Wednesday, 28 June 2017

Who, or What, Killed the Cat?

by Izzy Sambles


During an interesting discussion on quantum physics in a recent physics A level lesson, reference was made to the Schrödinger’s Cat paradox.  Although I had heard of the experiment, I didn’t really understand what it entailed or what it was trying to prove, although I did know that it was famous enough to inspire a Google Doodle, featuring said cat, in memory of Erwin Schrödinger, and be referenced in such high-brow TV programmes as The Big Bang Theory and Doctor Who.  So what’s so special about Schrödinger’s Cat?

In 1935, Erwin Schrödinger designed a hypothetical experiment where a cat would be placed in a sealed box, which contained a radioactive sample, bottle of poison, a hammer and a Geiger counter. The experiment aimed to disprove the quantum mechanics theory entitled the ‘Copenhagen Interpretation’, which puts forth that the cat will be both alive and dead until the box is opened due to the radioactive material’s ability to decay and not decay at the same time within the sealed environment. This is based on the assumption that a particle can exist in all states at once until it is observed, making up the fundamental principle of the ‘Copenhagen interpretation’ of quantum mechanics.

In further detail, the radioactive substance that is used has a 50/50 chance of decaying and being detected by the Geiger counter. It is down to this concept that nobody can be certain if there will be radioactive decay detected, therefore, you don’t know if the hammer will smash the poison glass or not, so you cannot determine the outcome of the cat until you open the box. Therefore the cat would exist in both a living and a dead state until you open the box.


Through his experiment, Schrödinger aimed to illustrate the limits of the Copenhagen Interpretation by applying it to real life situations. In the experiment of the cat in the box, he argued that the cat is actually either living or dead, regardless of whether or not someone is watching, and thus, the concept of the ‘Copenhagen Interpretation’ and the theory of Quantum superposition could not work with large objects as it is impossible for them to be both dead and alive. Therefore, by hypothesing with a cat instead of a particle, Schrödinger makes the theory more tactile in an aim to show the differences in theories produced in quantum mechanics and the flaws of the ‘Copenhagen Interpretation’ and alternate theories such as the ‘many worlds interpretation’ (which argues that, when someone opens the box, a split reality will emerge in which there is one reality where the observer sees a dead cat and in the alternate reality the cat is alive).

So to answer the question posed in my title, in this instance, nobody and no thing killed any cat.


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