4 ms·
No. Dark matter is spread relatively homogeneously so you would need very small back holes, and those would be visible or wouldn't have existed this long. Bar
by hwillis 9y ago
No. Dark matter is spread relatively homogeneously so you would need very small back holes, and those would be visible or wouldn't have existed this long. Baryon acoustic oscillations also limit how much normal matter we can have, and they say there has to be a great deal of non-baryonic matter.
- Sir_Cmpwn 9y agoI think you only grok half the story here. You're correct - black holes are not a popular candidate for dark matter, for reasons you described. But this article is not about candidates for dark matter, it's about removing dark matter from the equation entirely. If I understand correctly, black holes here are given as an explanation for isolated examples of strange gravitational lensing effects.
- hwillis 9y agoThere aren't isolated examples of strange gravitational lensing. The lensing being discussed occurs at the scales of galaxies and clusters of galaxies, so you need an incredible number of tiny black holes, brown stars, or other MACHOs.
- Sir_Cmpwn 9y agoYou're right, gravitational lensing anomolies explained by dark matter are more commonplace than I had thought.