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Black Hole Explored - Radiowaves and Thermal Properties

Updated on August 12, 2010

Your question - If the gravity in black holes is so intense that even light cannot escape, then how are x‑rays and radiowaves coming out from there?


My answer - X-rays and radiowaves are not actually emitted from the black hole. At the event horizon, i.e., the outermost boundary of the black hole, matter is constantly pulled into the black hole. Atoms break into their constituent neutrons and electrons and and radiation is emitted which apparently seems to be coming from within the blackhole, but is actually due to falling of disintegrated atoms in the blackhole.


It is assumed that even black holes have thermal properties and apart from that, it is said that when any matter is pulled into a black hole, its atomic structure breaks down, thus emitting a lot of radiation, and this happens outside the black hole, i.e., outside the event horizon. But I agree with you in as much as when everything that comes in the vicinity of a black hole gets sucked into it, then how come these radiations do not get sucked when they are emitting out of a gas/matter which is already being sucked into the black hole or is it the remnant of all that gets sucked into the black hole? It is getting really interesting, isn’t it? Read below for the answer of this.


X-rays and radiowave emissions from black holes

The emissions that are apparently coming from a black hole are actually generated from the empty space around the black hole. Empty space is not entirely "empty". If it were empty then the gravitational and electromagnetic fields will have to be absolute zero, which is not the case. It is assumed that the empty space is filled with particle-antiparticle pairs, which constantly combine to annihilate. The difference between antiparticles and particles lies in the energy possessed. As energy cannot be created out of nothing, theoretically these particle/antiparticle pairs will have a total energy value of zero, so in any instant in which both co-exist, one particle will have positive energy and the other will have negative energy. But again, all real particles can have only positive energy, so the particle with negative energy will be a virtual particle and essentially very short-lived. Due to this instability, this virtual particle will tend to combine with its partner and annihilate. However, if this virtual particle, with negative energy, is in the vicinity of a massive body, its apparent energy will decrease further, because energy is required to lift itself from the gravitational pull of the massive body (here, the black hole). Similarly, for a real particle with positive energy close to a black hole, the apparent energy will be lower because of the high gravitational pull of the black hole. This can effect in the energy of the real particle to also become negative. In effect, then any of these particles real/virtual will be overcome by the gravitational pull of the black hole and fall in it. What happens effectively is, if the virtual particle falls in the black hole and has negative energy, so does the real particle falling in the black hole has negative energy. No longer does the virtual particle need to annihilate with its partner, and it will essentially fall into the black hole. But the real particle of this pair, may still have enough positive energy and get deflected away form the black hole causing emissions.


Also, the erstwhile real particle may lose energy and escape as an anti-particle and will appear as coming from within the black hole.


Now about the thermal properties

As the virtual particle falls in the black hole, it can be similar to a real particle with negative energy, and can be deemed as a real particle, because it will no longer tend to annihilate. If the black hole is small, the virtual particle with negative energy has to travel less distance before it becomes a real particle. The more virtual particles falling in the black hole results in more real particles with positive energy being emitted. The more the energy emitted, the more is the apparent temperature of the black hole. Effectively, again since energy can neither be created, nor destroyed. The amount of positive energy that is being emitted will have an amount of negative energy flowing into the black hole.

But we know from E=mc^2 that, if the energy flowing into the black hole is negative, the mass will also become negative, as the mass and energy are proportional. In effect, the more the emission, the more the loss of mass of a black hole, the more the event horizon shrinks; and the smaller it gets, the higher will be the apparent energy emission from the black hole.


So I hope this answers your question now. Any doubts, let me know through the comment section.


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    • london_guide profile image

      london_guide 7 years ago from Birmingham, West Midlands, UK

      Yes you are very true DANIEL. Thanks for the review of this hub.

    • Daniel V. profile image

      Daniel V. 7 years ago from Romania

      This is the Stephen Hawking's black holes theory, which he beautifully described in his bestseller "A brief history of time", stating that black holes are not that black :) I'm an astronomy enthusiast, but as far as I know, Hawking's theory is not yet verified and black holes still can't be detected, we can only observe the effect of their presence (gravitational lenses, the speed of objects in their vecinity, etc).

    • london_guide profile image

      london_guide 8 years ago from Birmingham, West Midlands, UK

      Thanks a lot for your motivating comment Paradise7.

    • Paradise7 profile image

      Paradise7 8 years ago from Upstate New York

      Thank you, london guide. This complements some other information I've found about black holes and Stephen Hawking's thermal radiation. It's all very fascinating to me, though I only understand the science behind in terms of the concepts and not the math.

    • london_guide profile image

      london_guide 8 years ago from Birmingham, West Midlands, UK

      Thanks a lot for taking time and reading my hub. I will do more.

    • wrenfrost56 profile image

      wrenfrost56 8 years ago from U.K.

      I really enjoyed reading this, I may have to come back and re-read as I didn't fully digest it all, this time round. Thanks for shareing looking forward to reading more of your work.

    • london_guide profile image

      london_guide 8 years ago from Birmingham, West Midlands, UK

      Lets wait and see which theory gets highest significance. Time is the true teller. Thanks aka-dj, shrikrishna, and soni2006 for your valuable inputs.

    • soni2006 profile image

      Rajinder Soni 8 years ago from New Delhi, India

      Yes, I also agree with the STRING theory which is the latest one and also I agree that if it proves to be true, all the rest of the theories will lose their significance.

    • shrikrishna profile image

      shrikrishna 8 years ago

      good luck for future ,

      i am also interested in such studies ,

      but my subjest is now changed , due to some tragedies ,

      thank you ,

      wish you to your success to both london_guide & aka-dj

    • aka-dj profile image

      aka-dj 8 years ago from Australia

      Particle/antiparticle, matter antimatter, visible and dark matter. How much of this stuff is REAL and how much of it resides in the minds of "theorists"?

      The latest theory is "string theory", which, if it is THE real answer, will (for allintents and purposes) eliminate all "particle" theories. They are supposedly tiny strands of energy, vibrating at some frequency, and combibing to give rise to (physical) matter. All to deep for me.

      And to add to the complexity, all this (everything) came into existance, when? and how? Never mind WHY? I love the concepts, because to me, they re-inforce the Glory of the Creator. :)