Black holes, an explosion of which is thought by scientists to have created the big bang that created our world are super giant. Reportedly the smallest black hole is 3.8 times the mass of the sun, the largest being 78 billion miles in diameter, or 40% of our solar system.
Black holes are so called because they emit no light, are vacuums and contain what is described as dark matter, reportedly a mysterious substance connected to gravity. Conclusions of gravitational waves and ripples are reportedly arrived at by observing distant collisions of black holes and neutron stars which are massive, dying stars.
According to reports black holes are connected to time because the observer rate at which time passes in a black hole for a body or object depends on velocity, that is speed and direction. Spacetime, relative, means objects do not last long in space.