Understanding Photon Interference: A Look at Wavelength and Molecule Distance

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tionis
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[Moved from https://www.physicsforums.com/threads/if-a-photon-were-trapped-between-two-perfect-mirrors.880490/ because it's a different question]

edguy99 said:
Dont forget your perspective here. The wavelength of a red photon is 630 nanometers, the distance where you start to see interference between photons. The average distance between molecules is only about 0.1 nanometers, some 6000X smaller.

Hi, ed. Could you explain what you mean by interference between photons? Is there a wavelength smaller than 0.1nm for EM radiation?
 
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tionis said:
Hi, ed. Could you explain what you mean by interference between photons? Is there a wavelength smaller than 0.1nm for EM radiation?

What is interference between photons? - If you shoot a second stream of 630nm photons, you see wave like interference patterns that suggest something periodic of that size. Some photons reinforce other photons and it looks bright. Some photons interfere with other photons and you can't see anything at all.

Smaller size? - sure you can start with a smaller wavelength photon. But smaller wavelength means higher energy. If you get small enough, the photon will have enough energy to blast itself right through the wall.

Also don't forget that you cannot "squeeze" photons to make them smaller. Photons either crash into something where they disappear and transfer their energy to a molecule; or certain crystals can split them in 2, but produce two photons at 1/2 the energy and twice the wavelength (bigger).
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edguy99 said:
What is interference between photons? - If you shoot a second stream of 630nm photons, you see wave like interference patterns that suggest something periodic of that size. Some photons reinforce other photons and it looks bright. Some photons interfere with other photons and you can't see anything at all.
EM waves interfere with each other, not photons.
 
tionis said:
[Moved from https://www.physicsforums.com/threads/if-a-photon-were-trapped-between-two-perfect-mirrors.880490/ because it's a different question]
Hi, ed. Could you explain what you mean by interference between photons? Is there a wavelength smaller than 0.1nm for EM radiation?
X-rays typically have wavelengths in the range of 0.01-10 nm. Gamma rays are usually below 0.01nm, but the distinction between the two is usually given by the source of the radiation, not on the wavelength.