Now that gravitational waves have been directly observed, the next big goal in gravity physics is to better observe black holes. While there is lots of evidence showing black holes exist, we’d really like to observe them more directly.
The Event Horizon Telescope hopes to see the region around a black hole directly. Since the black hole itself doesn’t emit any light, what we hope to observe is the hot material close to the black hole. Because the closest material is relatively near the event horizon of a black hole, the light we see would be greatly distorted by gravity, causing its appearance to warp in shape and color. The science fiction movie Interstellar, for example, used computer simulations to create a simulated black hole showing some of these effects. But the black hole in Interstellar is an enhanced Hollywood version, and not quite what we’d actually observe.
A real black hole would look somewhat less dramatic, as seen in this video. Produced in part by some of my colleagues at RIT, the video shows the hard and soft x-rays emitted by the corona and accretion disk of a black hole, including the gravitational warping and Doppler shift caused by relativity. It gives us a good idea of what we expect to see near a black hole.