3 ms·
SciShow Space recently did an episode on Brown Dwarfs. They suggest that there might be so many brown dwarfs (which are hard to see), that they could account fo
by Tharkun 7y ago
SciShow Space recently did an episode on Brown Dwarfs. They suggest that there might be so many brown dwarfs (which are hard to see), that they could account for a large portion of the "missing" mass.
And there's a theory that says there are small "primordial" black holes all over the place, which are also hard to detect individually, but together could also account for a large part of the missing mass.
Perhaps invisible brown dwarfs and invisible black holes are an easier pill to swallow than mysterious dark masses/energies?
- ymolodtsov 7y agoThe primordial black holes theory is much more of a theory than the dark matter. The corridor for their existence is getting smaller and smaller and they can’t really help establish the current large scale structure of the Universe (while cold dark matter can).
- DCKing 7y agoThis is the MACHO hypothesis, which seems to have fallen somewhat out of favor since we can measure this to some extent and we can't find anything close to the required mass [1]. Although it is likely there is unaccounted regular matter, I think it is considered unlikely that this will account for the 85% of "missing matter" that we need, not in its entirety and likely not for a significant part of that either. You will need a humongous amount of brown dwarfs to compete with the regular stars and known (supermassive) black holes that are already in the known 15%. [1]: https://en.wikipedia.org/wiki/Massive_compact_halo_object https://en.wikipedia.org/wiki/Massive_compact_halo_object "A survey of gravitational lensing effects in the direction of the Small Magellanic Cloud and Large Magellanic Cloud did not detect the number and type of lensing events expected if brown dwarfs made up a significant fraction of dark matter."