Evidence of a black hole visiting Earth may be hiding in your house

Bebe!

Astronomers suspect that in the first second after the formation of the universe, the first black holes appeared. These tiny yet dense objects — think of particles the size of an atom that carry the weight of a mountain — are called “primordial black holes.” But there is a problem: there is still no evidence that they ever existed.

Now, scientists have proposed a novel idea: Perhaps the evidence is right in front of us, here on Earth.

In a new study published in the journal The Physics of the Dark Universeresearchers concluded that ancient objects could have left visible evidence in invisible tunnels, or even in hollow objects beyond our planet such as asteroids. Although the chance of finding small tunnels on Earth is small, they may exist in places around us, such as stone, glass, and metal in buildings – especially old buildings.

“The hardest thing is to see what’s right in front of your nose,” Dejan Stojkovic, a professor of physics at the University of Buffalo who co-authored the study, told Mashable.

Black holes are almost unimaginably dense. If the Earth were (hypothetically) crushed into a black hole, it would be less than an inch in diameter. Today, many black holes form following the collapse of massive objects such as stars, especially after violent supernova explosions. The objects themselves are rare: There are about 100 million black holes orbiting our Milky Way Galaxy alone.

But the search for the first black holes in space has been fruitless. Although astronomers can see supermassive black holes with telescopes – because these objects accumulate a large amount of rapidly rotating material around them that emits a lot of energy – the first black holes are too small to accumulate such material. In addition, black holes are believed to emit a form of energy called Hawking radiation, which should be more powerful than small black holes, but that has not yet been observed. However, physicists say they must be there.

“Direct observational evidence for small black holes is still lacking, but according to our theories of the early universe, they should be produced normally without the use of any external physics,” Stojkovic said.

“The most difficult thing is to see what is standing in front of your nose.”

So Stojkovic proposed the unique idea of ​​using a microscope to look at the tiny tunnels on Earth, created by primordial, albeit powerful, black holes. (They would leave holes like a bullet running through a glass wall.) Looking at old objects offers the best opportunities, simply because such objects have been around for years and have had a greater chance of hitting a black hole. It’s also much cheaper to search for tunnels than to build a new, more sensitive detector, especially in the field of science where funding is tight and intensely competitive – even at NASA.

An alleyway in Fitzrovia, London.
Credit: Alexander Spatari / Getty Images

“Exploring old objects in small tunnels should be only a fraction of the cost of building a dedicated astrophysical detector. [which usually costs millions and even billions of dollars],” explained Stojkovic. “Any place on Earth is equally likely to be hit by a small black hole.”

The chances of finding a tunnel are “extremely small,” he noted, but so is the reality of manipulating for evidence left behind by these ancient, mysterious, and tiny particles. Stojkovic noted that physicists are also hunting for extremely rare “magnetic monopoles” — another hypothetical particle — with expensive detectors. Of course, it has proven difficult to find a magnetic monopole, but the scientific benefit can be great.

As exciting as it would be to find a tiny black hole tunnel on our planet, researchers also suggest looking elsewhere in our solar system. Specifically, in very small objects such as the moon or an asteroid with a liquid core (Jupiter’s moon Ganymede, for example, has a liquid core). A primordial black hole running through space would impact such an object, use its gravitational pull to sink in, and eventually, after escaping, leave behind an empty crust.

Lifetimes of black holes of different sizes. The first black hole the size of Mt. Everest could be 1 billion times older than the current age of the universe, says NASA. (The universe is about 13.8 billion years old.)
Credit: NASA

Such a curved object, the researchers calculated, could not be larger than one-tenth the diameter of Earth (about 400 miles) or it would collapse. Most importantly, telescopes can reveal the motion and size of an object. “If the density of an object is very low compared to its size, that is a good indication that it is empty,” Stojkovic said separately, in a university statement.

These are really new ideas. But the unsuccessful search for black holes may require negative thinking. I asked Stojkovic if anyone had ever tried to look at these small tunnels on Earth.

“Not that we know,” he said. “Maybe no one ever thought of it.”