The next time you go jetting off into the universe, watch out for black holes — there are lots of them. A recent study calculated that there are 40 billion billion of them — a four followed by 19 zeroes.

The study was looking at the most common type of black hole — ones that are born from the death of a massive star. Such black holes range from a few times the mass of the Sun to more than a hundred times the Sun’s mass. Astronomers have cataloged several thousand of them, mainly in our home galaxy, the Milky Way.

Scientists in Italy simulated conditions in stars and galaxies throughout the universe. In particular, they looked at the rate at which galaxies give birth to stars, the masses of the stars, and the composition of the stars — especially the ratio of elements other than hydrogen and helium. And they considered how many black holes are born in binary systems — pairs of stars bound by their gravity.

And they found that the universe must contain many more black holes than suggested by earlier studies. In fact, this class of black holes could account for up to one percent of all the normal matter in the universe — a hundred times more than found in the giant black holes at the hearts of galaxies.

The universe is big, so there’s a lot of elbow room between black holes. But since a black hole doesn’t produce any energy on its own, one can sneak up on you — especially with 40 billion billion of them lurking in the cosmos.
 

Script by Damond Benningfield

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