all the colours of the universe

[amovingtarget]

How to See a Black Hole: The Universe's Greatest Mystery watched 11 April

• Funny to think that no one has ever really seen one or can prove it exists when we're so used to thinking that they're real.

• Centre of our galaxy. A cluster of stars orbiting something so fast that it must have the mass of four million suns. Sagittarius A* black hole. 26,000 light years away from earth. "It would be the equivalent of trying to see an orange at the distance of the moon."

• Following Dr Sheperd Doeleman's plan to combine eight separate telescopes across the world to get a glimpse of the black hole, effectively building a telescope as big as a planet. I don't think you could have a cooler name than Event Horizon Telescope for the first picture of a black hole.

• Each telescope records the data onto hard drives and then the drives have to be taken to one place and plugged into a supercomputer. "It's a technical tour de force like we've never seen before." - Max Tegmark

• So how do you take a picture of something that eats light when the way we take pictures is by recording light? You take a picture of the accretion disk, which is interstellar gas burning as being pulled into the black hole, how cool is that.

• According to Einstein, mass curves spacetime, and if they don't see something circular, that would be the first time the theory of relativity would be wrong in a hundred years. This is the first time they might really be able to prove his biggest theories. Even Einstein didn't believe black holes could ever exist!

• Einstein said, matter just wouldn't allow itself to be crushed that much, enough to form a black hole, but over time scientists have theorised that black holes could be "the corpse of a giant star that's gone supernova". The resulting singularity has gravity so intense that it warps spacetime so much that nothing can escape, forming the black hole event horizon. The maths say that the point at the centre of the black hole has infinite density which, how the fuck do you get infinity? how do you measure it?

• They started the project at the beginning of 2017 and they had to work with the fact that there would be no way to see realtime results, so they had to do a kind of dress rehearsal to make sure they get it right. The telescope works by recording the black hole's radio emissions, the hard drive have to be specialised -- filed with helium to operate at high altitudes. Cloud cover, equipment failure... every single telescope needs to get the full reading or it might not work at all. The south pole is the best site -- "It more than doubles the resolution of the array" - Dan Marrone -- for the reading because it's pretty much permanently clear but it's also the most inaccessible, and inhospitable, and needs to be fitted with a custom mirror and tested as well.

• They had problems recording the test data but they managed and man, that's such a feeling when they managed to make it work. It was more than two years ago and I'm still so relieved and happy for them.

• The Event Horizon Telescope chose the hole at the centre of the galaxy Messier 87 for the portrait, because it's the one they can 'see' best so far.

• March 2017 and the test run data shows that the telescopes link up successfully but they still have to calculate for nature being nature. Hawaii has a lot of tectonic activity, and the ice sheet under the south pole telescope can move massively, and telescopes under the moon will be affected by its gravity "half a metre up and down every six hours". Incredible. Overheating hard drives are also a problem so they need special cooling set up, as is losing hard drives or physically damaging them even a little. They don't have an unlimited amount to use and they can't even make back ups.

• After ten years of planning, they have a ten day window for all these telescopes to get a picture of that black hole and they have to get five nights of data, nights where there are no clouds at any one of them and they have to choose their moment carefully. "If you make the wrong 'go' or 'no go' decision, you may have jeopardised your ability to image a black hole, and that's what consumes us when we're in that room." - Shep Doeleman.

• They have to work out precise timings as well, because the earth (or the rest of the universe) isn't going to hold still for the perfect picture. The telescopes need to receive data within a millionth of a millionth of a second of each other, holy shit. They need a hydrogen maser clock, one of the most accurate measure on earth, and it needs to be kept cool and -- I can't believe this -- the cooler on the device is broken so at the last minute, the only thing they can to is keep the door open on it to let the excess heat out because how are they gonna call an engineer out to the ass end of the earth Atacama desert.

• I didn't notice a date on the show for the final readings and I can't seem to find it online, but they were looking at both M87 and Sagittarius A*. They have to deal with long nights, high altitudes, stress, problems with the readings, weather changes, data corruption. And they won't even know if it's worked for months, five months minimum for them to even get the hard drives out of the south pole. I can't even imagine.

• Oh no, the put the data through the correlator and they find out one of the atomic clocks in Spain was fault and the readings are messed up! Luckily it's something they can fix. Then they have to try and piece together the image, like pixel jigsaw, and they don't have all the pixels(?) so first they're testing their algorithms on quasars because they know from existing data what that should look like.

• And then, they have the picture and it's so beautiful I could cry. "So we're seeing the very definition of this surface... where light is lost forever." - Shep Doeleman.

I also need to point out that I heard about the black hole image from Matt Mercer making a Critical Role reference, for maximum nerd. It doesn't get better than that.