Everett's interpretation accepts the quantum equations entirely at face value and says that both cats are real. There is a live cat, and there is a dead cat; but they are located in different worlds. It is not that the radioactive atom inside the box either did or didn't decay, but that it did both. Faced with a decision, the whole world—the universe—split into two versions of itself, identical in all respects except that in one version the atom decayed and the cat died, while in the other the atom did not decay and the cat lived. It sounds like science fiction, but it goes far deeper than any science fiction, and it is based on impeccable mathematical equations, a consistent and logical consequence of taking quantum mechanics literally.
John Gribbin
