how can black holes emit radiations when a black hole is something which absorbs everything?

Answer 1

Psst...it's called Hawking radiation(named after guess who?). Over the billions of years,.black holes will just evaporate.

Answer 2

Exercept from the site :--http://imagine.gsfc.nasa.gov/docs/ask_astro/black_holes.html


As the matter falls into the black hole, and before it enters the event horizon, it turns gravitational potential energy into kinetic energy and so picks up a lot of speed. Some of this energy is then converted into light and other electromagnetic energy. But the most luminous part of black holes are the jets of accelerated matter that are emitted from the polar regions. These are probably generated because of the very strong rotating magnetic field that is usually associated with Black Holes.


There are multiple ways to visualize the generation of Hawking radiation. The first is indeed the separation of virtual matter/antimatter pairs by the intense gravitational force exerted by the black hole and the other is the quantum tunneling of a particle, such as a photon out of the black hole event horizon.

Both cases describe black hole evaporation. The best way to think of why indeed the black hole is losing energy in the matter/antimatter scenario is that particles are actually created at the expense of gravitational energy (which is then related to the properties of space-time). Consider the following example. Say there's a particle moving toward a large mass --the particle feels the gravitational pull of the mass. The gravitational field exerts a potential energy on the particle which in turn is converted to kinetic energy of the moving particle. To conserve total energy the potential energy of the mass gets more negative. Indeed, the mass experiences a loss of potential energy as the particle experiences a gain in kinetic energy. So in the same way, at the black hole event horizon, two virtual particles --say photons --separate due to the gravitational force of the black hole; one adds negative energy as it falls into the black hole, the other (now a real particle) escapes.

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Answer 3

If a black hole could exist it would be a 2 to 3 solar mass entity about 3 km in diameter.
It would have a theoretical surface such that the gravity would be so intense that the escape velocity would be greater than the speed of light.
Nothing could escape, Hawking radiation not withstanding.
Virtual particles are something that has never been observed and may not exist.
A photon of light skimming the surface would not be seen.
A photon leaving the surface would be seen.
The quantum effect mandates that a number of photons in a group must be faster than "C".
these photons landing on the surface tangentially would escape and be visible as a dim glow in white light,so a black hole wouldn't be black at all.

Answer 4

In classical general relativity, a black hole absorbs everything. When you combine general relativity and quantum mechanics in the presence of event horizons (which a black holes have), you get new physics that would not be possible to understand in general relativity only.

This is what Hawking did, and subsequently was able to show that quantum mechanical effects lead to that black holes radiate energy away and will finally completely evaporate away.

It is important to consider results within the theory they are calculated in.

Answer 5

This is very counterintuitive, but it does indeed happen (in theory).

The best way to visualize it is like this... Recall that even the empty vacuum is "boiling" with virtual particle/antiparticle pairs that blink in and out of existence. Now, if such a particle pair appears close enough to the event horizon of the black hole, one of the particles can be absorbed into the black hole, while the other particle escapes!

Answer 6

Yeah, it's called Hawking Radiation and involves a particle decaying into another particle and an antiparticle at the exact edge of the event horizon. If everything works out just right, one of them (either the particle or the antiparticle) will appear inside the event horizon and be trapped. But the other particle may appear outside the event horizon and, if it has sufficient momentum, it can escape.

Doug

Answer 7

It doesnt absorb everything.
black holes slowly throw off and atom here and there.
explaining why is to long read a few of Stephen hawkings books.
As a matter of fact black holes that have nothing around them to consume will eventually dissipate and fad away because of the lose of material
nothing in the universe is for ever except the void.
kind of depressing...

Answer 8

Black hollow does not emit x-rays. even though it does emit debris(Hawking Radiation). those are particle-antiparticle pairs of digital debris, generated close to the form horizon by using capability fluctuations from the vacuum of the black hollow. Randomly, between the particle falls into the black hollow mutually as the different is emitted as Hawking radiation earlier they have an threat to annihilate one yet another. If the particle that falls into the black hollow ensue to be an antiparticle, then its adverse capability will shrink the black (black hollow evaporation). Hawking radiation isn't emitted from the black hollow yet quite from the exterior of it (close to its journey horizon) and those debris are yet to be reported.

Answer 9

I have studied black holes for years!!! A supernova explosion that is big enough can create a black hole. the star remnants circulate around the hole at 1billion degree's. Question solved.

Answer 10

every being whether it be an absorption or expulsion of energy source will generate an opposing conduit of energy, trying to achieve a balance to in turn attempt to be stable, in the case of a black hole, the extreme gravitational force generates energy proportionally to the amount of energy it takes in, since it generates energy that it returns to the intake, the energy source will be self sustaining until the inevitable collapse do to forces we yet to understand