Can a photon be length contracted?

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Offline jeffreyH

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Can a photon be length contracted?
« on: 04/11/2015 22:15:05 »
Can the concept of length contraction be applied to photons? If not then why not?
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Offline alancalverd

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Re: Can a photon be length contracted?
« Reply #1 on: 04/11/2015 22:31:04 »
If an object has no existence at rest, it cannot contract from its rest length.
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Offline jeffreyH

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Re: Can a photon be length contracted?
« Reply #2 on: 04/11/2015 22:35:07 »
That's a very good point.
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Offline evan_au

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Re: Can a photon be length contracted?
« Reply #3 on: 05/11/2015 01:44:05 »
Quote from: jeffreyH
Can the concept of length contraction be applied to photons?

Yes. This works with photons (light) as well as phonons (sound).

But it is a Doppler contraction of the wavelength (or it's relativistic equivalent at very high relative velocities between source and receiver).

Unlike relativity, you can also get wavelength expansion, if the source is moving away from you.

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Offline PmbPhy

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Re: Can a photon be length contracted?
« Reply #4 on: 05/11/2015 13:53:14 »
Quote from: jeffreyH
Can the concept of length contraction be applied to photons? If not then why not?
In addition to the above comments you should also take note that no elementary particle that has a non-zero proper mass undergoes Lorentz contraction because it has no dimensions because its radius is zero and L/gamma = L for all point particles having non-zero proper mass.

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Offline Bill S

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Re: Can a photon be length contracted?
« Reply #5 on: 06/11/2015 21:34:08 »
Quote from: evan_au
This works with photons (light) as well as phonons (sound).

My understanding is that phonons are excitations in (for example) a crystal lattice, and that only very long wavelength phonons are associated with sound.  Have I got that right? 
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