Difference between spin and polarisation?

[tozhan]

can someone explain to me the difference between spin and polarisation?? someone told me they were the same thing and now I am getting confussed.


Tom

 

[dextercioby]

It's simple."Polarization" is a classical concept,u meet it when discussing any form of waves:electromagnetic,mechanical (sound waves in solids for example),thermal,gravitational.The concept of "spin" is entirely quantum.In QM it is the ratio for the spin angular momentum and is denoted by "s" and can take only integer and semiinteger values;in QFT is the dimension of the irreductible (for 0 and 1/2)/reductible (for 1,3/2,2,...) representation of the restricted Lorentz group.The connection between the two notions is realized by quantizing each classical wave:the electromagnetic->photon,the gravitational->graviton,the sound waves and the thermal waves in solids->phonon.The particles (quanta) have "spin",while the classical waves have "polarization".The photon has spin +1 and has 2 possible spin states.The electromagnetic wave has 2 possible polarization states.

Daniel.

 

[Graeme Robinson]

my, spin and polarisation are two different physical phenomena that are often confused with each other. Let me explain the difference between the two.

Spin refers to the intrinsic angular momentum of a particle. It is a property that particles possess, just like mass and charge. Spin can be thought of as the particle's "spin" around its own axis. It is quantized, which means it can only take certain values, such as spin up or spin down. Spin plays a crucial role in quantum mechanics and is responsible for many phenomena, such as magnetism.

On the other hand, polarisation refers to the orientation of electric or magnetic fields in a wave. It is a property of waves, not particles. Polarisation can be linear, circular, or elliptical, depending on the orientation of the wave's electric or magnetic field. For example, light can be polarised in different ways, which affects how it interacts with matter.

So, in summary, spin is an intrinsic property of particles, while polarisation is a property of waves. They are two distinct concepts and should not be confused with each other. I hope this helps to clarify the difference between spin and polarisation.