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. pittsburghjoe

    B Supervoid/Cold Spot evidence of Hawking radiation?

    Could this possibly be what the inside of a black hole looks like? aka our Universe resides in a black hole and this area is the event horizon slowly becoming more desolate as Hawking radiation occurs on the opposite side.
  2. Grinkle

    I What is the mechanism behind Hawking radiation?

    I thought Hawking radiation was a virtual particle pair emerging from nothing, one particle falling into the event horizon and the other particle tunneling out of the event horizon. Then I read this - https://www.physicsforums.com/insights/vacuum-fluctuation-myth/ and now I think a virtual...
  3. F

    I Create black hole with lasers? Physics project

    Hi! We have a projekt at the university and I have been thinking of creating a tiny tiny black hole after I've read some articles. I know one can create an artificial black hole with polarized laser pulses at a block of glass. And then one can measure a lot of things, usually hawkingradiation...
  4. T

    I Hawking Radiation: Explaining the Evaporation Effect

    I'm reading this article... "Hawking proposed that the Universe is filled with 'virtual particles' that, according to what we know about how quantum mechanics works, blink in and out of existence and annihilate each other as soon as they come in contact - except if they happen to appear on...
  5. victorhugo

    I Why does hawking radiation in black holes slowly increase?

    First, what are these 'particles' that appear with their negative mass counterpart and suddenly disappear very quickly and why do they do that? Now, I know the positive mass ones are allowed to escape the event horizon while the negative mass doesn't, thus fall into the black hole, but how does...
  6. P

    I Question about Hawking radiation

    So hawking radiation is a phenomenon thwt happens when a pair of particle-anti particle are generated from vacuum according to Heisenberg uncertainty principle at the horizon of e event is that right? And the negative particle "falls" into the black hole while the positive one escapes as hawking...
  7. nomadreid

    I Observing Hawking Radiation from Inside a Black Hole

    Usually Hawking radiation is treated from the point of view of an observer outside the black hole (by which I mean the event horizon, not the supposed singularity), in which case it is possible (although maybe not convenient) to treat the black hole as not having an interior. However, let us...
  8. Buzz Bloom

    I Hawking Radiation: Qs re Energy Density at r > Rc

    In my Part I post https://www.physicsforums.com/threads/qs-re-hawking-radiation-part-i.873163/reply?quote=5482437 I asked if there were any errors in my summary description of the Hawking radiation phenomenon. So far none have been posted. In this thread I want to learn some additional facts...
  9. Buzz Bloom

    I Qs re Hawking Radiation – Part I

    I am starting this thread to continue asking questions regarding the Hawking Radiation phenomenon which were discussed in the Comments thread about the Insights article “Misconceptions about Virtual Particles”. This discussion has been mostly a dialogue between A. Neumaier and myself starting...
  10. R

    I Hawking radiation and energy-negative energy pair production

    A black hole evaporates through hawking radiation, what I don't get is the requirement for an energy-negative energy pair production. Since it's the black hole's gravitational energy that's responsible for the pair production, even if one of them escapes, the black hole would lose energy anyway...
  11. TeethWhitener

    B Hawking radiation / String Hagedorn temperature?

    I was playing around with numbers and found that the equivalent temperature for Hawking radiation from a Planck mass black hole is ~5×1030 K. Later, I saw that the Hagedorn temperature for strings (where the partition function is expected to diverge) is reported to be around ~1030 K. I thought...
  12. Stephanus

    Understanding Entropy and Hawking Radiation in Black Holes

    Dear PF Forum, I'm trying to make sense about Hawking radiation in Black Hole. And that leads me into entropy. I read this equation in https://en.wikipedia.org/wiki/Entropy What does that mean? S is the change of Entropy What does Qrev mean there? Is it in Calorie? then Joule? T, I think is in...
  13. Chris11235

    General Relativity and Hawking Radiation at the Event Horizon

    The question is to resolve a logical conflict. GR says as we fall into a black hole, an outside observer will see that event come to a stand still as if the falling object is hovering at the horizon. This stand still extends to infinite time. Unfortunately, I've read and hear the term...
  14. wolram

    B Black Holes and Hawking radiation

    Is there a limit as to how much a black hole gathers mass and how much it losses mass via hawking radiation so that the black hole becomes in equilibrium, neither gaining mass or loosing mass How long would it take a hypothetical isolated black hole to loose one solar mass due to Hawking radiation.
  15. S

    Confused about black holes and Hawking radiation

    Why is it that the smaller the black hole is, the more quickly it supposedly evaporates? It seems like a black hole should radiate energy proportional to the surface area of the event horizon. To me it seems like the evaporation should slow down the more the black hole shrinks because the energy...
  16. N

    Hawking radiation from not-a-black-hole?

    Since Schwarzschild solution describes exterior not only of black holes, but of any spherically symmetric non-rotating objects, then any such object should emit Hawking radiation, no? Then how exactly is that working? Let's set up a thought experiment. Say, we construct a spherically symmetric...
  17. W

    Hawking radiation no change to black hole mass?

    have read numerous times about Hawking radiation. don't understand how that can lead to black hole evaporation in so much that wouldn't as many matter as anti-matter particles fall in thus balancing out over time to the growth and evaporation of black holes thus leaving the mass of the balck...
  18. Jaami M.

