Originally shared by Ethan Siegel
“The most recent LIGO event made me wonder how numerous black holes are, and that made me wonder what the sky would look like if we could see them (and, for clarity, see only black holes)… what is the spatial and intensity distribution of black holes compared the distribution of visible stars?”
For the third time since it began taking data, the LIGO collaboration discovered direct evidence for merging black holes in the Universe. There’s an incredible amount we’ve learned about black holes and where they’re located, however, and very little of it comes from gravitational waves. Instead, we know how black holes are made, where their progenitors are and were located, and how they’re likely to be distributed today. If we put this picture all together, we can come up with a numerical estimate for how many are likely to be present in our galaxy, along with where they’re expected to be concentrated. It’s an incredible picture!
Just a few decades ago, we weren’t sure black holes even existed; now we think we know where millions ought to be in every galaxy. Come get the remarkable story on this week’s Ask Ethan!