[advertising guy]

how in hell do they know there are 18 billion?

fuzzy math ?

[adorno]

how in hell do they know there are 18 billion?
Good questions. Also, why is the more "massive" black hole illustrated as a larger black cirlce and the smaller black hole as a smaller black circle. The way I understood black holes, all accretion goes into a singularity that is by all indications, smaller than an atom. So, shouldn't both black holes be illustrated as being the same size? Perhaps they need a different way of illustrating weight for celestial bodies.

[LibWhacker]

No, not fuzzy at all. There are non-fuzzy equations in physics that allow you to calculate the masses if you know the period, etc.