Scientists may have finally solved the problem of 'missing' black holes in the universe

Lina PortmanMay 31, 2024

0 3 minutes read

The early universe contained far fewer miniatures black holes than previously thought, making the origins of our cosmos' missing matter even more mysterious, a new study suggests.

Miniature or primordial black holes (PBHs) are black holes thought to have formed in the first fractions of a second after the Big Bang. According to leading theories, these dime-sized singularities emerged from rapidly collapsing regions of thick, hot gas.

Infinitely dense pockets of spacetime are how many physicists explain the universe's dark matter, a mysterious entity that, despite being completely invisible, makes the universe much heavier than matter. that we see can explain.

But while this hypothesis is popular, it presents a big problem: We haven't yet directly observed primordial black holes. Now, a new study offers a possible explanation as to why they didn't form, throwing cosmology's dark matter problem open to wider speculation.

According to research, the modern universe could have taken shape with far fewer primordial black holes than previous models had estimated. The researchers published their results on May 29 in the journal Physical Examination Letters.

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“Many researchers believe that they [primordial black holes] are good candidates for dark matter, but there would have to be a lot of them to satisfy this theory,” said the lead author. Jason Kristianograduate student in theoretical physics at the University of Tokyo, said in a statement. “They are also interesting for other reasons, because since the recent innovation of gravitational wave astronomy, binary black hole mergers have been discovered, which can be explained if PBHs exist in large numbers. But Despite these strong reasons for their expected abundance, we have not seen any directly, and we now have a model that should explain why this is the case.”

A hole in the image

The universe began 13.8 billion years ago with big Bangcausing the young cosmos to explode outwards due to an invisible force known as dark energy.

As the universe grew, ordinary matter, which interacts with light, congealed around clusters of invisible particles. black matter to create the first galaxies, linked together by a vast cosmic web. Today, cosmologists believe that ordinary matter, dark matter, and dark energy make up about 5%, 25%, and 70%, respectively, of the composition of the universe.

Initially, the universe was opaque, a broth of plasma that no light could pass through without being trapped by the electromagnetic fields produced by moving charges. Yet after 380,000 years of cooling and expansion, the plasma finally recombined into neutral matter, emitting static microwaves that became the first light in the universe, the cosmic microwave background (CMB).

The cosmic microwave background: the “baby photo” of the universe taken by the European Space Agency’s Planck satellite (Image credit: European Space Agency)

Cosmologists searched for these first black holes by studying this first baby image of the universe. Yet, so far, none have been found.

Some physicists think it's possible that they haven't discovered the large number of primordial black holes needed to explain dark matter simply because they haven't yet learned how to detect them.

But by applying a model built on an advanced form of quantum mechanics called quantum field theory to the problem, the researchers behind the new study came to a different conclusion: We can't find any primordial black holes because most of them simply aren't. there.

Primordial black holes are believed to have appeared as a result of the collapse of short but powerful gravitational waves propagating through the universe. By applying their model to these waves, the researchers discovered that it would take far fewer of these waves to combine than other theories estimate in order to shape larger structures across the universe. And the fewer waves needed to recreate the image, the fewer primordial black holes there are.

“It is widely believed that the collapse of short but strong wavelengths in the early universe caused the creation of primordial black holes,” Kristiano said. “Our study suggests that there should be far fewer PBHs than would be necessary if they are indeed good candidates for dark matter or gravitational wave events.”

To confirm their theory, researchers will turn to future hypersensitive gravitational wave detectors like the Laser Interferometer Space Antenna (LISA) Projectwhich should be sent into space aboard an Ariane 3 rocket in 2035.