Where is our universe? The universe is not the kind of thing that has a location. It’s not that we want the worlds to be there it’s just the simplest, most austere way of understanding the data. It’s trying to understand how reality works at a deep level. I feel the same way about the other branches of the wave function. If the universe is infinitely big, and it looks the same everywhere, that guarantees that infinite copies of something exactly like you exist out there. There’s a cutoff to how far we can see, so it could be infinitely big. Look, we know our observable universe looks the same, on average, many billions of light-years away from here. It’s just that they’re in separate, non-interacting worlds. Hugh Everett’s brilliant move was to say that the different parts of the superposition really exist. The superposition consists of the electron being here and you seeing it here, plus the electron being there and you seeing it there, and so on. When you look, you evolve into a combined system of you and the electron in a superposition. So what happens when you, the observer, looks for the electron? The electron starts in a superposition of many possible locations. Many Worlds says, why don’t we just treat you, the observer, as your own quantum mechanical system? You’re made of quantum mechanical particles also.

Its description when no one is looking is different from what you see. This is the fundamental mystery of quantum mechanics.

But when you observe the electron, you see it in one location. There’s no such thing as the position of an electron. Quantum mechanics says that an electron can be in a superposition of all possible locations. The job of physicists and philosophers is to show how, if we live in a world that is just a wave function, then why does it look like there are people and planets and tables and chairs? We don’t have a definite consensus. Our classical description of the world is a higher level, approximate way of talking about the wave function.

Something deeply hidden review