Primordial Black Holes

My friend Michael G. Burk sent me an interesting question about this article this morning. As is often the case with his inquires, it really got me thinking. I'm sharing my response to him.

Michael, you always have the most thought provoking questions.

I did a quick calculation to see if these smaller black holes would have evaporated given the age of the universe. Bottom line, they should still be floating around. I can't think of any reason they wouldn't have been created at some point of the big bang. If you drop a rock (or a sugar cube) into a cup of coffee and look at the splash droplet pattern, you'll see that many of the droplets coalesce into larger droplets...but not all of them.

The real question to me is when in the course of the big bang expansion, they would have been created. If its early then they would have expanded too. This means a physically large low density object that never-the-less is a black hole. i.e. Light doesn't escape. We could be living in a large ball of swiss cheese like space with voids. This is an interesting concept that will require deeper thought to work out the consequences. But my guts says the lower density means the transition between inside and out would be much smoother. This could be consistent with both dark matter and dark energy if these primordial black holes are still undergoing inflation (linear time breaks down near black holes. So continuing big bang era inflation is still on the table).

Alternatively, without this expansion, each of these smaller one stellar black holes would have a radius of about 2 miles. We'd never see them from Earth via lensing of star fields behind them. Collision detection via LIGO might be our best hope.

Looking for these big bang generated low mass black holes and in particular their frequency and size distribution provides an interesting probes into the evolution of the earliest periods of the big bang itself.

I think Spock says it best. Fascinating.

-Peter