Shep Doeleman Turned the Entire Earth Into a Telescope to Photograph a Black Hole
How Do You Take a Picture of a Black Hole?
Black holes are invisible by definition, so how did 250 researchers capture one on camera? Harvard astrophysicist Shep Doeleman explains to Janna Levin how he linked radio telescopes across the globe into the Event Horizon Telescope, producing the first image of the supermassive black hole in M87 and the one at the heart of our own galaxy. He describes the decades of collaboration behind the feat and why movies of black holes could arrive by the early 2030s.
Seeing is believing in a certain way. You can theorize something, but actually seeing it confers a reality on things that you don't get otherwise.
- myrmidon
What I find really interesting is that black holes don't really "require" infinite density; the mass density inside the event horizon never exceeds neutron star levels, and becomes in fact lower the heavier the black hole gets (=> event horizon enclosed volume grows faster than mass).
- lopsotronic
Easy. Space isn't empty.
Due to the insane distortion of "space"[1], every spare molecule in the vicinity is going to be lighting up at the speed of $E = mc^2$ . Which tends to be real visible. Black holes power some of the brightest things in the universe - light so powerful that it sometimes has its own gravity.
A tame black hole is possibly the least fussy high-efficiency furnace imagineable. Of course, "tame black hole" possibly . . . isn't.
[1] Whatever that happens to be, either bouncy rubber sheet or emergent property from deeper Hilbert Spaces or something beyond our imaginations. Or something that's just an illusion, an artifact of our specific perspective from our little spot in existence, like a rainbow.
- tilt_error
Well, for starters you need a reasonably long exposure time.
- rustyhancock
One of the most remarkable aspects of physics is that Newtonian gravity calculations are quite spot on for all the parts of black holes layfolk consider important.
1. Both predict the same critical radius, now called the Schwarzschild radius.
2. Both predict a central singularity with formally infinite density in idealised collapse.
3. Both predict exactly the same finite time to fall into the singularity under equivalent idealised conditions.
4. Both give the same equation for radial free fall, using different definitions of time.
What GR added was meaning to these things (and of course precise calculations outside of very idealised scenarios and symmetric conditions).
- JohnKemeny
Is it just me, or could they have added a, say, picture of a black hole?