What is Hawking radiation: Definition and 202 Discussions

Hawking radiation is black-body radiation that is predicted to be released by black holes because of quantum effects near the black hole event horizon. It is named after the physicist Stephen Hawking, who developed a theoretical argument for its existence in 1974.The requirement that black holes lose energy into the wider universe, and therefore can "evaporate" and the radiated spectrum are both a result of analysing black hole thermal equilibrium combined with extreme redshifting effects very close to the event horizon, with some consideration of quantum entanglement effects. A pair of virtual waves/particles arises just outside the event horizon due to ordinary quantum effects. Very close to the event horizon, these always manifest as a pair of photons. It may happen that one of these photons passes beyond the event horizon, while the other escapes into the wider universe ("to infinity"). A close analysis shows that the exponential red-shifting effect of extreme gravity very close to the event horizon almost tears the escaping photon apart, and, in addition, very slightly amplifies it. The amplification gives rise to a "partner wave", which carries negative energy and passes through the event horizon, where it remains trapped, reducing the total energy of the black hole. The escaping photon adds an equal amount of positive energy to the wider universe outside the black hole. In this way, no matter or energy ever actually leaves the black hole itself. A conservation law exists for the partner wave, which in theory shows that the emissions comprise an exact black body spectrum, bearing no information about the interior conditions.Hawking radiation reduces the mass and rotational energy of black holes and is therefore also theorized to cause black hole evaporation. Because of this, black holes that do not gain mass through other means are expected to shrink and ultimately vanish. For all except the smallest black holes, this would happen extremely slowly. The radiation temperature is inversely proportional to the black hole's mass, so micro black holes are predicted to be larger emitters of radiation than larger black holes and should dissipate faster.

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  1. C

    The True Nature of Hawking Radiation

    With the theory of Hawking Radiation, people generally say to imagine that the black hole has a temperature, so it must radiate heat. But, this really is not how it is said to work. The means by which the black hole evaporates is not that particles are actually coming out of it, or that it is...
  2. srfriggen

    Hawking Radiation: Mass & Decay Rate

    Posted this on the Astrophysics page but I think it is more appropriate here... Last night in my calculus class I learned about radioactive decay, a nice example using radium. I was taught that the smaller the mass, the slower the rate of decay (or at least that's what I absorbed, I still...
  3. srfriggen

    Hawking Radiation: Rate of Decay & Mass

    Last night in my calculus class I learned about radioactive decay, a nice example using radium. I was taught that the smaller the mass, the slower the rate of decay (or at least that's what I absorbed, I still have to go over my notes again. Or does the rate not change, but the time it takes...
  4. D

    Technical question about Hawking radiation

    I see how it is derived for the BH and in case of Unruh effect. In Unruh effect it is a function of acceleration In case of BH distance to the event horizon plays important role What I can't find, however, how tidal forces should be taken into account. For example, in the universe with DE...
  5. J

    Practical possibility of Hawking radiation?

    i have long been a skeptic of hawking radiation. i would like to explore my concerns, and see what your reaction is. the concept hinges around the idea of a spontaneous particle pair being created somewhere near the EH of a BH. radiation would occur if one of the particles manages to escape...
  6. Ranku

    Exploring the Temperature Differential of Hawking Radiation

    Hawking radiation is supposed to emanate from black holes because black holes have a temperature. A black hole has to be about 3 times the solar mass. A black hole with a few times the mass of the sun would have a temperature of only one ten millionth of a degree above absolute zero. This is...
  7. M

    Why Hawking radiation contains other particles besides photon?

