What would happen if you were travelling through space and you inadvertently end up falling into a black hole? For one thing, you would definitely die. But before this, and up to the point of death, several other things would happen, too.
Toby Wiseman, a theoretical physicists from Imperial College London, explained what would happen to a person in a black hole. "We'd be catastrophically crushed," he said.
"A black hole is a region where space and time have been so distorted that actually the space inside we would expect would get smaller and smaller and eventually and inevitably, we'd be crushed to zero size.
In fact the very last instant physicists don't really understand because nothing can be zero size because quantum mechanics tells you nothing can be exactly zero size."
The speed of this crushing, however, would very much depend on the size of the black hole, he said. For example, a star the same size of our Sun would crush a human in a microsecond (one millionth of a second), so you probably would not feel or see anything.
However, in a black hole from a bigger star, things would take a little longer. "There are very extreme black holes at the centres of galaxies that are many, many millions of times the mass of the Sun – for those, you could last a minute," Wiseman said.
"The biggest ones, you could last a few hours. You'd actually have some time to contemplate probably the most amazing show you would see – although you can't tell anyone about it."
Resistance would be futile. "The whole point of a black hole and an event horizon is that the point of no return – so it's the point of no return," he said. Indeed, even light cannot escape a black hole. Because nothing can travel faster than the speed of light, there would be no point trying to send an SOS signal.
"There's an inevitable time at which you're crushed but how you perceive the time to pass, how quickly, depends on your motion. Einstein says the more you try to accelerate – struggling – the shorter you will perceive that time. So if we were to fall into a black hole, the best thing we could do is to turn off all our rocket engines and not move. That will maximise the time we have."
We – the person falling into the black hole – would not see anything special as we passed through the event horizon, Wiseman said. However, those observing our demise would be able to watch it in slow motion.
"They would actually see our time slow down as we got towards the event horizon. So they would never actually see us pass through the event horizon. They would see us slow down as we approach it and time would slow and slow and slow until we were almost frozen at the event horizon."
After that we would become invisible, and would never be seen again.