Although it has been a century since the birth of quantum theory, its glory, prosperity and prosperity have passed half a century. But the confusion brought by quantum theory 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. This cat is very poor. She (assuming she is a female cat to arouse more pity) is sealed in a secret room with 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, releasing alpha particles, triggering the electronic switch, the hammer falls, the poison bottle is smashed, and the cyanide gas inside is released, the female cat will die. This cruel device was designed by Schrodinger, so the female cat is called Schrodinger cat. 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 rot in the morning or afternoon-that is, the probability that a female 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 this female 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 determine whether the female cat is dead or alive. At this point, the cat's wave function immediately shrinks from the superposition state to an eigenstate. According to quantum theory, if you don't open the lid and observe, you will never know whether the female cat is dead or alive, and it 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. But there is a big problem: it requires the wave function to collapse suddenly. But there is no formula in physics to describe this collapse. Nevertheless, for the sake of pragmatism, physicists have long accepted Copenhagen's explanation. The price paid is: violation of Schrodinger equation. No wonder Schrodinger has been bitter.
Copenhagen interpretation has long been an "orthodox" and "standard" interpretation. But this neither dead nor alive cat always makes physicists fidget like nightmares. What Glibin wants to tell us in Looking for Schrodinger's Cat is where the Copenhagen interpretation failed and what explanation can replace it.
1957, Everett's "multi-world interpretation" seems to bring good news to people, although no one took it seriously at first because it was so bizarre. Glibin thinks that the multi-world interpretation has many advantages, so it can replace the Copenhagen interpretation. Here is a brief introduction to Everett's multi-world interpretation.
Glibin wrote in the book: "Everett ... pointed out that both cats were real. There is a live cat and a dead cat, but they are in different worlds. The question is not whether the radioactive atom in the box decays, but whether it decays. When we look into the box, the whole world splits into two versions. The two versions are the same in all other respects. The only difference is that in one version, atoms decay and cats die; In another version, the atom has not decayed and the cat is still alive. "
In other words, it says, "The atom decays and the cat dies; The atom has not decayed, and the cat is still alive. " These two worlds will evolve completely independently of each other, just like two parallel worlds. Gribbin obviously appreciated this explanation, so he went on to say, "It sounds like science fiction, but ... it is a simple, self-consistent and logical result based on impeccable mathematical equations and quantum mechanics." "In the quantum multi-world, we choose our own path through participation. In the world we live in, there are no hidden variables, God won't roll the dice, everything is true. " According to Glibin, if Einstein were still alive, he might agree with and greatly praise the theory that "God won't roll the dice without hidden variables".
The advantage of this explanation is that the Schrodinger equation will always hold and the wave function will never collapse, which simplifies the basic theory. Its problem is that the idea is too bizarre, and the price paid is that these parallel worlds are equally real. No wonder some people say, "In the history of science, multi-world interpretation is undoubtedly the most daring and ambitious theory put forward at present."