Schrödinger’s cat is one of the most famous physics thought experiments. In this post, I will explain what the thought experiment is, the weird phenomenon it seeks to express and the origins of it.
So lets start with what Schrödinger’s cat really is. Erwin Schrödinger was a fantastic physicist in the 20th century. His influence spread across numerous fields, but he is best known for his work in quantum mechanics, even forming a whole new part, involving waves and which spawned the second most famous physical idea with his name associated with it, Schrödinger’s wave equation. But that isn’t what we are talking about today. Quantum physics is a very strange subject, we have talked about it before so I’m not going to go into much detail, but because of its complexity, there are many ways to interpret it. At Schrödinger’s time, the most popular was something called the Copenhagen interpretation.
Schrödinger found a part of this interpretation very difficult to accept, concerning an idea called superposition. It said that a particle could be in two states at the same time until it is measured. Schrödinger’s cat was Schrödinger’s attempt of showing how this was impossible, through applying it on a macro scale. The experiment involved putting a cat in a box with a geiger counter and a radioactive substance. After an hour, there is a 50/50 chance that the radioactive substance would have emitted a particle. When the geiger counter detects that this has happened, it will break a vial of poison, thus killing the cat. Schrödinger said that, after an hour has passed, using this quantum interpretation, the radioactive substance has both emitted a particle, and not (so far so accurate). As the chain of events would follow, the cat is then both alive and dead.
The main problem that Schrödinger was trying to show here that the idea that something so obviously either one way or the other, could be in this state until we observed it was entirely possible with this interpretation. However, nothing in quantum says that isn’t possible. Superpositions have been proven to exist, the question is of when this state collapses into one outcome. This problem is one that has taxed physicists for decades and is one of the great unanswered questions in physics. Minute Physics did a great video on this:
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