The series The Big Bang Theory, in addition to provoking hilarious comic situations, shows us in a very close way a series of scientific lessons in which it is convenient to stop.
In this excerpt, Sheldon invokes Schrödinger’s paradox. ‘Schrödinger’s cat’ is one of the most famous lessons in quantum physics, illustrating its most characteristic and, in turn, incomprehensible and contradictory quality: in 1935, Erwin Schrödinger tried to explain the interpretation of this characteristic of quantum physics made by Copenhagen: the wave-particle duality, by which it can exist in two states at the same time until it is observed.
Schrödinger’s imaginary cat experiment consists of introducing a cat into a box with a vial of toxic gas inside that could break at any moment. With the box closed, no one can tell if the vial has broken or not. One hour after the introduction of the cat, we must consider that the animal would be, at the same time, alive and dead ; and we can only know its status when we open the box and check it. A cruel experiment!
For more details, Schrödinger’s paradox states one of the properties of radioactive decay: although we are able to know whether an atom is going to decay or not, we cannot predict when it will. At most, we can say that, for example, after an hour, there is a 50% probability that an atom will disintegrate. Now, imagine that we took that atom and designed a device so that, if it disintegrated, a vial filled with poisonous gas ruptured. Next, we box this device together with a live cat. After an hour, we are again unable to tell if the cat is alive or dead. Like the atom, it has a 50% chance of being alive and the same chance of being dead.
According to quantum theory, the cat is literally alive and dead at the same time. Only when you open the box, will it become alive or dead. In other words, what quantum physics tells us is that the cat ‘does not exist’ until we observe it. It is at the moment of opening the box when its existence, which until then was a kind of limbo between living and dead, takes shape.
