The image belongs more to science fiction than to real life: a black hole, that beast of the cosmos capable of swallowing stars, crossing through a human body. But that scenario, as outlandish as it sounds, has just received some serious scientific analysis. Physicist Robert J. Scherrer, from Vanderbilt University, has published a study that evaluates what would happen if a very small and dense primordial black hole passed through a person.
The result: the probability of it happening is ridiculously low, but the effects, if it happens, would be catastrophic for whoever crosses it. Let’s go in parts. The first thing is to understand what a primordial black hole is.
When we think of black holes, we imagine immense stellar bodies, the result of the collapse of giant stars. But the theory allows for an alternative: the so-called primordial black holes (PBHs). These hypothetical objects could have formed in the early moments of the universe, when density and energy fluctuated violently. Unlike their stellar siblings, these PBHs could have much lower masses… although equally concentrated, and tiny diameters.
That is to say: the PBH could be, in size, microscopic, and yet carry an enormous mass sufficient to generate intense gravitational effects in its immediate environment. If what we are looking for is data, Scherrer has used a PBH model smaller than an atom (one thousandth, if we are looking for precision), but with a mass of 140,000 million tons.
Now comes the second question: how would its passage through the body affect us? Scherrer considers two main mechanisms of damage. The first is supersonic shock waves. If the black hole passes through the body at high speed, its passage would generate a shock wave, the effects of which would be comparable to those of a bullet. That wave would break tissues and cause massive destruction in the area.
The second scenario is that of gravitational tidal forces. A black hole exerts brutal but extremely localized gravity. Tidal forces (the gravitational difference between nearby points) They could be so intense that they tear cells, tissues, even organs. In delicate areas such as the brain, this differentiated stretching could destroy structures with lethal results.
And then comes the third and final question: does this mean that we are in permanent danger? No. Rather the other way around: that the threat exists only in theory. Estimates indicate that the density (i.e. how many of these PBHs would there be per volume) with Sufficient mass to be dangerous is so low that the probability of one passing through a human body is practically zero.
So… If it is never (statistically speaking) going to happen, why study it? Because it allows you to think the unthinkable and in doing so, delimit the plausible. This type of hypothesis has several objectives:
It helps define limits on the mass and density that primordial black holes should have to cause observable effects, whether on humans, planets or objects. That, in turn, allows certain mass ranges to be excluded as candidates for dark matter. It also forces us to refine astrophysical and cosmological models: If PBHs existed in abundance, they should leave detectable traces, for which there is no evidence so far.
The idea of a microscopic black hole passing through a human body has the dramatic power of science fiction, but also rigorous physical support if the calculations are adhered to. Scherrer’s study shows that it could cause instantaneous destructionthrough well-founded mechanisms. But it also shows that the probability of it happening is tiny.
This type of study reminds us of something fundamental: science lives on the frontier of knowledge, between what is observed and what is possible. Sometimes, imagining the extreme serves to better define what is real. And in this case, although The risk of a PBH passing through us is practically zero, exploring it helps us better understand the deep nature of the universe.