According to new research, supermassive black holes may carry the engines driving the universe’s expansion or mysterious dark energy. The existence of dark energy has been proven based on the observation of stars and galaxies, but so far no one has been able to find out its nature and source.

The familiar matter around us makes up only 5% of everything in the universe. The remaining 27% of the universe is made up of dark matter, which does not absorb or emit any light. On the other hand, a large part of the universe, or nearly 68% of it consists of dark energy.

According to new evidence, black holes may be the source of dark energy that is accelerating the expansion of the universe. This research is the result of the work of 17 astronomers in nine countries, which was conducted under the supervision of the University of Hawaii. British researchers from Raleigh Space, England’s Open University, and King’s College London collaborated in this research.

By comparing supermassive black holes spanning 9 billion years of the universe’s history, researchers have found a clue that the greedy giant objects at the heart of most galaxies could be the source of dark energy. The articles of this research were published in The Astrophysical Journal and The Astrophysical Journal Letters on February 2 and 15. Chris Pearson, one of the authors of the study and an astrophysicist at the Appleton Rutherford Laboratory (RAL) in the UK says:

If the theory of this research is correct, it could revolutionize the whole of cosmology, because at least we have found a solution to the origin of dark energy, which has puzzled cosmologists and theoretical physicists for more than twenty years.

The theory that black holes can carry something called vacuum energy (an embodiment of dark energy) is not new, and the discussion of its theory actually goes back to the 1960s; But the new research assumes that dark energy (and therefore the mass of black holes) increases over time as the universe expands. Researchers have shown how much of the universe’s dark energy can be attributed to this process. According to the findings, black holes could hold the answer to the total amount of dark energy in the current universe. The result of this puzzle can solve one of the most fundamental problems of modern cosmology.

Our universe began with the Big Bang about 13.7 billion years ago. The energy from this explosion of space once caused the universe to expand so rapidly that all the galaxies were moving away from each other at breakneck speed. However, astronomers expected the rate of this expansion to slow down due to the gravitational influence of all the matter in the universe. This attitude toward the world prevailed until the 1990s; That is when the Hubble Space Telescope made a strange discovery. Observations of distant exploding stars have shown that in the past the universe was expanding at a slower rate than it is now.

Therefore, contrary to the previous idea, not only the expansion of the universe has not slowed down due to gravity, but it is increasing and speeding up. This result was very unexpected and astronomers sought to justify it. Thus, it was assumed that “dark energy” pushes objects away from each other with great power. The concept of dark energy was very similar to a cosmic constant proposed by Albert Einstein that opposes gravity and prevents the universe from collapsing but was later rejected.

But what exactly is dark energy? The answer to this question seems to lie in another cosmic mystery: black holes. Black holes are usually born when massive stars explode and die. The gravity and pressure in these intense explosions compress a large amount of material into a small space. For example, a star roughly the same mass as the Sun can be compressed into a space of only a few tens of kilometers.

The gravitational pull of a black hole is so strong that even light cannot escape it and everything is attracted to it. At the center of the black hole is a space called singularity, where matter reaches the point of infinite density. The point is that singularities should not exist in nature.

Black holes at the center of galaxies are much more massive than black holes from the death of stars. The mass of galactic “massive” black holes can reach millions to billions of times the mass of the Sun. All black holes increase in size by accreting matter and swallowing nearby stars or merging with other black holes; Therefore, we expect these objects to become larger as they age. In the latest paper, researchers investigated the supermassive black holes at the centers of galaxies and found that the mass of these objects has increased over billions of years.

The researchers compared the past and present observations of elliptical galaxies that lack the star formation process. These dead galaxies have used up all their fuel, and as a result, their increase in the number of black holes over time cannot be attributed to normal processes that involve the growth of black holes by accreting matter.

Instead, the researchers suggested that these black holes actually carry vacuum energy, which has a direct relationship with the expansion of the universe, so as the universe expands, their mass also increases.

Two groups of researchers compared the mass of black holes at the center of two sets of galaxies. They were a young, distant cluster of galaxies with lights originating nine billion years ago, while the closer, older group was only a few million light-years away. Astronomers found that supermassive black holes have grown between seven and twenty times larger than before so this growth cannot be explained simply by swallowing stars or colliding and merging with other black holes.

As a result, it was hypothesized that black holes are probably growing along with the universe, and with a type of hypothetical energy known as dark energy or vacuum that leads to their expansion, they overcome the forces of light absorption and destruction of the stars in their center.

If dark energy is expanding inside the core of black holes, it can solve two long-standing puzzles of Einstein’s general relativity; A theory that shows how gravity affects the universe on massive scales. The new finding firstly proves how the universe does not fall apart due to the overwhelming force of gravity, and secondly, it eliminates the need for singularities (points of infinity where the laws of physics are violated) to describe the workings of the dark heart of black holes.

To confirm their findings, astronomers need more observations of the mass of black holes over time, and at the same time, they need to examine the increase in mass as the universe expands.

