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Old Jul 23rd 2017, 01:37 PM   #1
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Does a photon spin?

Does a photon have zero spin? around any axis? If it has zero spin are we 100% sure or is that uncertainty governed by Heisenbergs's uncertainty principle?
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Old Jul 23rd 2017, 03:21 PM   #2
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Originally Posted by kiwiheretic View Post
Does a photon have zero spin? around any axis? If it has zero spin are we 100% sure or is that uncertainty governed by Heisenbergs's uncertainty principle?
In quantum mechanics the term spin means that a particle has intrinsic angular momentum. The term comes originates from classical mechanics regarding rotating body. There is no axis around which it "rotates" and in fact one can't even speak of such a rotating point particle such as a photon.

There is nothing in physics which is 100% certain since that would imply that we've actually proved something which science is not cable of in general.

Watch this for details
http://www.newenglandphysics.org/com...an_Guth_04.mp4
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Old Jul 24th 2017, 01:55 PM   #3
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Originally Posted by kiwiheretic View Post
Does a photon have zero spin? around any axis? If it has zero spin are we 100% sure or is that uncertainty governed by Heisenbergs's uncertainty principle?
The uncertainty principle always applies in Quantum Mechanics, photons are gauge bosons and as such they follow Bose-Einstein statistics. They have a spin of 1 not zero.
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Old Jul 24th 2017, 02:26 PM   #4
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Originally Posted by NikPerk View Post
The uncertainty principle always applies in Quantum Mechanics, photons are gauge bosons and as such they follow Bose-Einstein statistics. They have a spin of 1 not zero.
So we have 100% certainty that a photon has spin 1 ? So we just have a bit of heisenberg uncertainty about which axis that spin is distributed along but we know it has spin of magnitude 1 ?
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Old Jul 24th 2017, 02:37 PM   #5
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Originally Posted by kiwiheretic View Post
So we have 100% certainty that a photon has spin 1 ? So we just have a bit of heisenberg uncertainty about which axis that spin is distributed along but we know it has spin of magnitude 1 ?
We never have 100% certainty, that was already explained by the other user. Edit: The same for the axis. You are thinking in classical terms, QM is weird
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Old Jul 24th 2017, 03:36 PM   #6
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Originally Posted by NikPerk View Post
We never have 100% certainty, that was already explained by the other user. Edit: The same for the axis. You are thinking in classical terms, QM is weird
I meant "heisenberg certainty", not certainty in the classical philosophical sense :-) I take it that the laws of the universe themselves are not subject to "heisenberg uncertainty". They are either laws or they are not, right? Not just on Tuesdays.
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