How fast is "Hawking Radiation?"?

Question

I asked in physics too, but maybe you can explain it just as well or better.

Does Hawking Radiation exceed "C" ?
I don't understand it, and probably never will. How do black holes "evaporate?"

How does anything escape a black hole, if "c" is the speed limit of the universe and the surface gravity of a BH is at or greater than "c"

If you can explain it in ways a high school graduate with a "B +" in regular physics can understand, that would be a bonus.

Answer 1

Hawking radiation travels at "c"

I will elaborate below:



Hawking radiation escapes a black hole when one virtual particle in a virtual particle pair is created inside the event horizon of a BH (where nothing can escape) and one is created outside the horizon (where you can escape if you're moving fast enough).

If the particle pair which pops into existence are not photons, then even the one which is created outside the horizon would most likely not have enough speed to escape, and would be pulled into the BH along with it's partner.

Therefore Hawking Radiation should travel at c





Now, for your question about how black holes evaporate:

BH "evaporation" is sort of a misnomer. Nothing is really evaporating. The black hole just loses mass and becomes smaller.

When one virtual particle is created outside the horizon, it becomes real and just like any other particle in the universe.

However, the law of conservation of energy has to come into play somewhere (you can't just create extra energy out of no where).

So, the other particle, which fell into the BH, takes on a "negative mass/energy" and when the black hole absorbs this particle, it loses mass itself and shrinks.



So, nothing really evaporates. The BH takes on negative mass (which is the equivalent of losing mass) and a particle appears to be emitted close to the horizon as a result. The BH isn't returning mass back to the universe - mass is created as a result of mass loss within the BH.

Answer 2

Hawking radiation is the electromagnetic radiation emitted by a non-reflecting body due to its own heat. No, this radiation does not exceed c, the speed of light.



Quantum field theory says that the electromagnetic field has "quantum jitters", even if no charges are disturbing it. In empty space, the electromagnetic field shimmers and vibrates with vacuum fluctuations; Virtual particles pop in and out of existence, and then immediately annihilate each other.



Two virtual photon pairs pop into existence, one inside the horizon, one outside. The one photon cannot escape the black hole's gravity and it stuck, while the other can escape. These photons are called Hawking Radiation.



As black holes lose energy, due to Hawking radiation, they grow smaller. Eventually they reach the Planck length, in which we have no idea what happens.



If you are really interested in black holes, I am reading an excellent book on the topic. It's called "The Black Hole War", and it is about Leonard Susskind's "battle" with Stephen Hawking about information loss in a black hole. Susskind explains everything you need to know about black holes in non-technical language...and he makes it fun!

Answer 3

Good question, and I suspect there's plenty of physicists who don't get it either...it's not simple stuff. All radiation travels at or near c. At least I've never heard of any--radio waves, hawking, x rays, just plain ol' light--that doesn't. If I recall from a few years ago when I was reading about black holes (reading more about 'em than I am now), it's information that is trapped in the hole. That probably confuses the sit-u-ation more than helps it, but there you are. Light can't get out because light is affected by gravity and a hole has so much mass it loops the photon that tries to escape right back in.

Answer 4

The following sentence is from Wikipedia:



"Vacuum fluctuations cause a particle-antiparticle pair to appear close to the event horizon of a black hole. One of the pair falls into the black hole whilst the other escapes."



This is Hawking radiation. The particles are emitted under the speed of light from the event horizon of the black hole, not from its surface. The phenomenon is also known as black hole evaporation.

Answer 5

Awwww, i admire Hawk and that i actual desire that he does not retire quickly. you think of Farmio might take his place if he did retire? i grew to become into so happy that DJ left the sales area tho and went to radio. once you watch a pastime with Hawk and Stoney calling it, you quite study some thing from the pastime in between each and all of the homerisms that Hawk has a tendency to spew. I appreciate it plenty.

Answer 6

E = MC^2 means matter and energy can be turned into one another and then back again. "Hawkings radiation" is pure energy in the form of X rays. What is happening is the matter in the balck hole is being turned into X-rays, which raidate into space. Electromagnetic radiation travels at the speed of light. Nothing can travel any faster than this and only pure energy can achieve this speed. Einstein realized that as any object which had mass approached the speed of light, the energy needed to accelerate it faster would actually be turned into mass. This would make the object more massive, requiring more energy to accelerate it faster. The object would eventually become infinitly massive and require an infinite amount of energy to accelerate, and it would still not be traveling at the speed of light.



Einstein developed his theory of relativity to explain why the speed of light is always constant, no matter what speed the observer was traveling. Two cars traveling at the same speed are essentially stationary, relative to one another. Einstein liked to do "thought experiments" and imagined that if each were traveling at the speed of light, each driver would see the other speed away at the speed of light.



The theory of relativity is based on the idea that a moving object creates its own time frame. The bizzare outcome of this is that somebody walking past another person sitting on a bench in the park is actually in a separate universe with a different time frame. Each is adjusted according to the speed of light so that either observer will clock light at exactly the same speed, even though one of them is moving. This shift in the time frame is not noticed however, because the speed of light is so great. The difference in timeframe is porportional to one's own velocity deivided by the speed of light. This would make the time shift much smaller than a nanosecond..

Answer 7

Hawking used virtual particles in his paper. Virtual particles do not exist in nature, they are a tool of mathematics. I do not not take Hawking's statement seriously, he has made major blunders in the past.