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Dwarf galaxy NGC 6822

Photo: M. Meixner / Webb / CSA / ESA / NASA

Physicists have mapped the past eleven billion years of the cosmos with unprecedented precision. In an initial evaluation of the so-called Desi project, they came across indications that the previous theory of the cosmos could be incorrect. One consequence: the future of the universe may turn out differently than expected.

Overall, the data was found to be in good agreement with the theoretical model of the universe, said Michael Levi, head of the Desi project and physicist at the US Lawrence Berkeley National Laboratory, in a statement. “But we also see interesting deviations.” These would possibly mean that “dark energy changes over time.” The deviations could “disappear with additional data – or not.”

"A big thing"

Astrophysicist Adam Riess from Johns Hopkins University considers the new findings to be significant. Riess received a Nobel Prize in 2011 for the discovery of dark energy and has already looked at the data that has now been published. “I take these results at face value,” he wrote to SPIEGEL in an email. If they are confirmed in further analyzes of the Desi project, that would be “a big thing.”

Dark energy is a mysterious force in the universe. It causes space to expand faster and faster and galaxies to move away from each other. Together with the so-called dark matter, which holds galaxies together through its gravitational pull, it accounts for 95 percent of the total energy in the cosmos. All visible matter such as the stars and planets together only make up five percent.

fluctuations from the early days

To this day no one knows what dark energy exactly is. Some suspect that this is due to fluctuations in the vacuum, particles and antiparticles that arise spontaneously and dissolve again into radiation. Others believe in an energy field that runs through the entire space. However, according to the generally accepted idea, the standard model of cosmology, it has the same effect at all times and is therefore constant.

The Desi scientists measured the extent of space using a telescope at the Kitt Peak National Observatory in Arizona, which they equipped with 5,000 special detectors. The data published so far is based on measurements from one year. Over the next four years, they want to expand their map of the universe from six to 40 million galaxies.

Is the universe getting kicked?

Among other things, the researchers looked at so-called baryonic acoustic oscillations, which are due to fluctuations in the mass distribution of the early universe. To put it simply, they use the strength of these waves as a kind of cosmic ruler and use it to determine the expansion of the universe at different times.

When the astronomers analyzed their data along with those of other measurements, it revealed a deviation from what would be expected if dark energy were constant according to the Standard Model of cosmology. However, it is possible that this discrepancy was caused by random fluctuations in the data. It is still statistically below the threshold that physicists usually apply to new findings.

Nobel Prize winner Riess has long been propagating that dark energy could fluctuate. He suspects that there may be a physical field that has not yet been researched in detail that can turn the mysterious force up and down again. "It's possible that such fields give the universe a kind of kick every now and then."

Big Bang backwards

Physicists also hope that a new theory of dark energy will provide an answer to the question of what the future of the universe looks like. If the force remains the same in eternity, the matter will become more and more rarefied and the universe will become darker and colder until no further life is possible anywhere.

However, if the dark energy changes, the universe may face a different fate. It could either become so strong that it tears apart galaxies, then planetary systems and finally even atoms. Or it weakens until gravity becomes the driving force. Then all matter could collapse into one point faster and faster - a kind of upside-down Big Bang.

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