8 Paradoxes Guaranteed To Melt Your Mind

5. Schrödinger's Cat

Schrödinger's cat was a theoretical* thought experiment dreamt up by by physicistErwin Schrödinger in 1935.

In the experiment, a cat is placed in a steel box for an hour with a vial of poison, a piece of radioactive material and a Geiger counter. When the radioactive material decays, the poison is released and kills the cat but, as radioactive decay is a random, subatomic event, there is no way to know whether this has happened without looking and the event can only be described in terms of probability.

However, rather than answering the question "Is the cat alive or dead?" with a callous shrug, due to the nature of quantum particles, you have to answer with "It's both, neither and everything in between". This is the paradox ofSchrödinger's cat.

The cat is dead and alive in equal parts, because the radioactive atom is decayed and not decayed in equal parts. It is what is known in quantum mechanics as "superposition". It is a principle that a system exists in all states at once until it is observed, at which point the wave function collapses and the state is fixed. It has been argued that the Geiger counter is a form of observation and would collapse it before you opened the box to find a dead kitty, but this is slightly missing the point.

The point is that when quantum behaviour is scaled up to the macroscopic, it creates paradox upon paradox - a cat can't actually be dead and alive at the same time -and yet this is actually how the quantum world behaves.

*No cats were harmed in the making of this thought experiment.