• Question: What weird and cool effects occur when two gigantic mirrors face each other?

    Asked by dyaskelly to Ben, Clare, Ezzy, Mario, Sam on 12 Mar 2012.
    • Photo: Mario Campanelli

      Mario Campanelli answered on 12 Mar 2012:

      have you ever been to one of those old-fashioned barber shops? you have these nice infinite repetitions of the same image between them. But if you put a candle between the mirrors, how come that the infinite number of light rays is not burning us? Well, the distance that these light paths follow is also increasing at each turn, and overall you have an infinite sum of infinitesimal terms, giving you a finite result. One of the beauties of infinitesimal calculus!

    • Photo: Ben Smart

      Ben Smart answered on 12 Mar 2012:

      Do you mean the Casimir effect? It’s a nice (if tricky) example of quantum physics in a tabletop experiment 🙂
      Another tabletop example of quantum physics is the double-slit experiment where you can show that electrons can be in two places at once:
      http://en.wikipedia.org/wiki/Youngs_slits#Interference_of_individual_particles
      You can fire a single electron at 2 slits, and show that the electron has passed through both slits because it interferes with itself.

    • Photo: Elizabeth Pearson

      Elizabeth Pearson answered on 12 Mar 2012:

      I’ve never heard of either of those! How cool. I used to have one of those old fashioned three sided mirrors when I was younger. You can arrange those so that you can see yourself from all angles and makes doing your hair much easier. There are loads of images and it gets quite weird though because some of the images are reversed and some are the right way round. It’s all to do with the reflections of reflections and the different paths the light rays take.

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