BLACK HOLES

Near a black hole, strange things happen in space and time. Black holes are probably the strangest places we know of in the universe.

A river provides a good analogy for what happens to space and time as you get closer and closer to a black hole. Now at first, the water in the river flows pretty slowly. Let’s imagine that it’s flowing at three kilometres per hour, and you can swim at four kilometres per hour. So, you can swim faster than the flow and can easily escape. But as you go further and further downstream towards the waterfall, the river flows faster and faster.

Imagine that you decide to jump into the river just there, on the edge of the waterfall. The water is flowing much faster than you can swim. So, no matter how hard you try, you will not be able to swim back upstream. You will be carried to the edge and you will vanish over the falls.

It’s the same when you are close to a black hole because space flows faster and faster towards the black hole. Light itself, travelling at 300,000 kilometres per second, is not going fast enough to escape the flow, and it falls into the black hole, too.

As you fall into a black hole, if you were going feet first, your feet would be accelerating faster than your head, so you would be stretched, and you would be quite literally made into a spaghetti.

Now, nobody knows what happens when you get into the centre of a black hole. Our best theory of space and time, Einstein’s Theory of General Relativity, says that at the centre of a black hole our understanding of the universe and laws of physics stops. That place is called ‘gravitational singularity’.