The Universe Could Contain 40 Billion Billions of Black Holes

Scientists at the International School for Advanced Studies in Trieste (SISSA) have found that there are 40 billion billions (i.e., 4 followed by 19 zeros) stellar-mass black holes in the universe. This is about 1% of all ordinary matter in the universe observed by humans, EurekAlert reports.

To calculate stellar-mass black holes, the scientists calculated the rate at which they were formed. The researchers compared their calculations with gravitational wave data.