One of the key differences between galaxies with super massive black holes is whether or not the black holes are lit up, because they are basically bingeing on a lot of material in its surroundings.
Black holes are very exotic objects. Technically, a black hole puts a huge amount of mass inside of zero volume. So our understanding of the center of black holes doesn't make sense, which is a big clue to physicists that we don't have our physics quite right.
We have this interesting problem with black holes. What is a black hole? It is a region of space where you have mass that's confined to zero volume, which means that the density is infinitely large, which means we have no way of describing, really, what a black hole is!
How do you observe something you can't see? This is the basic question of somebody who's interested in finding and studying black holes. Because black holes are objects whose pull of gravity is so intense that nothing can escape it, not even light, so you can't see it directly.
My work indicated that if we consider smaller and smaller black holes, at some stage, the properties of black holes become indistinguishable from those of elementary particles.
My work on black holes was on the connection between black holes and elementary particles.
The size of the effect that we measured from the first event, the merging of two black holes, the actual size of the signal was about one thousandth the size of a proton, what it did to our apparatus.
When the signal reached LIGO from a collision of two stellar black holes that occurred 1.3 billion years ago, the 1,000-scientist-strong LIGO Scientific Collaboration was able to both identify the candidate event within minutes and perform the detailed analysis that convincingly demonstrated that gravitational waves exist.
Einstein got most of the things right about black holes. I'm not an expert, I must admit.
I once had an extraordinary experience with former prime minister Ted Heath. Both of his eyes, including the whites, turned jet black, and I seemed to be looking into two black holes.
