# Relativistic effects on photons
**URL:** https://boards.straightdope.com/t/relativistic-effects-on-photons/483786
**Category:** Factual Questions
**Created:** [January 30, 2009, 9:54pm UTC](https://boards.straightdope.com/t/relativistic-effects-on-photons/483786 "2009-01-30T21:54:34Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@Cardinal](https://boards.straightdope.com/u/Cardinal)
#### Post date: [January 30, 2009, 9:54pm UTC](https://boards.straightdope.com/t/relativistic-effects-on-photons/483786/1 "2009-01-30T21:54:34Z")
At this link, [Quantum Weirdness – Part 3 Polarized Light Weirdness | Quantum Weirdness](http://quantumweird.wordpress.com/quantum-weirdness-a-matter-of-relativity-part-3/) there’s a discussion on quantum weirdness and the effect on polarized light.
Is the author saying that the distance between one crystal and the other essentially contracts to 0 because the photon is traveling at the speed of light?
Also, I don’t understand how putting the photon through 2 vertical polarizers even at the same time returns the photon to the original orientation.
Do you have an explanation for an “I’m really more of a chemistry dude” person?
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### Author:  [@The\_Hamster\_King](https://boards.straightdope.com/u/The_Hamster_King)
#### Post date: [January 30, 2009, 10:08pm UTC](https://boards.straightdope.com/t/relativistic-effects-on-photons/483786/2 "2009-01-30T22:08:25Z")
> [@Cardinal](#):
>
> Also, I don’t understand how putting the photon through 2 vertical polarizers even at the same time returns the photon to the original orientation.
Don’t think of the photon as a little marble moving through space. Basically it’s taking ALL possible paths simultaneously. It’s not that it has a 50% chance of taking the top path and a 50% chance of taking the bottom path. It always takes BOTH paths. We just have a 50/50 chance of detecting it on one or the other. So when the second crystal combines the two paths again the photon “mixes” with itself and returns it’s original orientation.
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### Author:  [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)
#### Post date: [January 31, 2009, 1:27am UTC](https://boards.straightdope.com/t/relativistic-effects-on-photons/483786/3 "2009-01-31T01:27:54Z")
> [@](#):
>
> Also, I don’t understand how putting the photon through 2 vertical polarizers even at the same time returns the photon to the original orientation.
What **Pochacco** said. Between the crystals, it’s very analogous to a double slit experiment. The photon is in a superposition of the “top H” and “bottom V” states, but if you don’t interfere with the photon, that superposition corresponds to a photon at 45 degrees after they recombine.
> [@](#):
>
> Is the author saying that the distance between one crystal and the other essentially contracts to 0 because the photon is traveling at the speed of light?
Yes, that’s what he’s saying, and I suppose the “contracts to zero” part is technically true. Mostly, the rest sounds like technobabble to me. I suspect the author doesn’t have real equations to back up his words in the “Relativistic Effects Again” section. Unless someone else can point to actual equations describing the physics in that frame of reference, I wouldn’t worry too much about understanding it.
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [January 31, 2009, 1:55am UTC](https://boards.straightdope.com/t/relativistic-effects-on-photons/483786/4 "2009-01-31T01:55:04Z")
> [@](#):
>
> Unless someone else can point to actual equations describing the physics in that frame of reference, I wouldn’t worry too much about understanding it.
A photon doesn’t have a frame of reference. They are literally timeless objects.
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### Author:  [@kierk](https://boards.straightdope.com/u/kierk)
#### Post date: [January 31, 2009, 6:50am UTC](https://boards.straightdope.com/t/relativistic-effects-on-photons/483786/5 "2009-01-31T06:50:00Z")
to expand on Chronos’ answer I’ll provide a wiki link
[Length contraction and time dilation](http://en.wikipedia.org/wiki/Special_relativity#Time_dilation_and_length_contraction)
the limit of the gamma factor as velocity approaches c is infinite.
putting that into the length and time contractions gives you the odd results that for photons, the measurement of any distance is zero, and the measurement of any time is infinite. Since this is Special Relativity this is only valid when the photon is not accelerating, so works for straight line point to point travel, but invalid within the prisms as the referenced article describes.