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> how did Einstein miss black holes? He didn't miss the possibility; he just convinced himself that this possibility could not actually be realized, and publis

by pdonis 5y ago

> how did Einstein miss black holes? He didn't miss the possibility; he just convinced himself that this possibility could not actually be realized, and published, IIRC, at least two papers giving his arguments for why. Unfortunately for him, both arguments were invalid. > Schwarzschild immediately saw the obvious No, he didn't. He did come up with the solution that is named after him, but he had no idea it described what we now call a black hole. The earliest recognition and acceptance of the fact that the Schwarzschild solution describes what we now call a black hole (though that term wasn't invented until several decades later) was in the classic paper by Oppenheimer and Snyder in 1939 that describes the gravitational collapse of an idealized exactly spherically symmetric body with zero pressure.

bmitc 5y ago
It's a little unfair to Schwarzschild. He discovered his solution, the first solution to Einstein's equations, while serving in WWI and actually before Einstein published his paper on general relativity. Schwarzschild died just a couple months after his paper describing the solution was published.
- pdonis 5y ago
  > It's a little unfair to Schwarzschild. How is telling the truth about what he did and did not do unfair? > He discovered his solution, the first solution to Einstein's equations, while serving in WWI Yes. > and actually before Einstein published his paper on general relativity. Before the official publication in 1916, yes. As I understand it, Einstein sent Schwarzschild a preprint and Schwarzschild based his work on that. > Schwarzschild died just a couple months after his paper describing the solution was published. Yes, and this was undoubtedly a tragedy. None of the above, however, contradicts what I said, which is that Schwarzschild did not realize that his solution described what we now call a black hole. The post I was responding to said Schwarzschild "saw the obvious", meaning saw a black hole in his solution. He didn't. Nobody did until the 1930s.
  - Zamicol 5y ago
    The Schwarzschild radius is the defining boundary of a black hole which Schwarzschild first calculated. A question worthy of asking is why did Schwarzschild beat Einstein in calculating the Schwarzschild radius first?
    - pdonis 5y ago
      > The Schwarzschild radius is the defining boundary of a black hole In our modern understanding, yes. > which Schwarzschild first calculated. He calculated that there was a constant that appeared in his metric, proportional to the mass, and with units of length. But he had no idea that this constant was related to the boundary of a black hole. Of course he didn't have much time to explore his solution further, since he was killed not long after sending his paper to Einstein. It's an interesting what if question to ask what he might have found if he had had years more to do physics. > why did Schwarzschild beat Einstein in calculating the Schwarzschild radius first? Einstein wasn't working on the specific solution for the case of a spherically symmetric vacuum surrounding a mass. He already knew that, to a first approximation, this solution would look like Newtonian gravity, and that the next order correction terms would explain the extra precession of Mercury's perihelion (which had been observed in the 19th century) and would predict gravitational redshift and the bending of light by the Sun (neither of which had yet been observed). Einstein was more interested in deriving the general form of the field equation than investigating further the specific properties of that particular solution. Whereas Schwarzschild focused on that solution.

by pdonis 5y ago

bmitc 5y ago

It's a little unfair to Schwarzschild. He discovered his solution, the first solution to Einstein's equations, while serving in WWI and actually before Einstein published his paper on general relativity. Schwarzschild died just a couple months after his paper describing the solution was published.

pdonis 5y ago
> It's a little unfair to Schwarzschild. How is telling the truth about what he did and did not do unfair? > He discovered his solution, the first solution to Einstein's equations, while serving in WWI Yes. > and actually before Einstein published his paper on general relativity. Before the official publication in 1916, yes. As I understand it, Einstein sent Schwarzschild a preprint and Schwarzschild based his work on that. > Schwarzschild died just a couple months after his paper describing the solution was published. Yes, and this was undoubtedly a tragedy. None of the above, however, contradicts what I said, which is that Schwarzschild did not realize that his solution described what we now call a black hole. The post I was responding to said Schwarzschild "saw the obvious", meaning saw a black hole in his solution. He didn't. Nobody did until the 1930s.
- Zamicol 5y ago
  The Schwarzschild radius is the defining boundary of a black hole which Schwarzschild first calculated. A question worthy of asking is why did Schwarzschild beat Einstein in calculating the Schwarzschild radius first?
  - pdonis 5y ago
    > The Schwarzschild radius is the defining boundary of a black hole In our modern understanding, yes. > which Schwarzschild first calculated. He calculated that there was a constant that appeared in his metric, proportional to the mass, and with units of length. But he had no idea that this constant was related to the boundary of a black hole. Of course he didn't have much time to explore his solution further, since he was killed not long after sending his paper to Einstein. It's an interesting what if question to ask what he might have found if he had had years more to do physics. > why did Schwarzschild beat Einstein in calculating the Schwarzschild radius first? Einstein wasn't working on the specific solution for the case of a spherically symmetric vacuum surrounding a mass. He already knew that, to a first approximation, this solution would look like Newtonian gravity, and that the next order correction terms would explain the extra precession of Mercury's perihelion (which had been observed in the 19th century) and would predict gravitational redshift and the bending of light by the Sun (neither of which had yet been observed). Einstein was more interested in deriving the general form of the field equation than investigating further the specific properties of that particular solution. Whereas Schwarzschild focused on that solution.