We Have No Idea: A Guide to the Unknown Universe

by Jorge Cham

General relativity tells us that at the heart of a black hole there exists a singularity, a point where matter is so dense that the gravitational field becomes infinite. This would be a (literally) mind-bending experience because space-time would distort you beyond any intuitive understanding. General relativity has no problem with such a thing existing, but quantum mechanics disagrees. According to the principles of quantum mechanics, it’s impossible to isolate anything exactly to a single point (like a singularity) because there is always some uncertainty. So one of the two theories has to break down in this situation. If we knew what was actually happening inside a black hole, we would have some very important clues about how quantum mechanics and gravity play together. Unfortunately, the prospects for visiting a black hole, surviving it, doing the experiments, escaping the inescapable gravitational field, and returning to Earth with the results seem daunting at this point.