This cat is very poor. It is sealed in a secret room, which contains food and poison. There is a hammer on the poison bottle. The hammer is controlled by an electronic switch which is controlled by radioactive atoms. If the nucleus decays, it will release alpha particles, trigger the electronic switch, the hammer will fall, the poison bottle will be smashed, the cyanide gas inside will be released, and the cat will die. This cruel device was designed by Schrodinger, so this cat is called Schrodinger's cat.

The proposition of "Schrodinger's cat"

Schrodinger's unlucky cat

Schrodinger published a paper in 1935 "Schrodinger's unlucky cat", entitled "The present situation of quantum mechanics".

In the fifth section, Schrodinger described the cat experiment, which is often regarded as a nightmare: the Copenhagen school said that before the measurement, the state of a particle was fuzzy and was in a mixed superposition state of various possibilities. For example, when radioactive atoms decay is completely random. As long as there is no observation, it will be in the superposition state of decay/non-decay, and only when it is actually measured will a state be randomly selected. So let's put this atom in an opaque box and keep it in this superposition state. Now Schrodinger imagines a precise device with ingenious structure. Every time an atom decays and releases a neutron, it will trigger a series of chain reactions. The final result is to break a poison gas bottle in the box, and there is also a poor cat in the box. The thing is obvious: if the atom decays, the poison gas bottle will be broken and the cat will be poisoned. If atoms don't decay, then cats live well.

Natural reasoning

Schrodinger's Cat

When they are all locked in the box, the atom is in the superposition state of decay/non-decay because we have not observed it. Because of the cat shape of the atomic Schrodinger

The state is uncertain, so the state of the cat is also uncertain. Only when we open the box and have a look, the matter is finally decided: either the cat is lying dead in the box, or it is alive and kicking and meowing. The question is, what was the state of the cat before we opened the box? It seems that the only possibility is that it is in a superposition state like our atom, and the cat is caught in a dead/alive mixture.

A cat died and lived at the same time? In the superposition of neither dead nor alive? This conflicts with common sense too much, and at the same time, it is also a strange talk from a biological point of view. If a live cat comes out of the box, if it can talk, will it describe the strange feeling of dead/alive superposition? I'm afraid it's unlikely. In other words, Schrodinger put forward the concept of cat to solve the grandmother paradox brought by Einstein's theory of relativity, that is, the theory of parallel universe.

Although it has been a century since the birth of quantum theory, its glory, prosperity and prosperity have passed half a century. However, quantum theory once caused the confusion of Schrodinger's cat quantum computer principle.

It still puzzles people today. As Bohr famously said, "Anyone who is not confused when he first hears quantum theory must not understand it." Schrodinger's cat is the representative of many quantum puzzles.

The decay of nuclear is a random event, and physicists can only know the half-life-the time required for semi-decay. If the half-life of a radioactive element is one day, one day later, the element will be half less, and the other day, the remaining half will be half less. However, physicists can't know when it decays, morning or afternoon. Of course, physicists know the probability that it will decay in the morning or afternoon-that is, the probability that a cat will die in the morning or afternoon.

If we don't open the lid of the secret room, according to our daily experience, we can conclude that the cat is either dead or alive. These are her two eigenstates. However, if Schrodinger equation is used to describe Schrodinger cat, it can only be said that she is in a superposition state of life and death. Only by lifting the lid can we know for sure whether the cat is dead or alive. At this point, the cat's wave function immediately shrinks from the superposition state to an eigenstate.

Quantum theory holds that the cat will never know whether it is dead or alive without opening the lid, and she will always be in a state of superposition of half-dead and half-dead. This seriously violates our daily experience. We either die or live. How can we achieve immortality?

Schrodinger sarcastically said: According to the explanation of quantum mechanics, the cat in the box is in a "dead-alive superposition state"-both dead and alive! Wait until you open the box and take a look at the cat before deciding its life and death. (Please pay attention! This is not a discovery, but a decision. One look is fatal! As Prince Hamlet said, "To be dead or alive is really a question." Only when you open the box, the superposition state suddenly ends (in mathematical terms, "collapse"), and Prince Hamlet's hesitation finally ends. We know the exact state of a cat: dead or alive. The advantage of Copenhagen's probability explanation is that there is only one result, which is consistent with what we have observed.