Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Were Hawking radiation and singularity thm controversial?

  1. Dec 1, 2014 #1


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    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. Hawking's 1965 PhD thesis was a proof of the Hawking singularity theorem, which shows that under certain assumptions, we can retrodict a singularity at the big bang. This was depicted in the film as if it were a big surprise in 1965. Was it?

    I would have imagined that ca. 1965 the hot big bang was a popular cosmological model. BBN was already fairly old (Alpher-Bethe-Gamow was 1948), and Penzias-Wilson was 1965 (don't know if it was before or after Hawking defended his thesis, or whether its significance was rapidly understood by the community). If one leaned toward big bang rather than steady state, there would have been two obvious possibilities as to the interpretation of t=0: (A) the singularity in the Friedmann equations is unphysical, or (B) it's physical. I can imagine solid reasons for taking A to be the more likely possibility, since experience with physical systems outside of GR would suggest that generic conditions do not lead to a pointlike convergence of trajectories. But did people actually consider B so unlikely that it would really surprise them to have it proved for non-generic final conditions, in a realistic model? If people had already understood and accepted the Penrose singularity theorem, the Hawking one would seem pretty easy to accept -- although of course it is disturbing philosophically to have a singularity that's not hidden behind a horizon.

    2. Hawking radiation appears to date to about 1974, and WP says that the idea was suggested to Hawking by Zeldovich and Starobinsky. The movie depicts Hawking proposing black hole evaporation at a public lecture at Cambridge, and during the Q&A session afterwards, they have a British physicist protesting that it was nonsense and storming out, along with several others, but then a foreigner (Russian? Italian?) stands up, introduces himself, and says that "this little guy" has figured out something important.

    Would black hole evaporation really have gone so strongly against entrenched ideas in 1974? After all, even the term "black hole" only dates back to 1964, and the one-way membrane interpretation of the event horizon to 1958 (Finkelstein and Kruskal). It would surprise me if there had been enough time by 1974 for people to have come to believe so strongly that black holes must be permanent and black, even with the introduction of quantum effects. Is this resistance to Hawking radiation historically real, or is it just a Hollywood dramatization?
    Last edited: Dec 1, 2014
  2. jcsd
  3. Dec 1, 2014 #2


    Staff: Mentor

    This suggestion is probably way out there but could you write a letter to Prof Kip Thorne or Prof Susskind asking about their remembrances of Hawking's paper on the scientific community at the time? This is the historians approach to these things when living witnesses to seminal events are available.
  4. Dec 1, 2014 #3

    George Jones

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I don't think that it was a huge surprise for relativists. Penrose previously had proved a singularity theorem for non-spherical stellar collapse, and this was a huge surprise, as his proof used point-set topology. This gave Hawking the idea of trying to use Penrose's methods to prove a singularity for something expanding outward.

    From Hawking's recent short autobiography "My Brief History"

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook