• Orbb
In summary, the conversation discusses the concept of Hawking radiation and its effect on an observer falling into a black hole. It is noted that for a free-falling observer, the time it takes to cross the event horizon is finite, but for an asymptotic observer, it is infinite. However, the time it takes for the black hole to evaporate due to Hawking radiation is finite, meaning the asymptotic observer would see the black hole evaporate before the free-falling observer reaches the event horizon. It is also questioned what the free-falling observer would see in this situation. The conversation concludes with a reference to an article that further explains this concept.

#### Orbb

I have a question concerning black holes and hawking radiation. I hope it is an adequate question and I pose it in the right section.

Consider a free-falling observer 1 approaching the event horizon of a black hole. Evaluating his proper time, one finds that he crosses the event horizon within finite time. For an asymptotic observer 2 however, the time it takes observer 1 to cross the event horizon is infinite. However, the time it takes for the black hole to evaporate due to Hawking radiation is finite. So observer 2 would see the black hole evaporate before observer 1 reaches the event horizon. Is that correct? And what would observer 1 see? The Universe, including the black hole accelerating in time so that the black hole vanishes in radiation before he can reach it?

That answers my question perfectly, thank you very much!

## 1. What is BH infall?

BH infall refers to the process of matter falling into a black hole. As matter gets closer to the event horizon of a black hole, it accelerates and eventually crosses the event horizon, becoming part of the black hole's singularity.

## 2. How does Hawking radiation work?

Hawking radiation is a theoretical process proposed by physicist Stephen Hawking in which black holes emit radiation due to quantum effects near the event horizon. As particles and antiparticles are constantly being created and annihilated near the event horizon, some particles may escape while others fall into the black hole, resulting in a net loss of energy and mass for the black hole.

## 3. Can Hawking radiation cause a black hole to evaporate?

Yes, Hawking radiation can cause a black hole to lose mass and eventually evaporate. However, this process is extremely slow for large black holes, and it would take trillions of years for a black hole the size of our sun to evaporate completely.

## 4. How does BH infall affect Hawking radiation?

BH infall can affect Hawking radiation in a couple of ways. First, as matter falls into a black hole, it can contribute to the black hole's mass, slowing down its evaporation. Second, the mass and rotation of a black hole can alter the quantum effects near the event horizon, potentially changing the rate and spectrum of Hawking radiation emitted.

## 5. Can we observe Hawking radiation?

Currently, we do not have the technology to directly observe Hawking radiation from a black hole. However, scientists are studying the effects of Hawking radiation on the cosmic microwave background radiation, and future experiments may be able to detect this radiation indirectly.