What is Hawking radiation: Definition and 204 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. ShadowKraz

    I Questions about Black Holes, Hawking Radiation, and Dark Matter

    If this post should be in another forum, please advise so I can post there instead. I hope I got the right prefix. Thank you. 1) Is it possible for Hawking Radiation to be dark matter, at least in part? Do the equations rule out this possibility? 2) Are Black Holes actually spinning or is our...
  2. S

    I Supressing black hole evaporation?

    A very massive charged black hole could reach a near-extremal state in the right conditions supressing the rate of emission of Hawking radiation (https://physics.stackexchange.com/questions/490524/evaporation-of-large-charged-black-holes) Meanwhile, the radiation emitted by a black hole can be...
  3. S

    I Questions about Hawking radiation and extremal black holes...?

    I'm studying if there is some way to avoid black hole evaporation, even if it requires a very special set up of conditions... Theoretically, extremal black holes (both for rotating Kerr and Reissner-Nordström ones) would avoid evaporation as they would not emit Hawking radiation. Since...
  4. G

    Black hole evaporation mechanism

    [post moved to relativity forum: https://www.physicsforums.com/threads/black-hole-evaporation-mechanism.1059236/]
  5. W

    I If nothing can escape a black hole, it follows that Hawking radiation can't exist?

    Or is Hawking radiation something? Can't be both, however if you choose one theory over another, why do you do so. Those of you who are younger will not remember a World without the information paradox, but when I was younger it did not exist in any way because nothing escaped the event...
  6. Demystifier

    A Negative energy in Hawking radiation

    At a descriptive level, negative energy quanta enter a black hole during Hawking radiation. But when one tries to understand it mathematically, it seems that negative "energies" appear in two very different senses, which seem to be totally unrelated to each other. At one level one has Bogoliubov...
  7. KDP

    I Brian Cox and the end of the Universe?

    Professor Brian Cox was on the TV last night. He stated that eventually everything will end up in black holes. When there is nothing left to absorb they will start evaporating via Hawking radiation until eventually they all disappear in a small flash of light and then there will be eternal...
  8. D

    I What is the Limiting Mass at the Final Stages of Black Hole Evaporation?

    As Hawking radiation does away with black holes in the eons of time it takes to evaporate, what is the limiting mass at the final stages of the black hole evaporation? Is it Planck mass? or some fractional mass of the initial BH?
  9. S

    I DeSitter cosmological horizon stability?

    If the universe keeps expanding at an accelerated rate (given by the cosmological constant) then the universe would approach a DeSitter spacetime where there would be a cosmological horizon that would radiate just as the event horizon of a black hole radiates Hawking radiation I thought that...
  10. M

    I Hawking Radiation Extrapolation: A Conjecture

    The intense gravity near the event horizon causes complementary particles to pop into existence spontaneously. As local space-time is continuous through the EV, the same would be happening just inside the EV, only more so as the gravity field and gradient is greater. So near the singularity...
  11. M

    I  Hawking Radiation: Can Particles Appear with Relativistic Velocities?

    The Hawking radiation comes from a pair of complementary particles, an electron and a positron for example, coming into existence spontaneously near the event horizon as a result of the intense gravitational field. One particle gets captured by the Black Hole while the other escapes, taking a...
  12. P

    B Can Particles Escape a Black Hole? The Hawking Radiation Improbability

    How can a particle created just outside the event horizon with no velocity (?) escape a black hole, never to return, when black holes gravity is so strong that they can pull matter away from stars many kilometers distant?
  13. nomadreid

    I Entangled particles in black hole decay?

    First, I was not sure whether this should go into the Relativity or the Quantum Physics rubric, but since the central question is about entanglement, I opted for the Quantum. I do not have the necessary sophistication to follow string theory arguments, and even most explanations in...
  14. AdvaitDhingra

    QFT interpretation of Hawking Radiation

    Hello, So I was reading about Hawking radiation and I read a QFT interpretation of it. It went something like this: A vacuum contains virtual particles (vacuum energy), which in qft can be described as waves that are out of phase and cancel each other out (matter and antimatter). I a black...
  15. M

    I Observe Hawking Rad. in Black Hole?

    Theoretically could an observer in a black hole perceive hawking radiation escaping the black hole as a black hole within the black hole? Also if so maybe that black hole could produce a radiation similar to or related to hawking radiation (Making a strange entangled system for conservation of...
  16. G

    I Hawking Radiation: Info vs Semanticity? - Hossenfelder

    In this video How we know that Einstein's General Relativity can't be quite right - YouTube , Hossenfelder says: "The [Hawking] radiation is entirely random and does not carry any information..." I have heard and read this from a number of other sources, and never understood. Completly random...
  17. M

    B Can You Fall Into a Black Hole? Exploring Time & Decay

    It takes infinite amount of time to cross the event horizon from an outsider's perspective. But black holes eventually decay from Hawking radiation. So if you wait long enough a black hole won't exist anymore, as it would have decayed into nothing. The in-falling observer witnesses infinite...
  18. docnet

