In the early universe, when the density was much thicker and stars where forming and exploding with enough regularity to form all the heavy metals we see today, why didn't it fill the universe with a lot more black holes than we have found so far?
John W
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Perhaps there are, one of the possible theories for dark matter is that they are MACHO's ( Massive Halo Objects ), in other words black holes. Black holes tend to be awfully dark and difficult to detect when something isn't falling into them.
Drabe
Very high mass stars are what create black holes. High mass stars are responsible for Supernovae. Stars have to be a certain mass once they are white dwarfs to explode. Most stars never do these things. Larger stars are more rare, and in the early universe they weren't really as present, as there were less stars. And regardless, there are plenty of black holes supposed to exist, based on statistics and all that. Hope this helps
Ray;mond
Why do you think we should find black holes which are several solar mass, unless they are close enough to perturb our planets significantly with their gravity. Possibly our galaxy has more black holes than visible stars. possibly billions of black holes orbit beyond the boundary of bright stars which marks the edge of our galaxy.
On the other hand, perhaps O, B, and A stars were rather rare the first billion years, so lots of quark stars, neutron stars and white dwarf stars were formed instead of black holes. These are also difficult to detect unless they are quite close = less than 1000 light years. Neil
Anonymous
It's based solely on the star (or star system) that causes it. Most average stars (including our own) will expand into a red giant, then into a dwarf. The very top <1% of stars are large enough and contain enough mass for a supernova. This supernova, given it has enough mass (another minority figure), then starts to reconvene on the original spot. The acceleration and gravitational mass condenses the matter inside to a very minutely small fraction to its star's original mass. It requires a very massive star to supernova, and then a very massive supernova; therefore, it's sheerly because >99.5% of stars aren't massive enough.
Bob D1
("Why aren't there more black holes?")
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I'm not an astronomer or cosmologist, but here's what I think:
There probably are many supermassive black holes out there that haven't been located just yet. However, that would not account for the dark matter. There's simply way too much evidence for the existence of real dark matter around galaxies and clusters of galaxies. As I understand it, gravitational lensing help cosmologists detect the gravity effects of dark matter. And more recently, something called dark matter mapping or dark matter clumping has been put into use to map clumps of dark matter around galaxies.
See: NASA - Hubble Maps the Cosmic Web of 'Clumpy' Dark Matter in 3-D ...
http://www.nasa.gov/mission_pages/hubble/news/clumpy_darkmatter.html
See: New 3-D Map of Dark Matter Reveals Cosmic Scaffolding
http://phys.org/news87400827.html
See: 3D Dark Matter Map based on COSMOS data
http://www.youtube.com/watch?v=qssFEr3N5dI
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