    Hawking radiation is standard thermal spectrum, thermal spectrum means it only can emit photon. why Hawking radiation contains other particles?(electron neutrino neutron proton etc)
  8. J

    More Hawking radiation misinformation

    typical poor science reporting on our national media - this time about HR on msnbc.com: http://www.msnbc.msn.com/id/32781964/ns/technology_and_science-science the article states: "Contrary to popular belief, black holes do not suck up absolutely everything around them. They actually emit a...
  9. C

    Hawking Radiation: How Do Black Holes Emit?

    if light cannot escape a black hole then how do they emit stuff called hawking radiation.
  10. J

    Crossing event horizon and Hawking radiation

    Some thought experiments and questions. I would much appreciate any comments on whether my analyses below are correct. 1. I am falling feet first into a black hole. An external observer will never see me fall past the event horizon. However, in my frame of reference I will fall past it in...
  11. J

    2 Q's - hawking radiation and inflationary universe

    Q1 - hawking radiation hinges around spontaneous particle pair creation near the EH of a BH. the spontaneous pair can only exist for less than the Planck time. how can either of the particle pair travel a far enough distance in that ridiculously small amount of time to actually cross the EH...
  12. S

    How is Hawking Radiation Related to a Black Hole's Mass and Time of Dissipation?

    How exactly is the amount of Hawking radiation emitted by a black hole related to it's mass/Schwarzschild radius/etc? Is there a formula relating the two for instance? (I'm trying to calculate the time it would take for one of the LHC black holes that will supposedly destroy the Earth - ad...
  13. M

    Hawking radiation: why only one way?

    I'm trying to understand how Hawking radiation works but, as usual, most explanations are oversimplified so they don't appear to make sense. If I understood correctly, pairs of particles and antiparticles pop into existence everywhere in the universe all the time, and usually annihilate each...
  14. O

    Black Holes and Hawking Radiation: The Time Dilation Paradox

    I have a question concerning black holes and hawking radiation. I hope it is an adequate question and I pose it in the right section. Consider a free-falling observer 1 approaching the event horizon of a black hole. Evaluating his proper time, one finds that he crosses the event horizon...
  15. K

    Higgs Boson and Hawking Radiation

    Hey everyone, I'm new here. I'm currently a Grade 12 Student interested in Astrophysics, who has just recently applied to University (in Canada: UBC, UVic, UofT, UWO, Queen's, and York; all for Astrophysics and/or Astronomy, if anyone wants to give me advice on which one to choose, please do...
  16. D

    Black holes & hawking radiation

    So we have an object falling into a black hole. By its perspective it falls in real time, and by the perspective of the outside it never reaches the event horison. Now if black holes slowly evaporate due to hawking radiation, if one were to observe the black hole for countless billions of years...
  17. J

    Is there a good introduction to Hawking Radiation?

    I am just an undergraduate student of physics and I would like to know what would be the best (most pedagogical) introduction to Hawking Radiation.
  18. C

    Hawking radiation - please explain

    My understanding is that Hawking's radiation is a theory used to explain how black hole's conserve energy. For example, we think black holes grow in size as they consume matter. Any particle that enters the Schwarzschild radius (SR) of a black hole is absorbed. QM purposes that virtual...
  19. jal

    Is dark energy from cosmic Hawking radiation?

    http://arxiv.org/abs/0803.1987 Is dark energy from cosmic Hawking radiation? Authors: Jae-Weon Lee, Hyeong-Chan Kim, Jungjai Lee (Submitted on 13 Mar 2008) We suggest that dark energy is the Hawking radiation from a cosmic horizon. Despite of the extremely low Hawking temperature this dark...
  20. S

    Hawking radiation & Information loss

    What if there is no hawking radiation i.e if it is not proved..i think it is not yet proved...so will it have any influence on information loss paradox..if there is no hawking radiation then the information would be inside black hole and not accessible..so there is no information loss paradox if...
  21. S

    Hawking Radiation: Observational Proof, Quantum Fluctuations & More

    1. Do we have observational proof for hawking radiation? Or is it verified only theoritically? 2. why is that only negative energy photon goes into black hole and positive energy photon is going out from black hole? what if the reverse happens? do we have an observatinal proof for this? 3. can...
  22. R

    When does Hawking radiation start?

    As I understand it, a black hole is supposed to evaporate through Hawking radiation after a long but finite amount of time. Also, the radiation encodes in some sense the information of the matter that fell into the black hole. This according to an observer ("Alice") outside the event horizon...
  23. R

    How can you find out the amount of hawking radiation a black hole exhibits?

