Star follows the Mayall telescope in Arizona, which houses the Spectroscopic Instrument of Black Energy
Luke Tyas / Berkeley Lab
Dark Energy is one of the most mysterious characteristics of our universe – we do not know what it is, but it controls the way the universe is developing, as well as its ultimate fate. Now, a study of millions of celestial objects has revealed that we may have thought of all this bad, with potentially dramatic consequences for the cosmos.
“This is the biggest index that we have on the nature of the dark energy in the approximately 25 years since we discovered it,” explains Adam Riess At Johns Hopkins University in Maryland.
The result comes from three years of data collected by the black energy spectroscopic instrument (DESI) in Arizona. By combining this data with other measures, such as cards of the Cosmic microwave background radiation And supernovae, the Desi team concluded that dark energy can have changed over time – directly contradicting the standard cosmology model, called Lambda -CDM.
“This is the point of human knowledge,” explains the member of the Desi team Will Percival At the University of Waterloo in Canada. “We see something incredible with the whole universe.”
Desi is mounted on a telescope and works by measuring the “red change“Light emitted by distant galaxies, or how the wavelengths of this light are stretched as it evolves in the universe. From this, researchers can determine how the universe has widened during the light trip and calculate how this expansion changes.
For decades, physicists have agreed that the universe develops at a fixed acceleration rate, a cosmological constant known as the lambda which was interpreted as the push of dark energy. But in April 2024, Desi's measures showed the first clues that the universe can actually accelerate less quickly over time – Make the cosmological constant not so constant.
Riess, who is not part of the Desi team, said that at the time, he was not sure whether the observation would persist with more data. In fact, it only became stronger. “It is very exciting for me that it seems to me that (the team) found no problem in the analysis after another year, and after adding more data. If something, the result is more important, ”he says.
That said, the observation still does not respond to the statistical level “5 sigma” that physicists use conventionally to mark a discovery as authentic, rather than a statistical dynamism. The current analysis reaches at most 4.2 Sigma, but member of the team Mustapha Isaac-Boushaki At the University of Texas in Dallas, the team believes that, while Desi continues to take data, the result should reach 5 Sigma within two years. “This result on dark energy is something that we did not expect to happen in our lives,” he said.
A reassurance, says Ishak-Boushaki, is that the observation was not based solely on Desi's data, but also on several other surveys in the universe. Riess compares the situation to a stool on several legs, where the rupture of a leg – or the deletion of a set of data – is not part of the conclusion.
Assuming that the legs hold, the universe could be very different from our current image. If dark energy continues to weaken, the universe can reach a state where it develops at a constant pace instead more quickly and faster, explains Ishak-Boushaki. Some dramatic scenarios also become more plausible, such as the “Big Crunch”, where the cosmos begins to contract instead of developing and finally collapsehe said.
The exact future of the universe remains an open question, and Desi is not the only tool that researchers use to answer them. Riess underlines several other surveys on the universe, such as NASA Nancy Grace Roman Space Telescope and the Vera Rubin Observatory In Chile, which are designed to shed light on the true nature of dark energy.
While mathematical models For a universe with a dark energy that still changes to make up for these observations, Percival says that he expects that future theoretical work will help to conceive even more experiences that will directly test our hypotheses on this mysterious force.
“Regarding the theoretical models, the Pandora box has just opened. We were stuck with a cosmological constant, ”explains Ishak-Boushaki. “We are no longer stuck.”
Spend a weekend with some of the most brilliant spirits in science, while you explore the mysteries of the universe in an exciting program that includes an excursion to see the emblematic Lovell telescope.
Mysteries of the universe: Cheshire, England
