Sean Carroll

Because what happens is when the observer measures the electron, let's say, let's say, forget about the proton, okay?

Let's say you have an electron that's in a superposition of,

box A and box B. So there's no such thing as where the electron really is.

You can solve the equations for what happens when an observer measures the position of the electron.

And what you get is a superposition of the combined system of electron and observer.

No one disagrees with this, like the solving the equations is not something that you have optionality about, okay?

The equations are what the equations say.

So if you solve the Schrodinger equation, when you measure the position of the electron, the wave function of the universe turns into a quantum superposition of the electron was in box A and the observer measured it in box A, plus the electron is in box B and the observer measured it in box B.

People like Bohr and Heisenberg didn't want to put up with that.

They didn't want to accept that.

And to be fair, they had a little bit of experience on their side, right?

No experimenter has ever felt like they were in a superposition, like that they had both measured the spin up and the spin down of some spinning particle.

You always seem to get a definite outcome.

And Everett's genius philosophical jujitsu move was to say the problem is not that you need to change the equations to add in this wave function collapse and whatever.

The problem is you have to think carefully about identifying yourself in the wave function of the universe.

And he said you should treat those two different parts of the wave function.

One says the electron is in box A and the observer saw it in box A.

The other says the electron's in box B and the observer saw it in box B. You should treat that as separate worlds.

You, the observer, are not the superposition of both of them.

You are one or the other.