    I Black Hole Evaporation: Exploring Hawking Radiation and Shrinking Black Holes

    I am grateful for anyone for their time to answer this question. Some theories predict black holes will evaporate and eventually disappear. From my limited understanding, Hawking's theory predicts that quantum effects near the event horizon of a black hole are responsible for blackbody...
  19. hideelo

    A Hawking Radiation: Understanding Complexity in Black Holes

    If we take the perspective that black holes thermalize (reach maximum entropy) in a very short time and then just sit there and grow in complexity, how do we interpret Hawking radiation in this picture? i.e. you can't just have the state of the black hole keep growing in complexity forever...
  20. Castty

    B Infinite Curvature & Hawking Radiation Explained

    Hi, i have a question which i can't solve myself, as i am not a student of physics: I have heard of the infinite space curvature which occurs when matter collapses into a black hole. On the other hand i have heard, that a black hole radiates energy away. Now i see a contradiction: When the...
  21. E

    A Validity of theoretical arguments for Unruh and Hawking radiation

    [Moderator's note: New thread spun off from previous discussion due to more advanced subject matter being discussed.] There is, in fact, a quite good argument that Hawking radiation cannot be derived by semiclassical theory. It is the comparison with the scenario where the collapse stops some...
  22. P

    A Hawking Radiation Inside a Black Hole: Theory & Possibilities

    It is known theoretical prediction that Black Holes must emit radiation "... its temperature and surface gravity are proportional to its mass divided by its area" (Kip Thorne). This is applied to Event Horizon (rg). But one can imagine inner Black Hole (e.g. inside r' < rg), it does not have...
  23. A

    B A little logical doubt on Hawking radiation

    Summary: As hawking radiation is based on quantum fluctuations, can they cancel out each other due to equal probabilities of a particle remaining in or drifting away? I recently learned how hawking radiation actually works. It is based on quantum fluctuations which happen randomly in space...
  24. A

    I Falling Into a Black Hole: Time Dilation & Hawking Radiation

    I know that has been discussed elsewhere but never could find for a satisfying answer, so I try this here again. Let us not take into account that an observer (an astronaut or a clock or just let us take both: an astronaut with a clock) falling into a black hole (BH) will be killed and torn...
  25. L

    A Quantum amplitude for a particle falling into a black hole

    Here we consider a black hole formed by gravitational collapse classically. We also consider a scalar massless Klein-Gordon field propagating on this background. To quantize the field we expand it in appropriate modes. The three sets of modes required are: The incoming modes, appropriate for...
  26. Robert Friz

    B Hawking Radiation and Shrinking Black Holes

    Stephen Hawking theorized the creation of virtual particle pairs at the event horizon of a black hole, with one of the particles escaping the event horizon (Hawking Radiation) and the other particle falling into the black hole. Sean Carroll states on page 272 of From Eternity to Here that "if...
  27. P

    Confused about Hawking Radiation

    Hawking Radiation says that an antiparticle and particle spontaneously appear and annihilate each other everywhere, but at the horizon, if the antiparticle appearing inside the horizon and the particle appears outside, then the antiparticle is sucked in and the particle is emitted outward...
  28. S

    Hawking radiation versus the cosmic background

    Is the cosmic backround radiation incident on a black hole sufficient to make up for the energy lost through Hawking radiation? And what if we include the average energy flux from discrete objects like galaxies, as seen in intergalactic space?
  29. avischiffman

    I Can someone fact check my speech about BH?

    Hey everyone, is anyone able to check the facts of this speech I wrote? I have 3 minutes max to say this, I might cut out tiny parts to save seconds. What do you guys think, is this correct? Should I change anything? Thanks! How Black Holes work Stars are massive collections of mostly hydrogen...
  30. Islam Hassan

    I Hawking Radiation and the Negative Energy Particle

    The following from Wiki re Hawking Radiation:“... 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 while the other escapes. In order to preserve total energy, the particle that fell into the...
  31. Pouya Pourkarim

    I Why is Hawking Radiation Unequal for Matter & Antimatter?

    we say everytime a couple of matter-antimatter particles get born near the edge of a black hole one of them falls into it and the other one escapes. And we everytime mention that the antimatter particle kind of eats a bit of black holes mass out...and by time the black hole gets smaller and...
  32. Z

    B Hawking radiation and entanglement

    I have been considering Hawkin radiation and I am puzzled about the capture of a virtual photon. Given that the escaped photon is entangled with the captured photon I do not see how the escaped photon can shed the entanglement. Can anyone help with this?
  33. F

    I Negative Mass and Hawking Radiation

    Matter with negative mass, herein called “negative matter”, is different from antimatter. P.A.M. Dirac, on theoretical grounds, proposed the existence of antimatter, and its existence was later confirmed by experiment. Antimatter is the opposite of ordinary matter in some ways, but just as...
  34. haushofer

    A Hawking radiation: pair production?

