What is Hawking: Definition and 329 Discussions

Stephen William Hawking (8 January 1942 – 14 March 2018) was an English theoretical physicist, cosmologist, and author who was director of research at the Centre for Theoretical Cosmology at the University of Cambridge at the time of his death. He was the Lucasian Professor of Mathematics at the University of Cambridge between 1979 and 2009.
Hawking was born in Oxford into a family of doctors. He began his university education at University College, Oxford, in October 1959 at the age of 17, where he received a first-class BA (Hons.) degree in physics. He began his graduate work at Trinity Hall, Cambridge, in October 1962, where he obtained his PhD degree in applied mathematics and theoretical physics, specialising in general relativity and cosmology in March 1966. In 1963, Hawking was diagnosed with an early-onset slow-progressing form of motor neurone disease that gradually paralysed him over the decades. After the loss of his speech, he communicated through a speech-generating device initially through use of a handheld switch, and eventually by using a single cheek muscle.
Hawking's scientific works included a collaboration with Roger Penrose on gravitational singularity theorems in the framework of general relativity and the theoretical prediction that black holes emit radiation, often called Hawking radiation. Initially, Hawking radiation was controversial. By the late 1970s and following the publication of further research, the discovery was widely accepted as a significant breakthrough in theoretical physics. Hawking was the first to set out a theory of cosmology explained by a union of the general theory of relativity and quantum mechanics. He was a vigorous supporter of the many-worlds interpretation of quantum mechanics.Hawking achieved commercial success with several works of popular science in which he discussed his theories and cosmology in general. His book A Brief History of Time appeared on the Sunday Times bestseller list for a record-breaking 237 weeks. Hawking was a Fellow of the Royal Society, a lifetime member of the Pontifical Academy of Sciences, and a recipient of the Presidential Medal of Freedom, the highest civilian award in the United States. In 2002, Hawking was ranked number 25 in the BBC's poll of the 100 Greatest Britons. He died on 14 March 2018 at the age of 76, after living with motor neurone disease for more than 50 years.

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  1. 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...
  2. 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...
  3. 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...
  4. 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...
  5. 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...
  6. .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...
  7. 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...
  8. T

    Spectrum of Hawking Raditaion

    Simple questions. There is a formula for the POWER of Hawking radiation, but what's about it's spectrum? What is the shape of the power/wavelength curve?
  9. 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...
  10. A

    Who do you think is more intelligent : Hawking or Tesla?

    Ok, I admit i am comparing apples to oranges - cosmologist to engineer. But if you were to choose one based on intelligence, who would it be? If you regard neither of these two men as the most intelligent man who has ever lived, who do you regard as such?
  11. 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...
  12. 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?
  13. 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...
  14. 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...
  15. liometopum

    Another issue with the Hawking equations

    I previously posted on the idea that the Hawking equations looked wrong: https://www.physicsforums.com/showthread.php?t=666962 I returned to this topic recently, and noticed something. If you multiply power by time, you should get energy. Multiplying the Hawking power by the evaporation...
  16. marcus

    Baryogenesis from Hawking Radiation--Anson Hook

    Video: http://pirsa.org/14070019 Asymmetric Hawking Radiation: Baryogenesis from Hawking Radiation Anson Hook Abstract: We show that in the presence of a chemical potential, black hole evaporation generates baryon number. If the inflaton or Ricci scalar is derivatively coupled to the B-L...
  17. 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...
  18. 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...
  19. 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...
  20. 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...
  21. twistor

    Stephen Hawking: Hilarious Interview - Watch Now!

    THAT'S AN EXTREMELY HILARIOUS INTERVIEW WITH STEPHEN HAWKING. What are your thoughts on it? https://www.youtube.com/watch?v=OPV3D7f3bHY
  22. darida

    Is the Hawking Mass Stable in Supergravity Theories?

    What is stability of Hawking Mass and how to calculate it? Any references will be appreciated. Thanks
  23. 1

    Do famous physicists (Kaku and Hawking) pass off asumptions as fact?

    Hello all, I will freely admit I suffer from Obsessive Compulsive Disorder, and now that it is well managed I tend to attach my obsessions over interest. One thing I tend to obsess about is the possibility of aliens. I think about the fact that us humans are the only technological creatures on...
  24. 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...
  25. 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...
  26. 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?
  27. 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...
  28. 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...
  29. zoobyshoe

    Hawking Says, There are no black holes.

    Hawking Says, "There are no black holes." More: http://www.nature.com/news/stephen-hawking-there-are-no-black-holes-1.14583
  30. 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...
  31. shounakbhatta

    Hawking radiation and its significance

    Hello All, I have been trying to understand the exact contribution of our legendary physicist, Dr.Hawking and found that Hawking radiation is amongst one. Is it that Hawking radiation is the first attempt to unify, general relativity, quantum mechanics and thermodynamics which led to the...
  32. Superposed_Cat

    How Does Hawking Radiation Influence the Black Hole Information Paradox?

    Hi all, to begin this is my understanding of hawking radiation. A particle/anti-particle pair is generated. one particle outside the event horizon of a black hole, the other inside. The gravitational force "boosts" the one particle into being real. this energy is compensated for by endowing...
  33. Superposed_Cat

    Light Entering Black Hole: Hawking Radiation Explained

    Hi all, I was wondering if, when a beam of light is pulled towards a black hole , because it can't accelerate, it is blueshifted? Thanks in advance.
  34. J

    The paradox of Hawking radiation - is matter infinitely compressible?

