Question: Do you think there are any black dwarfs in the universe? if so what uses could it have in developing our understanding of the universe?

Sam Lawrence answered on 21 Nov 2019:

Good question. Black dwarfs are formed by white dwarfs cooling for a long period of time such that they do not emit any radiation, including light. Currently scientists believe that there are not any black dwarfs in the Universe. This is because the length of time taken for a white dwarf to cool into a black dwarf is longer than the age of the Universe. In other words, there hasn’t been enough time in the Universe for black dwarfs to be created. If we do in fact find a black dwarf then this would have a significant effect on our understanding of the Universe: either our estimation of the age of the Universe (13.7 billion years) is incorrect, or our theories about how black dwarfs form are wrong. If there are black dwarfs out there, that we cannot see, we would need to account for their mass when we are trying to explain the Universe. Theoretically, if there were enough black dwarfs that we couldn’t see, this would slow the acceleration of the Universe.