Scars left on Earth by a mini black hole

Could a mini black hole have crossed part of the Earth, leaving telltale traces of its presence in the places it passed?

The only black hole formation processes that seem to exist today in the universe are the death of a high-mass star and a sufficient increase in the mass of a very compact star, such as a neutron star, for example. for swallowing a lot of matter. However, it is believed that the exotic conditions prevailing in the universe shortly after the Big Bang (the colossal “explosion” with which it was born) could have allowed, long before the formation of the first stars and planets, the creation of numerous mini black holes. , which would have the size of an atom and the mass of a mountain. In the current universe, the primordial mini black holes that still exist would not absorb stars, but only parts of them.

A new study has delved into what signals such black holes would leave on the stars they encounter.

The study was carried out by Dejan Stojkovic, from the University at Buffalo (State University of New York), and De-Chang Dai, from Case Western Reserve University in Cleveland, Ohio, in the United States, both institutions.

If they exist, these mini-holes with such a small mass must be very difficult to detect, just as it is difficult to gravitationally detect a distant asteroid.

Artist’s recreation of primeval mini black holes. In reality, it would be extremely difficult for an accretion disk to form around any such holes, unlike the situation shown in the illustration. (Image: NASA)

But, according to Dejan Stojkovic and De-Chang Dai, it would be feasible with current technology to detect the traces left on stars by an interaction with a mini black hole.

The largest footprints would be asteroids, and other stars of modest mass, with their interiors abnormally hollow. The smallest traces would be microscopic tunnels, for example in everyday materials on Earth such as stone, glass and metal.

The study postulates that a primordial mini black hole trapped inside a large rocky object in the cosmos would consume its liquid core and leave it hollow. The black hole in the center of that star could escape from it if it were hit by an asteroid. After the departure of the minihole, what would remain of the star that housed it would be a hollow shell.

The study calculated how big a hollow asteroid could be without collapsing in on itself. By comparing the strength of natural materials such as granite and iron with the surface tension and surface density, the researchers calculated that such a hollow object could be no more than a tenth the diameter of the Earth. If it were larger, that hollow shell would collapse on itself.

These hollow objects could be detected with telescopes. Mass, and therefore density, can be determined by studying the orbit of an object. If the density of the object is too low for its size, this can be a good indication that it is hollow.

Alternatively, a primordial black hole flying fast enough through the cosmos would not become trapped in the star it collided with. It would pass through him like a knife through flan. This would mean that in solid materials it could excavate straight tunnels large enough to be visible with a microscope. Among those materials, there could be some right here on Earth.

This means that quite a few everyday objects around us could serve as detectors for the passage of mini black holes.

A large piece of metal or other material could serve as an effective black hole detector when monitored for the sudden appearance of these tunnels, although tunnels would be more likely to be found by searching for them in very old materials, from rocks several billion years old. old to buildings several centuries old, where such tunnels excavated at some time in the past could have been preserved.

If you’re worried about a primordial mini black hole passing through you, calm down.

For starters, the likelihood of a mini black hole passing through you at some point in your life is tiny. But even if it did happen, it wouldn’t be deadly. In fact, chances are you didn’t even realize it.

Unlike a rock, human tissue has little tension, so a mini black hole wouldn’t tear it apart. And although a mini black hole’s kinetic energy can be enormous, it is unable to release much of it during a collision because it moves so fast. “If a projectile moves through a medium at a speed greater than the speed of sound, the molecular structure of the medium does not have time to respond,” explains Stojkovic. “If we throw a stone against a window glass, it will most likely shatter the glass. On the other hand, if we shoot a bullet at the window glass with a gun, it is likely that the bullet will leave only a hole.”

The chances of finding traces left by mini black holes are small, but searching for them would not require many resources and the potential reward, the first evidence of a primordial black hole, would be immense, as Stojkovic argues.

The study is titled “Searching for small primordial black holes in planets, asteroids and here on Earth.” And it has been published in the academic journal Physics of the Dark Universe. (Fountain: NCYT by Amazings)