    Dear all, I'm trying to understand the firewall controversy and the role of Hawking radiation in this. To make things concrete, I'll use the desciption of the firewall controversy of John Preskill here...
  35. H

    A Hawking radiation and rotating Black holes

    Hawking radiation formula shows the fact that when charge and angular momentum increases in a Kerr-Newman black hole (angular momentum in Kerr black hole) Hawking radiation decreases. Can someone explain this? Thank you.
  36. Leyzorek

    I Methods of Hawking radiation generation

    first question From what i read Hawking radiation is a particle and ant particle created on the event horizon of a black hole, one particle is pulled into the black hole letting the other escape, why does the one outside of the event horizon escape instead of both being pulled in? It would still...
  37. T

    I Is Hawking Radiation unique? (And one more question)

    Are there kinds of black hole radiation other than that proposed by Hawking? Note that I'm talking about truly black hole radiation, not radiation from matter that orbits the black hole, etc. How can we conciliate such phenomenon with General Relativity? I mean, this seems to completely...
  38. durant35

    I Hawking radiation from de Sitter horizon

    I have some questions regarding the temperature of empty space in a de Sitter universe or to say it better - the Hawking radiation emmited from the cosmological horizon: 1) Do particles that make up the radiation get produced by the empty space inside the patch (the Bunch Davies vacuum) or by...
  39. J

    A Hawking and Unruh effects -- Differences and interpretations

    Hello, I am a bit confused on the relation between the Hawking effect(radiation) and the Unruh effect. What I understood with my little knowledge is that the Hawking temperature is the temperature that is emitted at the event horizon of a black hole as measured by an observer at infinite spatial...
  40. A

    I Black hole - event horizon and Hawking radiation

    I have come across the following multi-explanations of how Hawking radiation/evaporation of a black hole happens: Particle/anti-particle story: particle/antiparticle pair creation from vacuum near the event get torn apart - one going into black hole, the other away; in some of these...
  41. Allen_Wolf

    B Exploring Hawking Radiation: A 10th Grader's Curiosity

    Recently I was actually stuck on a thought about hawing radiation. If quantum fluctuations cause virtual particles to occur from space. So, to maintain the balance of mass in the universe, the particle with -ve energy should be having -ve mass, right? If so, by Newton's equation of gravitation...
  42. SlowThinker

    B  Charged Black Hole Hawking Radiation: Answers to Questions

    I was thinking about the title but after searching Arxiv, PF and the internet in general, my confusion has only increased. I have a few questions: 1. Often I see units where ##G=c=\hbar=1##, but what is the charge of an electron in these units? Everyone says M=Q as if it was somehow obvious how...
  43. C

    B How does Hawking radiation work?

    When reading about this subject on the internet, I found two ways how it works and I don't know which one is correct. 1: A particle pair is created near the black hole horizon. So there is an antiparticle and a particle. The antiparticle gets sucked into the black hole but because the...
  44. C

    How exactly does Hawking radiation work?

    Homework Statement For school I'm doing a project on hawking radiaton but I have very big difficulties trying to understand it. I'm trying to understand the matter about: Unruh effect, particle pair (antimatter - matter) and the theory of relativity regarding vaccuum. Homework Equations none...
  45. H

    Studying Rotating black hole & Hawking radiation research

    I am an undergraduate student of a university, I have taken the research topic as Study of Rotating black holes and Hawking radiation which I am really interested. Research description as follows. The geometric invariant are computed in various black hole geometries in several different...
  46. J

    I Is proton decay considered in neutron star models (and LHC)?

    Although it is definitely not simple, there are many reasons to consider that baryon number can be violated, for example: - while baryogenesis there was created more matter than antimatter, - hypothetical Hawking radiation can finally turn any matter (mainly baryons) into massless radiation...
  47. stevendaryl

    A Information Paradox for Unruh Radiation?

    I'm sure that there are limits to the analogy between the event horizon of black holes and the "Rindler horizon" for an accelerated observer, but there are a number of similarities: For Schwarzschild spacetime as described in Schwarzschild coordinates: Spacetime is static, and a rocket must...
  48. D

    B The Singularity and Hawking radiation

    Hello everyone! Im a newcomer, a teenager who has countless doubts with respect to relativity, quantum theory etc. But these two questions bother me the most: 1) Hawking radiation states that when the separation of a particle (eg. a photon) into charged particles happens in the event horizon...
  49. Buzz Bloom

    I Questions regarding Hawking radiation

    The following are a few questions to help me understand the variability of views about Hawking radiation held by various knowledgeable PF QM physicists. 1. Do you personally believe that Hawking radiation is a real phenomenon rather than a only a theoretical possibility? 2. What percentage of...
  50. J

    Hawking Radiation: Exploring Mass & Temperature Changes

    Hello, I am rather new to Physics and for a class project on exponential growth and decay in nature and I chose the effects Hawking Radiation on black holes. If anyone could help explain how the mass and temperature change over time and how to calculate them(this one especially) that would be...