# Logical positivism and black hole interiors

A black hole exists. Eventually, it will completely evaporate away.

Alice falls into the hole. Imagine you are Alice. According to logical positivism, the interior of the black hole exists. But you will die at the singularity. You can't measure anything after you're dead, so any event outside after the black hole has vanished doesn't exist.

Bob stays outside the hole. Imagine you are Bob. The interior doesn't exist.

Enter Quentin. Right now, he holds a qubit in the state ${1\over\sqrt 2} (|0\rangle + |1\rangle)$. He will measure the value of the qubit shortly in the future. If 0, he will jump into the hole. If 1, he will stay out forever. Imagine you are Quentin. Right now, does the interior exist?

Curiouser and curiouser.

• If you believe in black hole evaporation, it's possible to escape the interior of the black hole--a shrinking horizon is transversible. – Jerry Schirmer May 13 '11 at 17:27
• Define an observable for "does the interior exist". – dmckee --- ex-moderator kitten May 13 '11 at 17:31
• Why doesn't the interior exist for an outside observer? I don't see how that follows from logical positivism + GR? – Raskolnikov May 16 '11 at 8:14