    How can you find out the amount of hawking radiation a black hole exhibits? Rube cuber, Merry Christmas
  24. J

    Another hawking radiation question

    i am trying to understand hawking radiation. in wikipedia, it states: "In order to preserve total energy, the particle which fell into the black hole must have had a negative energy (with respect to an observer far away from the black hole). By this process the black hole loses mass, and to...
  25. P

    Hawking Radiation: Does an Astronaut Ever Cross the Horizon?

    Something I've been wondering for a while, but haven't been convinced by the answers I've received. If an astronaut falls into a black hole, from the perspective of us outside he never actually reaches the horizon. From his perspective, he falls straight through and doesn't notice any...
  26. A

    Hawking Radiation and Black Hole Evaporation

    I've been trying to discover a qualitative description of Hawking Radiation and Black Hole evaporation and haven't been able to find one yet. I figured this board might offer some insight. Can someone explain to me how a 'virtual' pair differs from a 'real' pair? It seems to me that no...
  27. E

    The Fine Structure Constant and Hawking Radiation

    Abstract. Theory of quantum gravity is still a mystery, as well as the derivation of fine structure constant and masses of elementary particles. (Fine structure constant is calculated from force between two elementary charges.) Possibility that elementary particles are black holes is offering...
  28. S

    Why Doesn't a Black Hole Absorb Hawking Radiation? Exploring the Mystery

    If black hole is so powerful, why doesn't it suck in Hawking radiation as well. I mean, it is just an electromagnetic radiation like light, right?
  29. S

    Where Does The Hawking Radiation Go?

    When a black hole evaporates it gives off Hawking Radiation. Where does the Hawking Radiation? Is it recycled into dark matter or new stars or what? Since mass and energy cannot be destroyed, it goes somewhere in the universe, correct?
  30. Loren Booda

    All spacetime horizons exhibit Hawking radiation

    All spacetime in our universe consists of gravitational horizons, the majority external (like that of the observable universe) or separate (like that of most black holes), either relative to a particular observer. Hawking radiation is therefore acting, albeit with very low flux, throughout our...
  31. R

    Why is Hawking Radiation Necessary for Black Hole Evaporation?

    I'm having trouble understanding why it is necessary for there to be a particle antiparticle pair formation in order for the black hole to evaporate. According to my understanding of the theory, a particle anti particle pair are formed, and rather than colliding within a given period of time...
  32. A

    Hawking Radiation: Particles, Black Holes & Dark Matter

    I was thinking you know hawking radiation where a virtual particle can escape, is it specific as to which particle can escape as in the particle or it's anti particle? does that make a black hole like a particle 'producing' machine, can these escaped particles be a significant fraction of the...
  33. E

    Why Does the Unruh-Hawking Model Precisely Predict a Thermal Radiation Spectrum?

    I have the following article for explanation of Hawking - Unruh radiation: http://arxiv.org/PS_cache/quant-ph/pdf/0401/0401170.pdf . It is the most simple explanation of Hawking radiation until now. Peoples try to find microscopic explanation of this, but, thermal properties of matter are...
  34. U

    Hawking radiation, Is it possible?

    According Hawking radiation theory the black holes eventually will evaporate. This process gives energy. The process of black hole creation also gives energy. The accelerating particles emit x-rays while falling into a black hole. Now we can construct perpetuum mobile. We create a black hole...
  35. W

    Solving Shrodinger Equation for Hawking Radiation

    I hear this is a result of quantum tunneling, what I am wondering is, can one solve the shrodinger equation for black holes under the idea that it is just a really really really deep finite well?
  36. S

    Hawking Radiation: violate laws of conservation?

