If dark matter consists of a plethora of primordial black holes, then their gravitational lensing — magnifying and brightening distant objects — should be detectable. Physicists analyzed 740 known supernovas to find the handful that should have been magnified and brightened by black holes, and found none. This puts a strong upper limit, 40, on the percent of dark matter that can consist of black holes, and suggests that none of it is.
Black holes ruled out as universe’s missing dark matter
If dark matter consists of a plethora of primordial black holes, then their gravitational lensing -- magnifying and brightening distant objects -- should be detectable. Physicists analyzed 740 known s..
