I have been having a ten year love affair with black holes. These are some of the most mysterious objects in the galaxy -- we can't actually see them as they don't emit or reflect any kind of light so we study them by looking at their influence on the material around them. But what are they exactly and how do they work? For years we weren't actually sure if there were black holes at the center of most galaxies or if it was just a heck of a lot of stars exerting a large gravitational influence. And yet, just a few weeks ago, scientists managed for the first time to image the event horizon of a black hole in the galaxy known as M87. Some liken it to taking a picture of an orange on the moon from here on earth. If we weren't absolutely certain before that these objects existed-- well we are now.
The image produced was not of the black hole itself but of the shadow it casts on the material (gas, dust etc.) right next to the event horizon of the black hole. The event horizon of a black hole is the point at which the black hole's gravity becomes so strong that only something moving faster than the speed of light (and we do not seriously think any such particles exist in current theories) would be able to escape. Thus, we cannot see any part of the black hole smaller than the event horizon. What's beyond that? Black holes are insane wells of gravity so the center of a black hole is actual a point of infinite gravity -- sometimes truth really is stranger than fiction. Black holes are these weird and complicated phenomena-- when they first emerged as a consequence of Einstein's theory of general relativity, Einstein remarked that he didn't think they could actually exist though they were allowed to mathematically. Who knew we would one day create an image of one in another galaxy?
For me, as a scientist, one of the most amazing things about this discovery was the sheer amount of effort that went in to it. Over two hundred scientists are involved in the work of the Event Horizon Telescope, the collaboration that made this observation. Normally, we observe our targets with a single telescope but this image required such precision that the data from 8 different telescopes was required!! So astronomers travelled to all eight telescopes (one of which is at the south pole) and waited until the weather was good enough at all the sites to be able to observe simultaneously. So the weather needed to be good in Spain, Antartica and Chile (as well as the other sites) at the same time for this observation to happen. Then, there is so much data collected, apparently equivalent to a lifetime of selfies from 40 000 people, that instead of sending it to one place via the internet to be analyzed, each astronomer had to fly a physical hardrive with the data back to a single location. Finally, in order to make sure they were absolutely sure they were seeing what they expected, the Event Horizon Telescope had several groups of scientists run their algorithms to generate a picture of the event horizon individually so that they could check that they matched up. This way, one team couldn't get a false positive and influence the results of all the other teams. It's like if you tell your friends a cloud looks like a duck and even if I used to think it looked like a rabbit now all I can see is a duck. In the end, the final image is one of the greatest scientific accomplishments of this decade, if not even longer. It almost looks too much like we would expect so some scientists are looking at the wiggle room between our predictions and the image produced to make room for evidence of previously undiscovered physics.
I think this also offers further proof that astronomy has truly become a global endeavour. I have been a part of large collaborations that span the world and allow us to do absolutely incredible science such as the Sloan Digital Sky Survey. As we continue to push the boundaries of what is possible it is going to require that we continue to band together to accomplish our scientific goals. Big ideas require big collaborations. While certainly some of our theories may come from a lone genius using a pad of paper and a pen, the increasingly complex nature of the questions we are trying to answer and the data we are collecting is going to make this more and more unlikely. Building something as sophisticated as the Large Hadron Collider, or designing an observing campaign that images almost the entire sky every three days like the Large Synoptic Survey Telescope is not a one person job or a ten person job. It will require huge collaborations and the next generation of astronomers must be willing to be collaborative workers. This may require new models in academia-- hiring mountains of grad students to do the work and then allowing them to leave the field because their are not enough full time jobs seems less than ideal at best and exploitive at worst but I have no doubt our profession is up to the task.