Primordial black holes are theoretical mini black holes that were formed in the Big Bang. If they are around, they could pass right through our planet at tremendous speeds...and, as it turns out, that wouldn't be that big a deal.
These black holes would only be about the size of an atomic nucleus, but their mass would of course be far greater - in the most likely case, roughly the mass of an asteroid. Primordial black holes are sometimes put forward as a possible doomsday scenario, with one disproved fringe theory suggesting the 1908 Tunguska event was actually a black hole zipping through the Earth. So just how bad are these little black holes, really?
The answer, it seems, is no worse than a mild earthquake. As ScienceNOW reports, Princeton researchers have simulated the likely most common mass of these primordial black holes and found that these objects would take about a minute to make it through the Earth and back out again, with the only evidence of their passage a few mild tremors. As primordial black holes get bigger, the tremors of course also grow more violent, but such black holes are much, much rarer.
We likely don't experience any collisions with even the smallest primordial black holes much more than once very few million years - again, assuming they even exist. As for an impact on the scale of Tunguska - which, as bad as it was, was hardly a doomsday event - those would be multiple orders of magnitude rarer, meaning the chance that we have experienced one in the entire course of humanity's existence, let alone the last 150 years, is virtually nil.
Unfortunately, this also means the chances of scientists confirming the existence of a primordial black hole one way or the other in our lifetime - or indeed in the next hundred lifetimes - is also almost non-existent. But thanks to this paper, if such a tiny black hole does pass anywhere near Earth, at least we will know how to detect it. For more, check out the original paper over at arXiv.
Via ScienceNOW. Artist's conception of decidedly non-mini black hole via NASA/JPL-Caltech - click to expand for a closer look at it, because this is one seriously beautiful image.