wu :: forums - Print Page


    
      
        wu :: forums
        (http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi)
      

        riddles >> what happened >> You are inside a cubic room
        
(Message started by: alien on Dec 10^th, 2005, 6:07pm)

Title: You are inside a cubic room
Post by alien on Dec 10^th, 2005, 6:07pm

I heard this riddle about 2 years ago, and it goes something like this:

You are standing in the middle of a cubic room made of mirrors. How many reflections do you see if we consider one wall?

Title: Re: You are inside a cubic room
Post by towr on Dec 11^th, 2005, 7:44am

[hide]Depends on how much light there is, and how sharp you can see, and what's the lowest contrast you can distinguish, how much light is actually reflected by the mirrors, etc[/hide]

Title: Re: You are inside a cubic room
Post by alien on Dec 11^th, 2005, 8:04am

You have practically solved the riddle: the intended answer is [hide]that there is no light, so you see nothing.[/hide] ::) But let us suppose that [hide]there is light[/hide] - what do you think how many reflections would you see then, eh?

Title: Re: You are inside a cubic room
Post by towr on Dec 11^th, 2005, 3:11pm

It's hard to say; with a 3% loss of light at reflection, and a visual range of a factor million for light intensity you could potentially see up to a depth of log(1/1000000)/log(0.97)= +/- 453 reflections. Depending on the dimensions of the room, and clear air, clean mirrors, the (virtual) distance shouldn't be a problem (I think vision is sharp enough to see a person up to a few kilometers under optimal conditions).
But these are all guesstimates.

Title: Re: You are inside a cubic room
Post by Grimbal on Dec 12^th, 2005, 1:25am

This is related to the line of sight (http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi?board=riddles_medium;action=display;num=1127325065;start=6#6) problem.
You don't see an infinity of yourself as intuition might suggest. Given the size of your head and the size of the room, you should be able to find an upper bound. But it is 3D here, I don't know how it works out.