Evidence of primordial black holes may be hiding in everyday objects on Earth

Primordial black holes (PBHs) are fascinating relics of the early universe. Formed during the Big Bang's chaotic moments, these black holes are theorized to have mass ranging from a mountain’s worth compressed into the size of an atom to much smaller quantities.

PBHs are unlike their stellar counterparts, which form from collapsing massive stars. Instead, they result from areas of denser space that collapsed under their own gravity.

For decades, PBHs have been proposed as candidates for dark matter, the mysterious substance that accounts for 85% of the universe's mass. Despite their theoretical significance, no PBHs have been conclusively observed.

However, recent research presents innovative approaches to identify their elusive signatures, suggesting they could leave detectable marks on planets, asteroids, and even materials on Earth.

Theoretical work led by Dejan Stojkovic, PhD, at the University at Buffalo, and De-Chang Dai, PhD, of National Dong Hwa University, introduces two compelling hypotheses about PBHs. Published in Physics of the Dark Universe, the study explores how PBHs might interact with celestial and terrestrial objects.

If a PBH becomes trapped inside a planet or asteroid with a liquid core, it could slowly consume the core material. This process would leave a hollow shell supported by its solid outer layer. The hollow object might remain stable, provided the material’s strength prevents it from collapsing under its own tension. The researchers calculated that such hollow objects could exist but would be no larger than one-tenth the size of Earth.

“We can detect these hollow objects by studying their orbits,” Stojkovic explains. “If an object’s density is too low for its size, that’s a strong indication it’s hollow.”

Alternatively, if a PBH passes through a solid object without a liquid core, it could leave behind a narrow, straight tunnel. These tunnels would be minute, potentially only a micron wide, and could persist for millions or even billions of years.

The researchers suggest that large slabs of metal or ancient rock could serve as detectors, monitored for the sudden appearance of these microscopic tunnels.

The probability of a PBH passing through a boulder in its billion-year existence is estimated to be minuscule—around 0.000001—but the cost of searching for such signs is minimal compared to the potential discovery.

The study also calculates the stability of hollow planetoids formed by PBHs. Comparing the tension and density of natural materials like granite and iron with the theoretical models, the researchers determined that any hollow object larger than a tenth of Earth’s size would likely collapse. Thus, PBHs may preferentially interact with smaller celestial bodies, such as minor planets and asteroids.

A PBH's journey through Earth or other materials would be similarly undetectable by direct experience. The immense speed and density of these objects prevent them from releasing significant energy during such interactions.

Human tissue, for example, would not be torn apart by a PBH due to its rapid movement, which doesn’t allow molecular structures to react.

“If a projectile moves faster than the speed of sound in a medium, the medium’s molecular structure doesn’t have time to respond,” Stojkovic explains. “It’s like the difference between throwing a rock at a window, which shatters, and shooting a bullet, which leaves a hole.”

The implications of this research extend beyond detecting PBHs. If dark matter is indeed composed of PBHs, their interactions could provide answers to one of the most enduring mysteries in physics. Stojkovic emphasizes the importance of pursuing unconventional approaches in such investigations.

Existing models of physics, from general relativity to quantum mechanics, are over a century old and have yet to solve the puzzle of dark matter.

“The smartest people on the planet have been working on these problems for 80 years and haven’t solved them,” Stojkovic says. “We don’t need a straightforward extension of existing models. We probably need a completely new framework altogether.”

While the likelihood of directly observing a PBH is low, the potential payoff is enormous. These studies open new doors for exploring the invisible forces shaping the universe, proving that thinking outside the box remains vital in scientific discovery.

Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.

Like these kind of feel good stories? Get The Brighter Side of News' newsletter.