Question: what happens if you enter a black hole

Claire Greenwell answered on 8 Mar 2019:

As you get closer to a black hole, you start to feel something called “tidal forces” – this the gravity of the black hole pulling differently on your head and feet (assuming you’re falling in feet first!). We can see this in much less massive objects – for example, the Earth’s gravity is pulling more on the near side of the moon than it is on the far side, because gravity is stronger the closer you are to an object. This is partly why the same face of the moon is always towards us – these tidal forces slowed down the rotation of the moon until it stopped. But a black hole is many times more massive than the Earth – which means the tidal forces are much stronger. You wouldn’t have to get very close before you would notice the difference between your head and feet. You wouldn’t be able to get close enough to be in the black hole without some very unpleasant consequences from the tidal forces.

The other effect you would notice is called “time dilation” – as you get close to a large mass, you would notice the rest of the universe seeming to speed up, and anyone watching from outside would see you slowing down. The gravity of the black hole (and anything massive enough!) slows down time close to it. As you get close to the event horizon of the black hole, this time dilation gets closer and closer to infinitely slow.

Hypothetically, if you could build an advanced spaceship that could get you past both of these problems and into the black hole – I don’t know what it would be like! The physics would get very strange, and I don’t think we’d be able to understand what happens at this point.