    How does Hawking Radiation work?

    I'm very new to the understanding of Hawking Radiation. I don't know much about this theory, but I do know that Hawking radiation works on a Quantum scale. I know that with black holes this theory proposes th idea that over time black hole lose mass because of "Spontaneous appearing positive and...
  19. L

    Why do Black Holes evaporate due to Hawking radiation?

    A book I read says that when virtual particle-antiparticle pairs are created near a black hole then sometimes one of the particle pairs will be captured by the black hole while the other one will be freed to move away as a real particle - then this causes the black hole to lose mass and thus...
  20. T

    Z-bosons as Hawking radiation from BH

    Please check my logic. 1. Hawking mechanism should give birth not only to photons, but also to their heavier analogs, Z for example. 2. Contrary to photons, massive Z bosons are not gradually red shifted, low energy Z simply fall back to BH, so the "red" part of the black-body spectrum of Z is...
  21. Stephanus

    Quantum tunnel into becoming solid iron

    Dear PF Forum, I have no background in physics :frown: In http://math.ucr.edu/home/baez/end.html 1. If an Earth size object is left alone (assuming the Sun won't swallow it 2 billions year later). In 101500all of it atoms, oxygen (majority abundant in earth, right), silicon, nitrogen (abundant...
  22. M

    Exploring Hawking Radiation Emission Process

    So I realize that I'm probably wrong about this, but it seems to me that Hawking radiation cannot be emitted only at the event horizon. If we make the (albeit almost certainly wrong) assumption that the quantity of emitted particles is directly proportional to the potential for gravitational...
  23. ChrisVer

    Is Hawking Radiation a Kinematic Effect or a Real Phenomenon?

    Has the Hawking radiation ever been observed from bodies like black holes or in laboratory? From what I saw, it hasn't... 1. What are the difficulties? 2. Why are we using Hawking Radiation in some reasonings, since we haven't observed it really happening?
  24. W

    Does Hawking radiation take place at the apparent horizon?

    When the apparent horizon differs from the event horizon, as in the case of an observer falling into a black hole, does Hawking radiation take place at the former, the latter, or both?
  25. A

    Hawking radiation prevents event horizon crossing?

    No one seems to be bothered by this except me: Black holes have a finite lifetime measured in Schwartzchild time due to Hawking radiation. Similarly, the universe probably has a finite lifetime measured in Schwartzchild time. In that case, nothing ever falls through the event horizon of a black...
  26. C

    I How does Hawking radiation contribute to the formation of new stars?

    Hawking radiation talk about particles emitted from black holes. Are the particles emitted are protons and electrons? (emitted at near light speed and gradually slowdown by gravity pull of black hole as the particles move outward to fill the interstellar space of the galaxy) If yes, that means...
  27. C

    Hawking Radiation: The Role of Electromagnetism in Black Hole Evaporation

    Hello When virtuals particles appears near a black hole , the one with a negative charge is attracted by the black hole , and as mass is proportional to energy , the black hole "evaporates" . My question is , why the particle attracted is always the one with the negative charge , is it because...
  28. stevebd1

    Old article on Hawking radiation

    Maybe this article is more readily available than I'm aware of but thought it would be of interest to some- 'The Quantum Mechanics of Black Holes' by Stephen Hawkings http://planck.phys.uwosh.edu/rioux/thermo/pdf/Black%20Holes%20--%20Hawking.pdf
  29. Abishek

    Black Holes & Hawking Radiation: Time Paused in Gravity?

    In the view of Hawking radiation and entropy of black holes, the evaporation is continuous and at one point, there will be no singularity for the black hole. By relativity, if we reach a super massive black hole, then time would be relatively slowed down to a point that it stops (maybe?). Now...
  30. avito009

    How Does Entropy Influence Hawking Radiation in Black Holes?

    I know that entropy is a measure of disorder. But Entropy is also a function of the state of a system, and has a value determined by the state variables of the system. Does that mean Entropy describes the equilibrium state of a system. Please explain in layman terms in this context what is...
  31. B

    Hawking radiation temperature -- observer dependent?

    Black holes are claimed to radiate at a temperature corresponding to the hawking radiation. But who is measuring the temperature? If the radiation is measured from far away the red shift will indicate a lower temperature won't it? Is the temperature given by the formula as measured from a...
  32. B

    Hawking Radiation from All Gravitational Sources?

    I see that the formula for hawking radiation is related the the formula for unruh radiation. The accelleration experienced by a body yields an unruh temperature equivalent to a black holes hawking temperature with an equivalent value of g. The unruh effect happens at all accelerations, therefore...
  33. J

    Understanding Hawking Radiation: Energy Subtracted from Black Holes

    Something I don't understand is how the energy is subtracted from the black hole. So let's say one pair of virtual particles pop up on the event horizon, the particle goes in, the antiparticle goes out. Then let's say that a second pair does the opposite. My first question is why is the...
  34. .Scott

    Hawking Radiation and Entanglement

    I am at odds over how Hawking Radiation can cause a problem with entanglement - or even how the pair particle to a Hawking particle can enter a black hole. The notion behind Hawking Radiation, as I understand it, is that a particle divides above the event horizon creating two entangled...
  35. bcrowell

    Were Hawking Radiation & Singularity Theorem Controversial in 1965?

