If you get a beam of light to hit a mirror , and there was a parallel mirror next to it, would the light just?

Question

endlessly jump back and forth?

Answer 1

Theoratically , yes.

Answer 2

that situation is called an optical cavity.  Ideally, only multiples of the wavelengths of light that fit exactly in the distance between the mirrors would exist in the cavity, since the non integer multiples would interfere and cancel out.    so ideally you get only a few wavelengths in the cavity (called cavity modes), and they depend on the size of the cavity.  

in practice, there is always loss.  not completely reflective mirrors, diffraction of the light etc.   and since the lifetime for light in the cavity is finite, you get a spread of wavelengths around the resonant frequencies

the physics is much the same as

http://www.powerset.com/explore/semhtml/...

which gives a good example of the input-output you can expect

Answer 3

assuming incident ray strikes perpendicularly and no loss of energy, the ray will bounce eternally

but since thats probably not the case (no loss of energy), the ray will eventually die off, probably not noticable to the eye.

how much brighter or duller the ray appears wrt incident ray depends on several factors...but u dint ask that...

Answer 4

Depends on the angle of the incident light. If you don't shine it perpendicular to the mirror then the light will propagate like a pinball back and forth until eventually it leaves out the side of your parallel mirror aparatus.

If you shine the beam perfectly perpendicular to your perfectly parralel mirrors then i'm not quite sure what will happen. I guess that tiny imperfections in the mirror will cause the beam to eventually disperse in all directions. Otherwise, if the mirrors dampen the energy in the photons then, the photons will of course not slow down, but change their wave length which will mean the mirror will not be able to reflect them and they will pass straight through or be completely absorbed.

Also, quantum effects and the Heisenberg's uncertantity principle eventually cause even a perfect setup to disperse a light beam or make it tunnel through the mirror, so the beam will never bounce forever between the two mirrors.

We can even conceive of more elaborate problems, such as gravity waves that will slightly bend the photon paths eventually dispersing the beam.

Answer 5

i think the beam would hit the first one, hit the second then hit something else.

but i don't know, go try it. NOW!

:)