Understanding Hawking Radiation: Energy Subtracted from Black Holes

[jaydnul]

Something I don't understand is how the energy is subtracted from the black hole. So let's say one pair of virtual particles pop up on the event horizon, the particle goes in, the antiparticle goes out. Then let's say that a second pair does the opposite.

My first question is why is the antiparticle from the first pair colliding with the particle from the second pair any different than colliding with its original partner? Has it just had enough time to become a real particle and therefore emits a photon to conserve energy?

If so, wouldn't the two particles colliding inside the event horizon give off light as well? How is the energy removed from the black hole?

 

[phinds]

I find this very weird myself. The standard "explanation" I have heard several times on this forum is that it doesn't matter which particle falls in, it automatically has negative energy and thus reduces the mass of the black hole.

More significantly, the whole issue of "virtual particles" as the mechanism for Hawking Radiation is bogus. Hawking said that this "particle pair" thing is JUST an analogy that was the closest he could come to describing in English something that really can only be described in the math.

As to another part of your post, anything that happens inside the event horizon is irrelevant to the rest of the universe and does not cause any loss of mass to the black hole.

 

[jaydnul]

But what is the physical process. What does a particle with negative energy actually do to the black hole (other than just saying it takes away energy)?

 

[phinds]

But what is the physical process. What does a particle with negative energy actually do to the black hole (other than just saying it takes away energy)?

Taking away energy is equivalent to taking away mass and that is what Hawking Radiation IS ... the removal of mass from a BH.

EDIT: I think I stated that a bit awkwardly. Taking away mass from a BH is the EFFECT of HR, not quite "what it is" as I said originally).

 

[pmacias]

I can understand your confusion about the concept of Hawking radiation and how energy is subtracted from black holes. Let me try to clarify this for you.

Hawking radiation is a theoretical process proposed by physicist Stephen Hawking in the 1970s. It suggests that black holes, which are known for their immense gravitational pull, also have a temperature and emit particles, called Hawking radiation. This process is possible due to the quantum effects near the event horizon of a black hole.

Now, to address your first question, the antiparticle from the first pair colliding with the particle from the second pair is different from colliding with its original partner because of the time factor. As you correctly mentioned, the antiparticle has enough time to become a real particle before colliding with the particle from the second pair. This conversion of virtual particles into real particles is possible due to the strong gravitational pull near the event horizon. This results in the emission of a photon, which carries away energy from the black hole.

To answer your second question, yes, the two particles colliding inside the event horizon would also give off light. However, this light would be trapped inside the black hole and would not be able to escape its immense gravitational pull. So, we cannot observe this light from outside the black hole.

Finally, to understand how energy is removed from the black hole, we need to look at the bigger picture. As particles are continuously being emitted from the black hole, it loses mass and therefore, energy. This energy is conserved through the emission of Hawking radiation, which carries away energy from the black hole. Over time, this results in the black hole losing mass and eventually evaporating completely.

I hope this explanation helps you understand the concept of Hawking radiation and how energy is subtracted from black holes. It is a complex and fascinating phenomenon that is still being studied and researched by scientists.