    I was thinking, when virtual particles come into exsistance and then one particle go into a black hole and the other gets emmited as hawking radiation and so the particles are no longer virtual and become "real" particles. Does this violate the laws of thermodynamics, and so is the mass/energy...
  37. M

    Understanding the Math Behind Hawking Radiation

    I am currently taking Advanced Physics Topics class and am doing a research project on Hawking Radiation I was wondering if anyone knew of a free source I cold use that could explain the math behind the radiation a little better. I have looked on a few websites for information and have found...
  38. M

    Explaining Hawking Radiation in Detail

    Could someone explain to me, in excrusiating detail, Hawking Radiation, to include Hawking math and steps leading to the formation of the equations used to define and descibe it. It would be much appreciated. THANK YOU!
  39. wolram

    Hawking Radiation: Theory & Acceptance in Quantum Physics

    In cosmology Hawking radiation, is often quoted as a way Black Holes evaporate. http://en.wikipedia.org/wiki/Hawking_radiation AFAIK there is no way this can be tested other than getting up close to a BH, so is HR accepted in the quantum phys world, as a good model?
  40. N

    Hawking radiation and BH evaporation time

    I don't know a lot about this topic so corrections are solicited. My understanding is that black holes evaporate by Hawking radiation. Hawking radiation, by my reading, occurs when a pair of virtual particles emerges very close to but just outside the event horizon of the black hole. When...
  41. R

    Hawking Radiation – Empty space virtual antiparticle-particle pairs

    In reviewing explanations on evaporating Black Holes using Hawking Radiation, based on how the black hole might treat Quantum “Vacuum particle pairs”. Although direct observation of Black Hole radiation has not been confirmed it implied that “Antiparticle – Particle creation, and self...
  42. T

    Infinite Time and Hawking Radiation

    Let's say you decide to walk backwards into a black hole. Everything looks normal at first but as you get close everything is speeding up. When you're really close everything is going extremely fast. As you cross the event horizon, infinite time passes. (I know saying "infinite time passes" is a...
  43. J

    Black holes and Hawking radiation

    Please correct my question if I am again misguided. Theoretically not even light is able to escape the gravity of a black hole. Due to the curvature of space the black hole prevents anything or any information from coming back through the event horizon. However Blackholes are supposed to...
  44. I

    Is the existence of Hawking Radiation compatible with the Big Bang theory?

    I had this thought today after reading about Professor Hawking's recent lecture. If the suppsed Hawking Radiation truly exists then since all matter was supposedly concentrated into a singularity in the time before the big bang (if there was one); then this single black hole must have...
  45. 2

    Analogous Hawking Radiation from Astrophysical Black Hole Accretion

    Hi everyone Im trying to understand a paper(title of the thread) arxiv.org/abs/astro-ph/0404482 Just woundering what an acoustic black hole and acoustic event horizon would actually be? Is the Analogous Hawking Radiation just ascoustic osccilations in the Accretion matter? like the...
  46. T

    Throw hawking radiation theory out the window

    if an alone black hole is radiating gamma rays that's called hawking radiation that means its losing energy (because gamma rays aren't matter) but whatever size it is it dosen't lose energy that's why black holes go faster and faster the smaller it gets. Here is two main components why i say...
  47. Orion1

    What is the Wavelength of Hawking Radiation?

    One of the real important aspects of Hawking Radiation is the Kerr Temperature. Note that the Kerr Temperature is responsible for the Kerr Particle Energy Spectrum and represents the genesis of Thermodynamic Quantum Gravitation. Thermodynamic Quantum Gravitation is the combination of...
  48. S

    Hawking Radiation 2 (different question)

    That last thread was pretty in depth, and I didn't understand a lot of it. But what I got out of it was, a virtual particle pair creates near the EH, one has positive energy one has negative, to satisfy the "ground state" vacuum. One particle falls in, the other escapes. So, can't...
  49. S

    Understanding Hawking radiation

    I think I have the general idea of how it works. But how does one particle get negative energy when it falls into the event horizon?
  50. P

    Questions on Hawking Radiation

    I've been reading about Hawking Radiation, and some questions have come up. 1) What exactly is a virtual particle? 2) What is negative mass and energy?
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