Can you see infinity?

A cream and green coloured exhibit table and backboard with the title 'Can you see to infinity?' on it. On the top of the table is a blue glass hole with lights.

The brain's experience in judging the depth of tunnels can be used to create a visual illusion.

How it works

Look into a round hole and see a ‘tunnel’ burrowing deep into the ground, even though the hole is about as deep as a frypan.

Things to try or ask around the exhibit

  • Does the tunnel seems to extend deeper than the tabletop?
  • What is creating the illusion of looking into a tunnel?

Background

This exhibit is made with a row of LEDs sandwiched between the two mirrors. The bottom mirror is a normal mirror, while the mirror at the top is a ‘one-way’ mirror, so you can see through the mirror from your side, but the other side is reflective like a normal mirror.

Light from the LEDs is reflected back and forth between the mirrors, so they create the impression that you’re looking into a tunnel which grows narrower as it grows ‘deeper’. An area in your brain’s visual cortex responds to the perceived depth, based on the way the lights reflect back and forth between the mirrors.

Finding the science in your world

A 'House of Mirrors' at a sideshow hall, or even a public restroom which has mirrors mounted above opposite rows of sinks creates similar effects, where reflections between the mirrors creates an image which looks like long hallways that stretch to infinity.