# Freely Floating Observer Crosses Event Horizon

• lavinia
In summary, as an observer approaches the event horizon of a black hole, time appears to slow down due to time dilation. Once the observer crosses the event horizon, they are trapped and cannot escape due to the strong gravitational pull. The size of the event horizon is directly proportional to the mass of the black hole. As the observer crosses the event horizon, their body will experience spaghettification due to the intense gravitational pull. There are differences between crossing the event horizon of a stellar black hole and a supermassive black hole, including weaker tidal forces and a larger event horizon for the latter.
lavinia
Gold Member
Can a freely floating observer do an experiment that tells him when he is crossing the event horizon?

Not a "local" experiment.

## 1. What happens to time for a freely floating observer crossing the event horizon?

As the observer approaches the event horizon, time appears to slow down for them. This is known as time dilation and is a result of the extreme gravitational pull near the event horizon.

## 2. Can a freely floating observer escape the event horizon?

No, once the observer crosses the event horizon, they are trapped and cannot escape. This is due to the strong gravitational pull of the black hole, which makes it impossible for anything, including light, to escape.

## 3. How does the size of the event horizon relate to the mass of the black hole?

The size of the event horizon is directly proportional to the mass of the black hole. The more massive the black hole, the larger its event horizon.

## 4. What happens to the observer's body when they cross the event horizon?

As the observer crosses the event horizon, they will experience a phenomenon known as spaghettification. The intense gravitational pull of the black hole will stretch their body, causing it to become elongated.

## 5. Is there a difference between crossing the event horizon of a stellar black hole and a supermassive black hole?

Yes, there are some differences between crossing the event horizon of a stellar black hole and a supermassive black hole. For example, the tidal forces near the event horizon of a supermassive black hole are much weaker, making the spaghettification effect less severe. Additionally, the size of the event horizon for a supermassive black hole is much larger, allowing objects to cross without being torn apart.

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