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I was just curious what Richard Feynman thought of Stephen Hawking's Hawking Radiation. Feynman was one of the developers of quantum field theory and Hawking's work would have been cutting edge on the unification of gravity with quantum mechanics.

Feynman passed away I believe in 1988 but there would have been plenty of time for them to meet and discuss Hawking radiation since that concept was published around 1974. I'm not coming up with much on my research,maybe somebody else has better resources.

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    $\begingroup$ I looked in two biographies of Feynman that I have --- Genius. The Life and Science of Richard Feynman by James Gleick (1992) and The Beat of a Different Drum. The LIfe and Science of Richard Feynman by Jagdish Mehra (1994). Hawking is only mentioned in a couple of places in Gleick's book (according to the index), and nothing relevant to your question is mentioned in either place. Hawking is not mentioned at all in Mehra's book --- at least his name seems to be absent from both the name and subject indexes. $\endgroup$ – Dave L Renfro Jun 19 '18 at 15:55
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    $\begingroup$ From personal memory, no written sources, Feynman and Hawking met several times during the latter's visits, but I do not recall interactions between them. Feynman did not appear to be interested in Black Holes at the time. He was not even interested in Supergravity, while Hawking was, as per personal discussion remembered. $\endgroup$ – Cosmas Zachos Jun 20 '18 at 15:22
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I take that your primary goal is to know what Feynman thought of Hawking's work. While it is possible that they have met I would consider it unlikely given that Feynman mentioned several times how his attendance of the Chapel Hill conference (on general relativity) made such a bad impression on him that he never attended another conference on that theme, so they largely went around different social circles.

Yet, regarding Hawking radiation it is clear that he never understood it completely. If you search for "Feynman's last blackboard" you'll find the photograph of the blackboard in Feynman's Caltech Office at the time of his death. In the right upper corner there is a list of things "to learn", they are: Bethe Ansatz Probl., Kondo (dashed, so presumably he got that one), 2D Hall, accel. temp. and non-linear classical hydro.[If you have trouble finding it using your-favorite-search-engine look for the Reviews of Modern Physics about the Unruh Effect, authors are Matsas, Crispino and Higuchi]

Accel. Temp. is a clear reference to Acceleration Temperature, that is the Unruh Effect. While Hawking Radiation and Unruh Effect are different physical phenomena (that is, they have different causes), they are very closely related, both physically and in their mathematical derivation, therefore it seems unreasonable to think that he understood Hawking's work, and other related to quantum gravitation, since he did not understand the Unruh Effect, arguably the simplest example of related phenomena.

The other answer mentions stimulated emission by rotating black holes (sometimes people call it Zel'dovich Effect in the literature). By Hawkings own recollections, he first thought of Hawking radiation while visiting the USSR in the 1970s, and there Zel'dovich showed him that a electrically charged black hole would amplify electromagnetic waves. He (Hawking) then made the connection with stimulated and spontaneous emission, and back in the UK finished the calculations. [We'll, it's embarrassing but I cannot remember exactly where he wrote that, I'm not in my office for some time now. This version of the story is either in the book "300 years of gravitation" (Hawking was one of it's editors) or in Kip Thorne's "Black Holes and Time Warps". Sorry for giving no concrete reference, I would bet on Thorne's book right now, also because if Feynman showed the math to Kip Thorne's students then surely it will be mentioned in Thorne's recollection on the history of GR.]

Hope it helps to dig further references, but this is the extend of which I'm aware.

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    $\begingroup$ hell...you got the blackboard ..... you have exceeded more details than I though would ever be possible......kudos , I accept the answer $\endgroup$ – Sedumjoy Jun 19 '18 at 21:50
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    $\begingroup$ There's something about Zeldovich in chapter 7 of A brief history of time. $\endgroup$ – John Duffield Jun 21 '18 at 16:17
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Dunno if they ever met in person. There's an interesting video (one of several sites available) which states that Feynman came up with the "Hawking Radiation" theory well before Hawking did, but didn't publish.

A partial transcript (I cannot speak to its authenticity) from a blog :

In 1972 before Hawking came out with the Hawking radiation formula. Feynman was meeting with Kip Thorne's grad students, Bill Press, Saul Teukolsky & Lightman. They discussed a recent calculation of shining light on a rotating black hole and getting more energy out then in at expense of decreasing rotational energy of the hole. They all went back to Lightman's office. Feynman said: "Hey this is like stimulated emission. So he went to black board and did a A & B coefficient model and then when angular momentum J of the black hole J -> 0 there was still "A" spontaneous emission and it was the later Hawking formula! Well, let me admit that I don't quite understand how the formulae from stimulated emission are useful for deriving the "Hawking formula", whatever it is. It could be interesting to try to reconstruct Feynman's blackboard. A maid erased the board that night before Lightman and the others realized they should have written down what Feynman wrote. Not even Feynman thought it was important enough to write a paper about apparently.

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    $\begingroup$ This appears to be more of an interesting twist in a movie script (especially the part "a maid erased the board that night..."). Authenticity of the episode hinges on an satisfactory answer to how, when and why did "the others realized they should have written down..." The next day facing a blank board? But if it rested in their memory they could have written it down. If it didn't rested in their memory, how could they realize it "later", when Hawking published after some years? Moreover, if it appeared to be so trivial, why would it have stayed in their memory even if hazy for years? $\endgroup$ – Alecos Papadopoulos Jun 19 '18 at 17:23

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