Sean Carroll

If I take a electron with a spin and I measure its spin and I measure it to be spin up and then I measure it again, there's no chance if I've done my experiment correctly that it's not gonna be spin up again.

That's what quantum mechanics predicts.

It's not like everything happens.

Certain things happen and certain things don't.

A much more rigorous example is conservation of electric charge.

Conservation of electric charge insists

that possible evolutions for which the electric charge of the universe changes its value do not happen.

Those are possible worlds, conceivable worlds.

They just don't happen according to the evolution governed by the Schrodinger equation.

So it's the Schrodinger equation that is in charge, not just some vague idea that everything out there that possibly happened will happen.

Christian Dobo says, does your one guest, one appearance approach prohibit you from inviting people on the podcast who from inviting people on whose podcast you already made an appearance?

Did this happen before?

And if so, were the topics overlapping?

No, there's no – I don't care about how many times I appear on other people's podcasts or that they appear on mine.

I don't think it happens very often.

It happens sometimes.

You can go back.

When was the last time it happened?

Maybe Daniel Whiteson, maybe?

I don't really remember.