affects how the particle interacts with other particles and fields, as well as its intrinsic angular momentum and magnetic moment.

## 3. How does spin affect the stability of a particle?

The stability of a particle is not directly determined by its spin. However, particles with higher spin values may have shorter lifetimes due to their increased interactions with other particles and fields.

## 4. Why do some particles have half-integer spin while others have integer spin?

This is a fundamental property of particles and is related to the type of particles. Fermions, which include particles like electrons and protons, have half-integer spin, while bosons, such as photons and gluons, have integer spin.

## 5. How does spin affect the behavior of particles in a magnetic field?

Particles with spin experience a torque when placed in a magnetic field, causing them to precess around the direction of the field. This behavior is known as spin-magnetic moment coupling and is responsible for phenomena such as the Zeeman effect.

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