    I just saw The Theory of Everything, which is a Hollywood biopic about Stephen Hawking. Of course the physics content had to be watered down and made to serve dramatic and thematic purposes, but a couple of historical points seemed interesting and made me wonder whether they were real: 1...
  36. Lamdbaenergy

    Hawking Radiation From Black Holes:

    If you only knew the temperature of the black hole, like, if for example, the temperature of a 4 solar mass black hole being around 1.5e-8 kelvin, how could you possibly be able to calculate what wavelengths of radiation the black hole would give off? Would a black hole like this really only...
  37. MattRob

    Black Hole Hawking Radiation: Frame-Dependent Virtual Particles

    I was reading "Black Holes and Time Warps" by Kip Thorne, and right around p.442-443 it talks about how the quantum vacuum fluctuations that give rise to Hawking radiation from an infalling frame of reference give rise to an "atmosphere" of real, non-virtual particles in an accelerated frame...
  38. M

    Is Hawking radiation lethal?

    Wow! Thanks to all for this great resource. Would it be possible to cast light harmlessly by spontaneously creating microscopic black holes of small enough mass? Or would you necessarily get high-frequency X and gamma radiation along with visible light?
  39. bcrowell

    Backreaction from Hawking radiation may prevent formation of event horizon?

    I'm trying to understand the ideas in this paper at a nontechnical level: Laura Mersini-Houghton, "Backreaction of Hawking Radiation on a Gravitationally Collapsing Star I: Black Holes?," http://arxiv.org/abs/1406.1525 She says: This work investigates the backreaction of Hawking radiation on...
  40. J

    What is the Connection Between Hawking Radiation and Dark Matter?

    The way I understand Hawking radiation is that black holes decay by sucking in anti particles from the virtual particle pairs that are created right at its event horizon. I also understand that these anti particles reduce the mass of the black hole instantly when crossing the event horizon? And...
  41. Greg Bernhardt

    What are the effects of Hawking radiation on black holes?

    Definition/Summary Hawking radiation is black body thermal radiation predicted to be emitted by black holes due to quantum effects- 'The vacuum in quantum field theory is not really empty; it's filled with "virtual pairs" of particles and antiparticles that pop in and out of existence...
  42. ghost313

    Hawking Radiation Explained: How Particles Escape from Black Holes

    So we are at a distance from the black hole R>2GM/c^2 where quantum fluctuations happen all the time. How is it possible that every time the anti-particle ends up in the black hole(the one that will decrease her mass) and eaven if it's so,how can the other particle escape?if they are at a really...
  43. Matterwave

    Regarding the Hawking radiation

    Hello guys. From my understanding of the Hawking radiation, it is a consequence of QFT in curved space time. The fact that a uniformly accelerated observer sees the Unruh radiation means that by the equivalence principle, a stationary observer at a distance from a black hole will see Hawking...
  44. M

    The black Hole Wars - Losing Information in the Hawking Radiation

    So as I understand it, Hawking theorized that due to the behaviour of virtual particles on the event horizon of a black hole, eventually the black hole would "evaporate" through what was coined the Hawking Radiation. But what I'm curious about is Hawking's interpretation of the event in that...
  45. K

    The Hawking radiation and information paradox

    Here is my understanding, please correct me if I made any mistake Quantum physics theory suggests that information (the wave function, state, etc.) cannot be destroyed. All matters fall into a black hole will not be able to escape, which means all information of these particles stay inside...
  46. L

    Hawking Radiation and the Decay of Black Holes

    Hawking Radiation and the "Decay" of Black Holes I have been doing a lot of reading and thinking about certain quantum mechanics so that I can try and wrap my head around how it all works. However I have come upon something that I cannot find a good explanation for. I was reading about...
  47. craigi

    Unruh and Hawking Radiation Paradoxes?

    Does the existence of observer dependent particles as predicted by the Unruh effect and Hawking radiation lead to paradoxes?
  48. A

    Hawking radiation and information

    say you measured every particle which has entered a black hole say you measured every hawking radiation particle which exits the black hole my understanding is that if like... a proton enters the black hole, then an anti-proton needs to be emitted via hawking radiation. so if you measure...
  49. A

    Explaining Hawking Radiation & Its Effect on Black Hole Mass

    From what I understand, Hawking radiation results when one virtual particle (of the pair) falls into the black hole while the other escapes... See I understand why the virtual particles don't come back together - because one is created beyond the horizon while the other is not. But how...
  50. P

    Question about relativistic quantum hawking radiation.

    So as I understand it Stephen Hawking and one other person I can't remember the name of worked on an equation to described the "temperature" of a black hole, that you can actually get information out of it. I know that there is one way it could happen with those vacuum particles in vacuum energy...
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