Focus on Nothing

by

by wj

There’s something to be said for us not losing track that there are great things happening in the world beyond politics. Like this one:
Image of a Black Hole

I admit that my first thought was :How can they take a picture of something that absorbs all light and reflects nothing?!?!?” But, of course, what they actually imaged was the shadow it causes in the glowing gas around it. Still, way cool.

36 thoughts on “Focus on Nothing”

  3. Not exactly a shadow, as the photons we’re detecting have orbited the black hole at a sufficient distance not to fall into it – the ones which have gone all the way around and escaped orbit in just the right direction to head towards us.
    So what we’re seeing is the photon disc (about 2.6 times the diameter of the event horizon, apparently).
    Not a very hospitable galaxy for life, I suspect.

  4. Not exactly a shadow, as the photons we’re detecting have orbited the black hole at a sufficient distance not to fall into it – the ones which have gone all the way around and escaped orbit in just the right direction to head towards us.
    So what we’re seeing is the photon disc (about 2.6 times the diameter of the event horizon, apparently).
    Not a very hospitable galaxy for life, I suspect.

  13. “2.6” might be the golden ratio squared though I can’t find it characterized as such.
    Not quite. The photon-capture radius of a non-rotating black hole is sqrt(27)/2 times its Schwarzschild radius. (paper)
    For rotating black holes it’s more complicated.

  14. “2.6” might be the golden ratio squared though I can’t find it characterized as such.
    Not quite. The photon-capture radius of a non-rotating black hole is sqrt(27)/2 times its Schwarzschild radius. (paper)
    For rotating black holes it’s more complicated.

  19. “Not a very hospitable galaxy for life, I suspect.”
    The supermassive black hole at the center of the Milky Way Galaxy sez ‘Hi!’.

  20. “Not a very hospitable galaxy for life, I suspect.”
    The supermassive black hole at the center of the Milky Way Galaxy sez ‘Hi!’.

  21. The photon-capture radius of a non-rotating black hole is sqrt(27)/2 times its Schwarzschild radius.
    Or (3*sqrt(3))/2.

  22. The photon-capture radius of a non-rotating black hole is sqrt(27)/2 times its Schwarzschild radius.
    Or (3*sqrt(3))/2.

  23. For the orbits of photons, Misner, Thorne & Wheeler equation 25.71 is the differential equation to solve.
    I have a rather simple Perl script that produces accurate numerical solutions, which alas, the comment box is too small to contain.

  24. For the orbits of photons, Misner, Thorne & Wheeler equation 25.71 is the differential equation to solve.
    I have a rather simple Perl script that produces accurate numerical solutions, which alas, the comment box is too small to contain.

  25. Snarki: Fermat quote? Or impressive truth (not obvious to us non-mathematicians)….

  26. Snarki: Fermat quote? Or impressive truth (not obvious to us non-mathematicians)….

  29. The program is a 1-2 hundred lines of Perl-written-in-the-style-of-FORTRAN, so not very useful to read. Accurate, yes. Validated against published calculations. Surprisingly simple individual calculations in each iteration. Fast. Write-only. Coyote ugly.
    Did the program for ‘light echos’ around a black hole; each echo has one more trip around the hole before escaping.

  30. The program is a 1-2 hundred lines of Perl-written-in-the-style-of-FORTRAN, so not very useful to read. Accurate, yes. Validated against published calculations. Surprisingly simple individual calculations in each iteration. Fast. Write-only. Coyote ugly.
    Did the program for ‘light echos’ around a black hole; each echo has one more trip around the hole before escaping.

  31. Perl-written-in-the-style-of-FORTRAN
    I’ve known programmers who wrote FORTRAN no matter what language they were using. 🙂

  32. Perl-written-in-the-style-of-FORTRAN
    I’ve known programmers who wrote FORTRAN no matter what language they were using. 🙂

  35. Yup. Let’s hope it’s an accident. They’re saying it may be connected to the renovation – on C4 News they’ve just reported that la fleche (the spire) has just collapsed.

  36. Yup. Let’s hope it’s an accident. They’re saying it may be connected to the renovation – on C4 News they’ve just reported that la fleche (the spire) has just collapsed.

Comments are closed.