Question: what are black holes?

Connor Macrae answered on 21 Jun 2015:

Black holes are the remnants of the most massive stars. After exploding as a supernova, the cores of massive stars are compressed to form an object so dense that not even light can escape the gravitational pull of it – this is then called a black hole. The physics behind how material behaves at such densities is still not understood, and it has been found that at the centre of almost all galaxies is a super-massive black hole!