Columnist
Cosmic conundrums Discovering how weird black holes are made me want to be a physicist. There is still so much to learn about these strange regions, says Chanda Prescod-Weinstein
IT IS easy to be led astray by the mystery of black holes. As a young person, listening to Stephen Hawking describe what we didn’t understand about them was what convinced me that I needed to become a theoretical physicist. They are so strange.
They have this thing called an event horizon and when you cross it, the properties of space and time seem to reverse. Time might lose all meaning. Space becomes one way, in a sense, since the event horizon is a hard boundary that you can only cross once.
Black holes are unlike anything else in the known universe: points of no return embedded into the very structure of space-time. Plus, they are so massive, but also quite compact. A black hole that has the same mass as the sun would stretch only about 3 kilometres across. There are high streets that would longer than a stellar‐mass black hole.
However, even discussing a black hole in terms of mass raises questions because it isn’t really a material object in the same way the sun is. Rather, it is a shape-shifted piece of space-time that has intense gravitational power, pulling on things as if it were an object made of matter.
A black hole is a region, a place in space-time. It can possibly be produced through the presence of a high density of matter, which would be packed together so tightly that space-time folds in on itself, creating a phenomenon that isn’t actually a hole, but isn’t really a material object either.
On some level, I am speaking in terms of conjecture. No human has ever been inside a black hole. And had someone been inside, there is a decent chance they wouldn’t be back again. That said, some things seem able to emerge from one. Quantum mechanics tells us that perhaps information can leak out of black holes. This idea, known as Hawking radiation, is part of what made him a big name in physics before becoming a global celebrity.
So black holes present us with an interesting conundrum: we can draw conclusions about them using calculations, but they are actually quite hard to investigate.
