Spin Explained for the "Wikipedia Physicist" - No QM Needed!

[tayyaba aftab]

what is chirality of spin state?

 

[Char. Limit]

Well, chirality usually refers to "handedness" of something, or perhaps a better term, nonsymmetry. So it probably has the same sort of meaning here.

 

[es.no]

what exactly is Earth spin?
is there a quantum effect on the Earth spin?what is exactly causes the Earth spin?

You can think of spin as the intrinsic angular momentum of a particle (rather than say, orbital angular momentum).

E.g. If the Earth is moving around the sun, and rotating, the orbit is the regular angular momentum, while the rotation is the "spin" angular momentum.

This is JUST a tool to help you make the concept a bit more concrete. DON'T take it literally. Particles, as far as we know are point particles and therefore can't really spin like the Earth does. Also, if you take an upper limit for the size of the electron, and try to find out how fast it must "spin" then a "point" at the electron's equator would need to be moving faster than the speed of light. This is no good! So don't think of this analogy in the literal sense.

 

[DrChinese]

what exactly is Earth spin?
is there a quantum effect on the Earth spin?what is exactly causes the Earth spin?

Welcome to PhysicsForums, es.no!

Earth does not spin because of quantum effects. It is considered to spin due to classical effects. When free matter in space coalesces to form a celestial object such as a star or planet, total momentum is conserved. Therefore the object takes on the net momentum of its constituents. Usually, there is a net spin component in addition to other components. That is what we observe.

 

[sah-sah]

hello

my question isn't correlate with Earth spin'''''

can you explain to me:
1- In spectroscopy of atoms, such sodium, is specified that in absence of magnetic field,
Apiece of energy levels split to two component except S level.

Why S level isn’t split?

 

[SpectraCat]

hello

my question isn't correlate with Earth spin'''''

can you explain to me:
1- In spectroscopy of atoms, such sodium, is specified that in absence of magnetic field,
Apiece of energy levels split to two component except S level.

Why S level isn’t split?

A better question is why are the other energy levels split? Recall that the S-term correlates with L=0, whereas the other terms have non-zero L. Do you remember the formula for the degeneracy of a particular l-level? Do you know what the particular form of the interaction of the magnetic field with the atomic states is? If you can answer those last two questions, then you should be able to understand why the S-state is unsplit.

 

[sah-sah]

thank you.
you are right

actually,i don't know what the particular form of the interaction of the magnetic field with the atomic states is.

can you tell me?

A better question is why are the other energy levels split? Recall that the S-term correlates with L=0, whereas the other terms have non-zero L. Do you remember the formula for the degeneracy of a particular l-level? Do you know what the particular form of the interaction of the magnetic field with the atomic states is? If you can answer those last two questions, then you should be able to understand why the S-state is unsplit.