Einstein's theory, or the idea that gravity is matter warping space-time, has persisted for a hundred years as new astronomical discoveries have been made.
Researchers from the Event Horizon Telescope collaboration, the team that imaged the central black hole of the M87 galaxy last year, analyzed the black hole's "shadow."
Black holes don't cast shadows in the typical sense because they aren't solid objects that prevent light from passing through them.
Instead, black holes interact with light a little differently but create a similar effect. A black hole can pull light toward itself, and while light can't escape the inside of a black hole, it's possible for light to make a getaway in a region around the event horizon, or point of no return. This in-between space can look like a shadow.
Because black holes have such immense gravity, which curves space-time, it can actually act like magnifier that makes the black hole's shadow appear larger than it is.
"This is really just the beginning. We have now shown that it is possible to use an image of a black hole to test the theory of gravity", said Lia Medeiros, study coauthor and postdoctoral fellow at the Institute for Advanced Study in New Jersey. This test will be even more powerful once we image the black hole in the center of our own galaxy and in future EHT observations with additional telescopes that are being added to the array.