Thanks for your questions. I will try to answer below. Do not hesitate to come back to me if necessary.
Do black holes actually exist?
From the recent LIGO/Virgo observation, we have an indirect proof of their existence. The only explanation to the gravitational waves that have been generated by the merging of two black holes. No other object could explain this. This was the first evidence of a black hole.
I always thought black holes were voids of nothingness? I guess black holes are actually separate things that are made of of different forms of matter....interesting....
Black holes are very compact and very dense objects, They have a mass, a spin, etc... and they interact.
Fascinating, thank you so much for the responses. Really appreciate it :)
My pleasure :)
Well there is another evidence for the existence of black holes (here, the super-massive one at the center of our galaxy): If you observe the motion of stars nearby, you observe that they are in orbit around a dark point, and that this point must have a huge mass.
That study took years, but the observation is pretty clear:
Yes, you are totally right. I forgot about those pieces of evidence (less exciting than the GW ones :) ).