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Astronomers conducting what they call the largest and most accurate survey of the history of the universe to date revealed on Thursday that there are major flaws in our understanding of dark energy, the mysterious force that is accelerating the expansion of the universe. He announced that he may have discovered something. universe.
Dark energy was thought to be a constant force present in the universe now and throughout the history of the universe. But new data suggests it may be more variable, becoming stronger or weaker, reversing, or disappearing over time.
“As Mr. Biden calls it, this is a BFD,” said Adam Reese, an astronomer at Johns Hopkins University and the Space Telescope Science Institute in Baltimore. He shared the 2011 Nobel Prize in Physics with two other astronomers for their discovery of dark energy, but was not involved in this new research. “This may be the first real clue we have about the nature of dark energy in 25 years,” he says.
If that conclusion is confirmed, it could free astronomers, and all of us, from years of grim predictions about the ultimate fate of the universe. If dark energy were to remain constant over time, it would eventually push all the stars and galaxies so far that even their atoms would be torn apart, eliminating all life, light, energy, and thought in the universe. He will be taken away and sentenced to eternal life. An incredible event in space. Rather, it appears that dark energy can change course and point the universe toward a more prosperous future.
The keywords are “might” and “possible.” The probability that this new discovery is a statistical coincidence is about 1 in 400, and the degree of uncertainty known as three sigma is lower than the gold standard for discovery, five sigma (a probability of 1 in 1.7 million). Not far behind. In the history of physics, even the Five Sigma event faded away as more data and better interpretations of data emerged.
The news was announced in the first progress report in a series of papers from a large international collaboration called the Dark Energy Spectroscopy Instrument (DESI). 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 11 billion years of cosmic time. The first map, based on the first year of observations, contains just 6 million galaxies. The results were presented today at the American Physical Society meeting in Sacramento, California, and at the Rencontre de Morion conference in Italy.
“So far we’ve seen basic agreement with the best models of the universe, but we’ve also seen some interesting differences that could indicate that dark energy is evolving over time. DESI Director Michael Levi said in the paper. A statement released by Lawrence Berkeley National Laboratory, which manages the project.
Nathalie Palanque-Delabreuil, an astrophysicist at Lawrence Berkeley Lab and a spokesperson for the project, said in an interview that the DESI team did not expect to be paid so quickly. Ta. The first year’s results were meant to simply confirm what was already known: “We thought they would basically validate the standard model,” she said.
But something unknown jumped out at them.
When the scientists combined their map with other cosmological data, they were surprised to find that it was completely inconsistent with the reliable standard model of the universe, which assumes that dark energy is constant and unchanging. Changing dark energy better fits the data points.
“It’s certainly more than just a curiosity,” Dr. Palanc-Delabouille says. “I think that’s a hint. Yes, we don’t have any proof yet, but it’s interesting.”
However, cosmologists take this hint very seriously.
Wendy Friedman, an astrophysicist at the University of Chicago who has led efforts to measure the expansion of the universe, hailed the study as “amazing data.” The results “open the possibility of a new window into understanding dark energy, the dominant constituent of the universe, which remains one of the greatest mysteries in cosmology,” she said. . It’s pretty exciting. ”
Michael Turner, a professor emeritus at the University of Chicago who coined the term “dark energy,” said in an email: This is the best news I’ve heard since the acceleration of the universe was firmly established over 20 years ago. ”
Dark energy became a hot topic in 1998, when two competing groups of astronomers, including Dr. Rees, suggested that the expansion of the universe was accelerating rather than slowing down, as most astronomers had expected. I discovered that there is. The first observation was that this dark energy acts exactly like the famous fudge element (denoted by the Greek letter lambda) that Einstein inserted into his equations to explain why the universe did not collapse under its own weight. It seemed to suggest that. He later called it the worst mistake of his life.
But perhaps he talked too much. Lambda, as formulated by Einstein, is a property of space itself. As the universe expands, the more space there is, the more dark energy exists and becomes more and more intense, ultimately leading to a runaway lightless future.
Dark energy is found in the standard model of the universe, known as the LCDM, which consists of 70 percent dark energy (lambda), 25 percent cold dark matter (a collection of slowly moving exotic particles), and 5 percent atomic matter. Replaced. So far, this model has been damaged by the new James Webb Space Telescope, but not broken. But what if dark energy is not constant, as cosmological models assume?
The problem is the parameter w., This is a measure of the density, or intensity, of dark energy. In Einstein’s version of dark energy, this number remains constant at a value of -1 throughout the life of the universe. Cosmologists have been using this value in their models for the past 25 years.
But this version of dark energy is only the simplest. “Using DESI, we achieved accuracy that exceeds that simple model,” said Dr. Palanque-Delabouille. time. “
The DESI project was developed over 14 years and aimed to test the homeostasis of dark energy by measuring how fast the universe was expanding at different times in the past. To do this, scientists equipped the Kitt Peak National Astronomical Observatory telescope with 5,000 fiber-optic detectors to simultaneously perform spectroscopic measurements of large numbers of galaxies to determine how fast they were moving away from Earth.
As a measure of distance, the researchers used irregularities in the cosmic distribution of galaxies, known as baryon acoustic oscillations. These bumps were carved into the universe by sound waves in the hot plasma that filled it when it was just 380,000 years old. At the time, this bulge was 500,000 light years across. Now, 13.5 billion years later, the universe has expanded 1,000 times, and the bump, which is 500 million light-years in diameter, serves as a useful cosmic measuring stick.
DESI scientists have divided the past 11 billion years of cosmic history into seven periods. (The universe is 13.8 billion years old.) For each, they measured the size of these bumps and the speed at which galaxies within them were moving away from us and from each other.
When the researchers put it all together, they found that the usual assumption – constant dark energy – doesn’t work to explain the expansion of the universe. Galaxies from the last three epochs appear closer than they should, suggesting that dark energy may be evolving over time.
“And while it is true that the properties of dark energy do not correspond to a simple cosmological constant,” there are hints that “there may be some deviations,” Palanc-Derabuille said. “And this is the first time something like this has happened.” But she stressed again. “It’s not proof yet. It’s too weak.”
Time and more data will reveal the fate of dark energy and the cosmological model that cosmologists have battled with.
“LCDM is being put through its paces with precision testing from all directions,” Dr. Turner said. “And it’s working. But when you put it all together, it starts to look like something is wrong, something is missing. Things just don’t quite mesh together. And DESI is the latest sign. ”
Johns Hopkins’ Dr. Reese, who was an early examiner of the DESI results, said that if the “hints” are verified, they could deduce errors from other cosmological measurements, such as the age and size of the universe. It pointed out. “This result is very interesting and should be taken seriously by us,” he wrote in an email. “Otherwise, why would we need to do an experiment like this?”
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