Topic: black hole
Kenny Lau (Apr 11 2019 at 02:05):
can we prove that the picture we saw yesterday is that of a black hole?
Kevin Buzzard (Apr 11 2019 at 03:18):
I'm not even sure we can prove that anyone saw anything
Kenny Lau (Apr 11 2019 at 07:21):
maybe we can prove that 1/u+1/v=1/f
Keeley Hoek (Apr 11 2019 at 07:47):
(I could just google this, but) is gravitational lensing even the same as the optical kind?
Mario Carneiro (Apr 11 2019 at 08:06):
Mario Carneiro (Apr 11 2019 at 08:07):
optical lensing happens because the speed of light is slower in a medium, and gravitational lensing happens because space isn't flat
Scott Morrison (Apr 11 2019 at 08:22):
Media aren’t “optically flat”?
Mario Carneiro (Apr 11 2019 at 08:44):
I see the resemblance, but I would still argue that they are really different. As another analogy, with gravitational lensing the light goes straight the whole time, and comes out going a different direction somehow. In the material case you can locally "see" the distortion at a medium boundary or change in refraction index
Mario Carneiro (Apr 11 2019 at 08:46):
Of course I don't need to explain to a room of mathematicians the weird things that "straight lines" can do on curved manifolds, even when there is no curvature (e.g. flat torus)
Last updated: May 10 2021 at 08:14 UTC