Hard to find black holes

Historian: Astrophysicists now think that there are huge numbers of black holes in our home galaxy and throughout the universe. The video linked to below is part of the evidence.

Physicist: In the video linked to below there is information in the upper right telling us what we are seeing which might be a simulation or an observation at one of the many ranges of wavelengths of light.

Finding a hard to find black hole [link]