A beam would split into three parts in a Stern-Gerlach experiment. Follow-up on this answer. Learn more physics!

**Spin-1/2 - Wikipedia**

Related Questions. Still Curious? Dear Tridib, This is a very deep and fundamental question. He came back the next day and said "I can't do it. That means we don't really understand it". See, for example:. LeeH If you go on in physics, after you've learned some special relativity and quantum mechanics, you should get to learn the spin-statistics theorem, which at least tells why particles have either half integer or full integer spin, and why the hlaf are fermions and the latter are bosons.

### Spin (physics) - Wikipedia

So far as I know, the current state of theory doesn't account for much of that. The "Standard Model" puts many of these features in by hand. What is known is why particles have to have hzlf integer or half-integer spin, and why the former must be bosons and the latter must be fermions. We've discussed that a bit in answers on spin-statistics.

Spin is an intrinsic form of angular momentum carried by elementary particles, and thus by composite particles and atomic nuclei.. Spin is one of two types of angular momentum in quantum mechanics, the other being orbital angular casinocanli.co orbital angular momentum operator is the quantum-mechanical counterpart to the classical angular momentum of orbital revolution and appears when . D5 Two spin one-half particles. States of two spin 1/2 particles. Tensor product states. Product states and entangled states. Operators on tensor product vec. Description: In this lecture, the professor talked about spin one-half states and operators, properties of Pauli matrices and index notation, spin states in arbitrary direction, etc. Instructor: Barton Zwiebach.This probably doesn't answer your question, so please pne up if you can specify more what you are after. When particles have spins that aren't whole, I read you only have to spin them that much to see the same side, so an electron you only spin it a half a rotation and you see the other side.

### The Feynman Lectures on Physics Vol. III Ch. 6: Spin One-Half

What causes this? Or was the book wrong? This noe is confusing me a lot, and seems impossible to me. Wow, what was the name of that book?

### Wavefunction of Spin One-Half Particle

It sounds as if it got things seriously confused. What changes as you rotate a particle like that is something more abstract, its quantum phase, a complex number that rotates in the complex plane. Sorry if those are unfamiliar concepts, I just can't think of some other way to describe it. Anyway, here's the part that's really opposite to what you got from that book.

A particle with a whole-number integer spin comes back to the same state after rotating around once. A particle with half-integer spin comes back to minus its starting state after a whole rotation.

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It has to rotate twice to get back to the starting state. Alright, I am beginning to understand why you need to rotate an electron twice to see the same side again, however, if you had 2 electrons, and rotated them against each other, such as 2 gears would, would this affect the spin?

Would it prevent the spin from being "weird"? The complex probability amplitudes are something of a theoretical construct which cannot be directly observed. Observable states of the particle are then **spin** by the one operators S xS yand S zand the total spin operator S. For example, the spin projection operator S z affects a measurement of the spin in the z direction.

Thus, linear combinations of these two states can represent all possible states of the spin, including in the x - and y -directions. From Wikipedia, the free encyclopedia. Type of matter. Classical mechanics Old quantum **half** Bra—ket notation Hamiltonian Interference.

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You're right that electrons are not rotationally invariant. I guess if you wanted you could then say that means they have "sides", although I think you can see that the resulting picture would be pretty misleading.

Download the video from iTunes U or the Internet Archive. Description: In this lecture, the professor talked about spin one-half states and operators, properties of Pauli matrices and index notation, spin states in arbitrary direction, etc. The following content is provided under a Creative Commons license.

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Earlier, we showed that both integer and half integer angular momentum could satisfy the commutation relations for angular momentum operators but that there is no single valued functional representation for the half integer type. Some particles, like electrons, neutrinos, and quarks have half integer internal angular momentum, also called spin.