How black holes are like dams


Black holes are like dams, according to Tess Taylor’s review of Caleb Scharf’s book on black holes:

On earth, in a dam, there is pressure on one side and a lack of pressure on the other. Water forced through spillways, driven by gravity, generates enormous energy that we harvest as electricity. In a black hole, there is the universe on one side and a void on the other. And as stars and particles rush towards black holes, they pick up speed, sloshing in much the same way water does heading towards a dam or drain. Just as sloshing water represents lost energy we hear converted to gurgling sound waves, stars and gasses rushing towards the brink of a cosmic drain lose particles that can be “seen” translated into other forms of energy. The edges of black holes are thus always spewing matter, a kind of cosmic splatter paint. Although things pulled towards black holes are mostly swallowed, over time the sloshing of nearly swallowed stars spews the universe with a mess of Jackson Pollock-like cosmic goo.

This dissolving star glop, Scharf wants to let us know, is actually the universe’s generative mess. The things that splatter on the edges of black holes can themselves become new stars, or, can float as gasses that rearrange the galaxies they are in, or even the planets near them. The very fact of life on earth is certainly a gift of the random seepage of the right elements at the right time — a happy mix of carbon and nitrogen and oxygen, a little iron, a smidgen of gold. Our planet as we know it is the gift of imploded stars.