The Mischievous Nature of Primordial Black Holes

Primordial black holes are strange little critters. They’re not the product of a massive star recently gone supernova and they’re not as exotic as a wormhole, tunnelling a gateway into another dimension. They are very, very old remnants of the very beginning of our Universe. Much like the foamy bubbles left over from washing the dishes, a few bubbles stubbornly hang around on the side of the sink for an hour or so after the water has long gone. Primordial black holes (or PBHs for short) are just that, the leftovers from the very energetic (and very bubbly) Big Bang 14 billion years ago…

…but they’re not done causing trouble quite yet…

Due to the massive energies generated at the beginning of our Universe, countless black holes are thought to have been created. However, small black holes are not expected to live very long. As black holes are theorized to radiate energy, they will also lose mass (according to Stephen Hawking’s theory, Hawking Radiation), small black holes will therefore fizz out of existence very rapidly. In a well known 1975 publication by Hawking, he estimates the minimum size a black hole must be to survive until present day. The PBH would have to be at least 10¹²kg (that’s 1,000,000,000,000 kg) in mass when it is created. 10¹²kg is actually quite small in cosmic standards – Earth has a mass of 6×10²⁴kg – so we are talking about the size of a small mountain.

But, these antique cosmic leftovers are theorized to be knocking around space right now, and there might be quite a lot of them. Some scientists predict that most of the Universes dark matter is held in PBHs, so there is likely to be a massive density of them still floating around.

But are they dangerous? Well, as I’ve covered in articles on the Universe Today, they might punch small radioactive holes on the Earth, but more shockingly, they could scatter asteroids out of their predicted orbits creating massive meteorites, wiping out our planet! As if we had enough to worry about…