    The hypothetical Hawking radiation means that a set of baryons can be finally transformed, "evaporate" into a massless radiation - that baryons can be destroyed. It requires that this matter was initially compressed into a black hole. If baryons can be destroyed in such extreme conditions, the...
  35. darida

    Hawking Mass in Schwarzschild Spacetime

    Homework Statement Metric signature: - + + + Schwarzschild metric: dS^{2}=-(1-\frac{2M}{r})dt^{2}+(1-\frac{2M}{r})^{-1}dr^{2}+r^{2}d\theta^{2}+r^{2}(sin\theta)^{2}d\phi^{2} Second fundamental form: h_{ij}=g_{kl}\Gamma^{k}_{ij}n^{l} where: i=1,2 j=1,2...
  36. S

    Can't figure out how hawking radiation fixes thermodynamic problem

    Hi, I've tried several times to get my head around this, but every way I look at it Hawking Radiation doesn't seem to fix the thermodynamic issues it was supposed to solve. People who are a lot smarter than me seem to believe it's real, so can someone please point out where I'm going wrong...
  37. D

    Hawking Radiation and Shrinking Black Holes

    I was wondering whether anyone could provide an explanation as to why when two particles are created near the event horizon, only the negative energy particle is captured by the black hole, and the positive particle travels outward and is seen as Hawking Radiation. I have read numerous posts...
  38. K

    Free falling into a black hole that evaporates by Hawking Radiation

    The solution of Einstein's field equations for a simple black hole show a slowing of time as you get close to the black hole. Time stops at the event horizon. An observer in flat spacetime far from the hole would see an astronaut fall slower and slower as he approaches the event horizon. It...
  39. Greg Bernhardt

    Stephen Hawking warning that our extinction is on the horizon

    http://news.cnet.com/8301-11386_3-57579003-76/stephen-hawking-predicts-end-of-earth-scenario/
  40. B

    Why Stephen Hawking says universe can create itself from nothing?

    Hello all . I can not explain good but hope you will understand my purpose . I read in University Oregon's website that universe came from a pure energy in vacuum If we want to say exactly , we can say universe came from Potential energy in vacuum . We know in physics there are some...
  41. Q

    Hawking radiation and Black hole evaportion

    When the 'evaporation' of a black hole supposedly occurs, it is always attributed to 'Hawking radiation.' As I understand it, Hawking radiation occurs when a virtual particle pair is 'split' at the exact edge of an event horizon. When this occurs, one of the particle pair escapes to 'normal'...
  42. G

    Derivation of Hawking temperature

    Hi, my first thread. The Hawking temperature for a BH can be derived through compactifying the timelike dimension and hence identifying the time coordinate of the euclidean metric such as a periodic coordinate τ with period β. Now, very interestingly in the context of AdS/CFT correspondence...
  43. liometopum

    Are Hawking's Equations for Black Hole Energy and Evaporation Time Flawed?

    Hawking's equations for black hole energy, power, and evaporation time are unattractive. http://en.wikipedia.org/wiki/Hawking_radiation The energy equation, with its denominator of 8 pi GM, isn't too bad, but it has already been challenged as being off by a factor of two. See arxiv, "Black...
  44. Crazymechanic

    Hawking radiation , black hole size

    Hi. If the hawking radiation is emitted from outside the event horizon , because probably that's the last place where the particles are being able to escape, then how come huge black holes ever evaporate as the matter behind event horizon has no chance of escaping in any way as to the immense...
  45. C

    Time Before Big Bang: Stephen Hawking & Other Universes

    Can Stephen Hawking really claim that there was no time at all before the Big Bang when a black hole can have an outside observer on normal time? And what about other Universes in relation to our Universe? Don't they have a normal time at the time of our Big Bang?
  46. T

    Why do smaller black holes emit more Hawking radiation?

    Why is it that the smaller a black hole is, the more Hawking radiation it emits? It seems counterintuitive to me. I would think that a larger black hole with a larger surface area would trap more antiparticles from virtual particle antiparticle pairs, hence emitting more Hawking radiation.
  47. rjbeery

    Does Hawking Radiation preclude EH formation?

    Discussions involving Hawking radiation in the study of black holes usually require their preexistence; however, if we apply the Hawking radiation process to the initial stages of a birthing black hole I'm confused about how the theory claims the event horizon would form in the first place. In...
  48. U

    After watching the Stephen Hawking Series

    I just finished watching a few Stephen Hawking specials. I watched "Did God create the universe" and the one about black holes. I am by far not even close to knowing anything about Astrophysics, so please forgive my ignorance. I just found the shows interesting and have a few questions...
  49. L

    Why doesn't hawking radiation prevent a space-like singularity

    As I understand it, as a particle is observed approaching an event horizon, will would never be observed to cross the horizon, and it's red shift would tend towards infinity. I've read conflicting things about this, A, that that red shift WOULD NOT reach infinity in a finite time, and B, that...
  50. N

    Hawking Radiation inside a Black Hole?

    I've seen it said somewhere that an observer falling into a black hole doesn't notice anything qualitatively unique at the exact moment they cross the event horizon. Does this include Hawking radiation? That radiation is described as being emitted by the event horizon, so once the observer...
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