What would you see if you have 2 huge mirrors (you cant look over it or next to it)

You place them with the reflecting side to each other and you look in the mirror from behind one mirror (one way mirror = 1 side glass 1 side mirror, like in a movie when cops are questioning a suspect.)

The mirror would reflect each other endless.

The example could be preformed with a see trough mirror (1 side mirror other side glass) but I don't have one, also I don't have huge mirrors.


Would it make a diffrence if you place a light source and if you dont have a light source?

My guess is that you would always see black because there is nothing to mirror.

Edit important:

There is nothing in the room to reflect on, so it only reflects the mirror, thats what i ment.

  • $\begingroup$ Hint: There is no such thing as a "one-way mirror". But if you have a partially reflective mirror (or just a sheet of glass) and one side is well lit while the other is in darkness, it is much easier for people on the dark side to see things on the bright side than vice versa. $\endgroup$
    – The Photon
    Commented Jan 4, 2014 at 1:43
  • $\begingroup$ Why would it be different than if you were standing between the two mirrors? $\endgroup$
    – Kyle Kanos
    Commented Jan 4, 2014 at 3:41
  • $\begingroup$ youtube.com/watch?v=VvqbjUtt3mM this is what i mean here an example (funny) youtube.com/watch?v=fkHlhiG0h70 but what would happen if the cops, plase a mirror on the other side so it mirrors the mirror where they are standing behind. $\endgroup$ Commented Jan 4, 2014 at 13:06
  • $\begingroup$ Do you mean half-reflecting mirror? If the mirror reflects all light, you cannot see anything behind it. $\endgroup$
    – Anixx
    Commented Jan 13, 2014 at 0:49

3 Answers 3


The name one way mirror is misleading. You can get the one-way effect with a partially reflecting mirror and careful lighting, but there is no such thing that passes light in only one direction. Think about it. In the interrogation room you refer to, the "one way mirror" looks like a mirror from the inside of the room. Obviously it is reflecting at least some light back into the room.

What you would see if you had a interrogation room setup with the usual partially reflecting (and therefore partially passing) glass and a normal fully reflecting mirror on the opposite wall, is a series of repetitions of the scene in the room getting dimmer and dimmer as they appear to be father away.

Let's say for sake of example that the partial mirror reflects 80% of the light and passes 20%, and that the mirror on the opposite wall is a perfect 100% reflecting mirror. You are in the dark observation booth and you can see everything in the interrogation room at 20% brightness. Some light from the subject in the room will reflect off the back mirror and then thru the partial mirror. That will look like another copy of the scene (appropriately flipped in orientation) behind the full mirror. You will also see this scene at 20% brightness. The light that reflects off the partial mirror, then the full mirror, then thru the partial mirror will appear from another virtual room behind the previous, and you will see it with 80% * 20% = 16% brightness.

This phenomena repeats creating a infinite succession of virtual rooms behind the real one. Every second virtual room will be 80% as bright as the previous pair. Eventually the brightess will be so low that it will appear black to you, and the succession of virtual rooms ends in darkness from what you can observe.

  • $\begingroup$ yes but what i want to know is what happens if there is nothing in the room and the only thing you see in the mirror is the reflection of the other mirror, so there are no objects to reflect on. $\endgroup$ Commented Jan 5, 2014 at 13:38
  • 2
    $\begingroup$ @Sven: You'd still see the succession of (empty) rooms, each pair being darker than the previous. Eventually they would get so dark and so far away that the endless string of rooms would appear to vanish into a black spot. $\endgroup$ Commented Jan 5, 2014 at 14:06
  • $\begingroup$ i think i cant explain well, lets start over imagine your outside with the two mirrors and there isnt anything between te mirrors. the mirrors only reflect each other so they dont reflect any objects only itself mirror1 reflects mirror 2 mirror 2 reflects mirror1 $\endgroup$ Commented Jan 5, 2014 at 15:24

Your intuition is correct and you would see a endless number of reflections and re-reflections. Without the light in the middle room (assuming there is little or no light where the observer is placed), the so-called "one-way mirror" (@The Photon is correct in that it's technically just a partially reflective mirror) would seem to be just a regular mirror. You can see this for yourself, and maybe even make one: http://hackaday.com/2013/07/23/building-a-blinky-infinity-mirror/


I understand that you are saying that both the mirrors reflect 100 percent yet somehow you are able to see, anyway if this is possible lets first assume you can see the frame of the mirror from which you are seeing in ghe mirror in front, first of all the mirror would continue to get smaller and smaller, and then finally vanish into a point because you would not be able to resolve it, it would be like a sort of pyramid with its apex waaaay inside the mirror.

Now in your original question what you have is even removed the frame, you will see nothing, not even a single dot, see since all the light is reflecting lets assume it's white light the first reflection would be a big white board, now because of 100% reflection the light will not diminish but a smaller white board will be formed, since there is no difference in brightness you will not be able to see this image ane none of the images that would be formed afterwards, since you will not identify any image it would be like shining into a very bright like, something like looking into floodlights from real close.


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