A thought experiment is a hypothetical situation about which we think and discuss to prove or disprove a point in a theoretical manner, mostly because in reality the situation would be a lot difficult to achieve in compliance with the conditions we require them to. Schrödinger’s cat is one such thought-experiment that deals in quantum chemistry and was initially posed by Erwin Schrödinger to present a problem with one of the ways that people interpreted the bizarre concepts of quantum mechanics, namely the Copenhagen interpretation.
There are many interpretations of the quantum chemistry, the most famous one of them is the Copenhagen interpretation which tried to explain how the quantum world works. The proponents of this interpretation believe that there are multiple states in which a quantum system can exist. These different states can be superposed or added together and they form another quantum state which is completely acceptable. In turn, you can think of every quantum state as an addition of several other quantum states. Whenever we make an observation about the quantum system, all these states are said to collapse into one particular state which is what we observe. This process is known as superposition collapse.
Schrödinger had a problem with this view of the quantum particles. He devised a thought experiment in which a cat was trapped in a box with a radioactive substance, a Geiger counter and a poison vial. If the radioactive substance would decay and release sub-atomic particles or radiation, the Geiger counter would pick up the radiation, the poison vial would break with the action of a hammer and the cat would die. Till the time of the decay the cat would stay alive. Schrödinger then posed a question: if you open the box, will you find the dead cat or the alive cat?
To bell the Schrödinger’s cat
Schrödinger’s cat thought experiment says that according to Copenhagen interpretation of quantum mechanics, the cat will remain alive as well as dead before someone opens the box and then as soon as the box opens, the cat will take one of the states. This hypothetical situation tried to bring out the absurdity of the interpretation. According to Schrödinger, there cannot be two realities existing simultaneously for the cat because there are no version of realities, and that reality is independent of observation. If cat is the observer of its own situation, then it cannot be in two different states. In order to be alive or dead, does the cat’s fate depend on an external observer who opens the box?
Problem with Copenhagen interpretation
With the Schrödinger’s cat experiment, Schrödinger tried to explain that the Copenhagen interpretation does not define what exactly constitutes an observation or measurement. Does the observation have to be a conscious effort on part of the observer or can an unconscious measurement also cause a superposition collapse? Soon, several new interpretations were put forth in an effort to tackle Schrödinger’s cat and try to resolve the paradox in their own fashion. Schrödinger’s cat continues to be a standard of measurement of correctness for every approach towards quantum mechanics and it is important to understand the relevance of the thought experiment.