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What happens when you place two mirrors facing each other? Is it possible to have an infinite amount of reflections?

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Related: physics.stackexchange.com/q/13500/2451 and links therein. –  Qmechanic Sep 29 '13 at 15:40
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up vote 12 down vote accepted

This question reminds me of Zeno's paradoxes.

It is assumed that the two mirror surfaces are absolutely parallel.

In classical physics the electromagnetic waves that create the reflections are uniform and the energy loss due to the reflection ( depending on the material of the glass) will be what will make the reflections fainter and fainter , but the process is continuous and the limit will be a limit in luminosity. In principle a totally reflecting material would have no limit, going to infinite reflections as time goes to infinity. {corrected from original statement that the wavefronts are instantaneous: Maxwells equations obey special relativity i.e. the velocity c of light is finite}

Reality is quantum mechanical and also special relativity dependent.

With special relativity in the problem it will take time to reach the next reflection, so even for a total reflector infinity will also be reached only at infinite time, during observation, though there will be an enormous number of reflections.

Quantum mechanically there can not be a totally reflecting mirror, even in a thought problem. There will always be a probability of absorption and thus a termination of the wavefront eventually, the images getting less and less defined until they become individual photons and finally totally absorbed .

Since quantum mechanics reigns, in reality no, there will not be an infinite amount of reflections.

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Thank you for providing a concise answer! And for including the quantum mechanics portion. :) –  МикроПингвин Feb 27 '13 at 5:02
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protected by Qmechanic Dec 1 '13 at 10:29

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