Janna Levin

There is no expansion inside a gigantic black hole. The expansion of the universe has a domain of domination, the largest scales. The black hole overpowers that expansion locally, on the scale of the interior of the black hole. As do we. We are bound so well by atomic forces that we are not expanding with the expansion of the universe. We expand mostly by eating too much.

If only we knew. Here the predictions of general relativity become unreliable. Like a dying man scrawling in the dirt, relativity is telling us something as it breaks down. The singularity is a clue not a genuine prediction, a clue that some other law of physics takes over at these Planck scales. That theory will predict for us what is on the other side. For now, we can conjecture. Maybe a big bang? The birth of a new universe?

Yes, I love this. Think of a black hole as inducing a rotation of space into time and time into space for an infalling astronaut relative to a space traveller at a safe distance. At the event horizon the rotation is complete. All of the infalling astronaut's time has been rotated away and they appear to freeze at the horizon, time effectively stopped. However, from the astronaut's point of view, time ticks completely normally and she falls across the horizon in short order. Inside the black hole, the rotation overshoots. What the distant space traveller called a spatial direction has become a time direction and the infaller sees the singularity not in the center of a sphere, but in her future as inevitable as the next second is for us. There is no more freedom afforded. The singularity can no more be avoided than the conclusion of this hour.