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The study suggests these primordial black holes could have absorbed free quarks and gluons, making them different from typical black holes formed by collapsing stars. They would be incredibly small, yet could account for much of the universe’s dark matter.

For decades, scientists have struggled to explain the lack of visible matter in the universe.

Domain walls, long a divisive topic in physics, may be ideal explanations for some bizarre cosmic quirks.

By Anil Ananthaswamy

“As long as they live for long enough, they will always become large cosmological beasts,” says Ricardo Ferreira, a cosmologist at the University of Coimbra in Portugal. He’s not talking about actual beasts but rather about hypothetical humongous sheets of spacetime that could divide one region of the universe from another. Such so-called domain walls are the natural outcome of theories that try to solve some of the deepest mysteries in physics, such as the origins of gravity. As Ferreira says, however, had they formed after the big bang, by today they’d be the dominant source of energy in our universe, and there’s no evidence that’s the case. So any theory invoking their existence has been considered suspect—until now, perhaps.

The standard theory of cosmology—which says 95% of the universe is made up of unknown stuff we can’t see—has passed its strictest test yet. The first results released from an instrument designed to study the cosmic effects of mysterious dark energy confirm that, to the nearest 1%, the universe has evolved over the past 11 billion years just as theorists have predicted.

The findings, presented today in a series of talks at the American Physical Society meeting in Sacramento, California, and the Moriond meeting in Italy, as well as in a set of preprints posted to arXiv, come from the Dark Energy Spectroscopic Instrument (DESI), which has logged more than 6 million galaxies in deep space to construct the largest 3D map of the universe yet compiled.

“It’s a tremendous instrument and a major result,” says Eric Gawiser, a cosmologist at Rutgers University who was not involved with the work. “The universe DESI is finding is very sensible, with tantalizing hints of a more interesting one.”

The Multiverse fuels some of the 21st century’s best fiction stories. But its supporting pillars are on extremely stable scientific footing.

After its “birth” in the Big Bang, the universe consisted mainly of hydrogen and a few helium atoms. These are the lightest elements in the periodic table. More-or-less all elements heavier than helium were produced in the 13.8 billion years between the Big Bang and the present day.

Stars have produced many of these heavier elements through the process of nuclear fusion. However, this only makes elements as heavy as iron. The creation of any heavier elements would consume energy instead of releasing it.

In order to explain the presence of these heavier elements today, it’s necessary to find phenomena that can produce them. One type of event that fits the bill is a gamma-ray burst (GRB)—the most powerful class of explosion in the universe. These can erupt with a quintillion (10 followed by 18 zeros) times the luminosity of our sun, and are thought to be caused by several types of event.

A JWST/MIRI spectrum of an early quasar in the mid-infrared indicates that J1120+0641 had a mature feeding structure 760 Myr after the Big Bang. This finding suggests that supermassive black holes and their torii build up surprisingly quickly.

A new theory of quantum gravity, which attempts to unite quantum physics with Einstein’s relativity, could help solve the puzzle of the universe’s expansion, a theoretical paper suggests.

Leonardo DiCaprio’s dream.

Stars at the Milky Way’s center stay young forever, scientists claim, by feeding off dark matter particles that are abundant there.

The detailed calculations demonstrate that black holes of 10 solar masses may comprise at most 1.2% of dark matter, 100 solar mass black holes—3.0% of dark matter, and 1,000 solar mass black holes—11% of dark matter.

“Our observations indicate that primordial black holes cannot comprise a significant fraction of the dark matter, and simultaneously, explain the observed black hole merger rates measured by LIGO and Virgo,” says Prof. Udalski.

Therefore, other explanations are needed for massive black holes detected by LIGO and Virgo. According to one hypothesis, they formed as a product of the evolution of massive, low-metallicity stars. Another possibility involves mergers of less massive objects in dense stellar environments, such as globular clusters.