Explaining Hawking Radiation & Its Effect on Black Hole Mass

• acesuv
In summary: Hawking radiation is the name given to the radiation that comes out of a black hole due to this process of virtual particles being created near the horizon, one of them falling in, and the other escaping to infinity.In summary, Hawking radiation is a process in which virtual particles are created near the horizon of a black hole, one of them falls in while the other escapes to infinity as Hawking radiation. This results in the black hole losing a little bit of mass, as the negative energy particle falling in transfers its energy to the positive energy particle that escapes. The particle that falls in can be either a particle or an antiparticle, and it is not necessarily the antiparticle of the one that
acesuv
From what I understand, Hawking radiation results when one virtual particle (of the pair) falls into the black hole while the other escapes...

See I understand why the virtual particles don't come back together - because one is created beyond the horizon while the other is not.

But how does this process make the black hole LOSE mass? it seems like a particle is flying into the black hole increasing its mass. only thing i can think of is that the particle which flies into the black hole is anti-matter and therefore cancels out a particle of matter inside the black hole... and then my question becomes why does a black hole prefer to eat anti-matter as opposed to the normal-matter particle?

also a side question: are virtual particles simply opposite charges? i see how it makes sense mathematically that (+1) + (-1) = 0... but i don't understand why charge is what mathematically defines the particle... i am under the impression that virtual particles are anti-matter and normal-matter, so that they = 0 which makes more sense to me because the term "anti-matter" sort of implies something intrinsic about the substance that makes it "negative". so yeah. charges? no?

thanks,
Jordan

ps: have fun deciphering my layman jargon

acesuv said:
From what I understand, Hawking radiation results when one virtual particle (of the pair) falls into the black hole while the other escapes...

It's worth noting that this picture is heuristic and doesn't really match how Hawking radiation is derived mathematically; see, for example, the comments here:

http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/hawking.html

acesuv said:
I understand why the virtual particles don't come back together - because one is created beyond the horizon while the other is not.

That's not quite correct. The particles are created at the same place, just outside the horizon; but one falls in while the other escapes to infinity. The one that escapes to infinity is the one we see as Hawking radiation.

acesuv said:
But how does this process make the black hole LOSE mass?

Because the combined energy of the pair of virtual particles is zero; they aren't real particles, they're just fluctuations in the underlying quantum field due to the uncertainty principle. So one of the pair will have positive energy and one will have negative energy. If the one with negative energy falls through the horizon before the particles re-unite, then the hole loses a little bit of mass because a negative energy particle fell into it; and the particle with positive energy becomes a real particle and escapes to infinity as Hawking radiation. Effectively, this process transfers a little bit of the hole's mass to the Hawking radiation particle that flies away.

acesuv said:
only thing i can think of is that the particle which flies into the black hole is anti-matter and therefore cancels out a particle of matter inside the black hole

No, this isn't correct; the particle which falls through the horizon can be either a particle or an antiparticle (a pair of virtual particles always consists of a particle and its corresponding antiparticle, but either one can fall into the hole). The key thing is that the particle that falls in has negative energy. (Note that if the positive energy particle of the pair falls in, no Hawking radiation can be emitted; what will happen in that case is that the negative energy particle will end up falling in too, and re-uniting with the other one beneath the horizon, resulting in no net change to the hole's mass.)

acesuv said:
are virtual particles simply opposite charges?

Antiparticles have opposite charges to particles, yes; but just having opposite charge isn't enough to make one particle the antiparticle of another. All the other particle properties have to be the same: for example, an anti-electron (a positron) has opposite charge to an electron, but it also has exactly the same mass, spin, etc. Whereas a proton, for example, also has opposite charge to an electron, but it has a very different mass, so it isn't the antiparticle to the electron.

acesuv said:
i don't understand why charge is what mathematically defines the particle

It doesn't, not by itself; only the entire set of particle properties (charge, mass, and spin are the key ones, but there are others as well) defines the particle.

acesuv said:
i am under the impression that virtual particles are anti-matter and normal-matter

A pair of virtual particles always consists of a particle and its corresponding antiparticle, as I said above. (Which one we call "normal matter" and which one we call "antimatter" is really an arbitrary choice; there's nothing intrinsic to the particles themselves that makes one "normal" and the other "anti". The particles we call "normal matter" are just the ones we and all the stuff around us happen to be made of.)

1. What is Hawking radiation and how does it affect black holes?

Hawking radiation is a type of radiation that is predicted to be emitted by black holes. It is named after physicist Stephen Hawking, who first theorized its existence. Black holes are thought to emit this radiation due to quantum effects near the event horizon, causing them to slowly lose mass over time.

2. How does Hawking radiation impact the size of a black hole?

Hawking radiation causes black holes to lose mass, which in turn decreases their size. This process is very slow and has a minimal impact on the overall size of a black hole, as it would take an extremely long time for a black hole to significantly shrink due to Hawking radiation.

3. Why is Hawking radiation important in understanding black holes?

Hawking radiation plays a crucial role in understanding the behavior and properties of black holes. It is one of the few ways we can observe and study black holes, as they are invisible due to their strong gravitational pull. Additionally, Hawking radiation provides insight into the connection between quantum mechanics and gravity.

4. Can Hawking radiation cause black holes to disappear completely?

While Hawking radiation does cause black holes to slowly lose mass, it is highly unlikely that a black hole will completely disappear due to this process. This is because the rate of mass loss is extremely small, and it would take an extremely long time for a black hole to completely evaporate.

5. Does the rate of Hawking radiation emission vary for different types of black holes?

Yes, the rate of Hawking radiation emission depends on the size and properties of the black hole. Smaller black holes emit more radiation than larger ones, and the rate of emission also increases as the black hole's mass decreases. Additionally, the rate of emission is affected by the black hole's spin and charge.

• Special and General Relativity
Replies
4
Views
610
• Special and General Relativity
Replies
11
Views
907
• Special and General Relativity
Replies
8
Views
1K
• Special and General Relativity
Replies
4
Views
1K
• Special and General Relativity
Replies
12
Views
3K
• Special and General Relativity
Replies
16
Views
420
• Special and General Relativity
Replies
1
Views
631
• Special and General Relativity
Replies
12
Views
2K
• Special and General Relativity
Replies
6
Views
2K
• Special and General Relativity
Replies
10
Views
644