Dark energy has been postulated as a stable force in the universe, both in the current era and throughout the history of the universe; But new data suggests that dark energy may be more variable, getting stronger or weaker over time, reversing or even disappearing.

Adam Reiss, an astronomer at Johns Hopkins University and the Space Telescope Science Institute in Baltimore, who was not involved in the new study, was quoted by the New York Times as saying, “The new finding may be the first real clue we’ve had in 25 years about the nature of dark energy.” In 2011, Reiss won the Nobel Prize in Physics along with two other astronomers for the discovery of dark energy.

The recent conclusion, if confirmed, could save astronomers and other scientists from predicting the ultimate fate of the universe. If the dark energy has a constant effect over time, it will eventually push all the stars and galaxies away from each other so much that even the atoms may disintegrate and the universe and all life in it, light, and energy will be destroyed forever. Instead, it appears that dark energy can change course and steer the universe toward a more fruitful future.

The recent discovery is considered an initial report and has been published as a series of articles by the group responsible for an international project called “Dark Energy Spectroscopy Instrument” or DESI for short. The group has just begun a five-year effort to create a three-dimensional map of the positions and velocities of 40 million galaxies over the 11 billion-year history of the universe. The researchers made their initial map based on the first year of observations of just six million galaxies. The results were presented April 4 at the American Physical Society meeting in Sacramento, California, and at a conference in Italy.

“So far we’re seeing initial consistency with our best model of the universe,” DESI director Michael Levy said in a statement released by Lawrence Berkeley National Laboratory, the center overseeing the project. “But we also see some potentially interesting differences that may indicate the evolution of dark energy over time.”

“The DESI team didn’t expect to find the treasure so soon,” Natalie Palanque-Delaberville, an astrophysicist at Lawrence Berkeley Lab and project spokeswoman, said in an interview. The first year’s results were designed solely to confirm what we already knew. “We thought we would basically approve the standard model.” But the unknowns appeared before the eyes of the researchers.

University of Chicago astrophysicist Wendy Friedman, who led the scientific effort to measure the expansion of the universe, described the team’s results as “tremendous findings that have the potential to open a new window into understanding dark energy.” As the dominant force in the universe, dark energy remains the greatest mystery in cosmology.

The idea of ​​dark energy was proposed in 1998; When two competing groups of astronomers, including Dr. Rees, discovered that the rate of expansion of the universe was increasing rather than decreasing, contrary to what most scientists expected. Early observations seemed to show that dark energy behaved just like the famous ” fudge factor ” denoted by the Greek letter lambda. Albert Einstein included lambda in his equations to explain why the universe does not collapse due to its own gravity; But later he called this action his biggest mistake.

However, Einstein probably judged too soon. Lambda, as formulated by Einstein, was a property of space itself: as the universe expands, the more space there is, the more dark energy there is, which pushes ever harder, eventually leading to an unbridled, lightless future.

Dark energy was placed in the standard model called LCDM, consisting of 70% dark energy (lambda), 25% cold dark matter (a collection of low-speed alien particles), and 5% atomic matter. Although this model has now been discredited by the James Webb Space Telescope , it still holds its validity. However, what if dark energy is not as stable as the cosmological model assumes?

The problem is related to a parameter called w, a special measure for measuring the density or intensity of dark energy. In Einstein’s version of dark energy, the value of this parameter remains constant negative one throughout the life of the universe. Cosmologists have used this value in their models for the past 25 years.

The Desi project, 14 years in the making, is designed to test the stability of this energy by measuring the expansion rate of the universe at different times in the past. In order to do this, scientists equipped one of the telescopes of the Keith Peak National Observatory in Arizona, USA, with five thousand optical fiber detectors that can perform spectroscopy on a large number of galaxies at the same time to find out how fast they are moving away from Earth.

The researchers used fluctuations in the cosmic distribution of galaxies, known as baryonic acoustic variations , as a measure of distance. The sound waves in the hot plasma accumulated in the universe, when it was only 380,000 years old, carved the oscillations on the universe. At that time, the oscillations were half a million light years across. 13.5 billion years later, the universe has expanded a thousandfold, and the oscillations, now 500 million light-years across, serve as convenient rulers for cosmic measurements.

Desi scientists divided the last 11 billion years of the universe into 7 time periods and measured the size of the fluctuations and the speed of the galaxies in them moving away from us and from each other. When the researchers put all the data together, they found that the assumption that dark energy is constant does not explain the expansion of the universe. Galaxies appeared closer than they should be in the last three periods; An observation that suggests dark energy may be evolving over time.

“We’re actually seeing a clue that the properties of dark energy don’t fit a simple cosmological constant, and instead may have some deviations,” says Dr. Palanque-Delaberville. However, he believes that the new finding is too weak and is not considered proof yet. Time and more data will determine the fate of dark energy and the researchers’ tested model.