Albert Einstein's theory of general relativity has been proven correct on the largest scale ever. Analysis of millions of galaxies showed that the way they evolved and clustered over billions of years was consistent with his predictions.

Ever since Einstein proposed his theory of gravity more than a century ago, researchers have been trying to find scenarios in which the theory of gravity doesn't hold true. However, no such test had ever been performed at the level of the longest distances in the universe. Mustafa Ishak-Bushaki At the University of Texas at Dallas. He and his colleagues conducted the experiment using data from the Dark Energy Spectroscopy Instrument (DESI) in Arizona.

The details of the structure of the universe and how it has changed over time provide a powerful test of how well we understand gravity. Because it was this force that shaped galaxies as they evolved from small fluctuations in the distribution of matter in the early universe.

DESI has so far collected data on how nearly 6 million galaxies have come together over the past 11 billion years. Ishak-Boushaki and his colleagues combined this with the results of several other large-scale surveys, including the cosmic microwave background radiation and supernova mapping. They then compared this to the predictions of a theory of gravity that encompasses both Einstein's ideas and more modern modified theories of gravity. They did not discover any deviations from Einstein's gravity. Ishak-Boushaki says that while there is some uncertainty in the measurements, there is still no strong evidence that theories that deviate from Einstein's can more accurately capture the state of the universe. .

Itamar Allari Professors at Brown University in Rhode Island say that although general relativity has been shown to hold up in very precise tests performed in the laboratory, it is important that it can be tested at all scales, including the entire universe. states. This eliminates the possibility that Einstein correctly predicted objects of one size but not others, he says.

The new analysis also provides hints about how dark energy, the mysterious force thought to be responsible for the accelerating expansion of the universe, fits into theories of gravity. Nathalie Palanque-Dravuille At Lawrence Berkeley National Laboratory, California. Einstein's early formulations of general relativity included a cosmological constant (a type of antigravity that plays the same role as dark energy), but earlier DESI results showed that dark energy is not constant. It suggested that. That may have changed as the universe aged, Palanque-Delabouille said.

“The fact that we see that we agree; [general relativity] And any deviation from this cosmological constant opens up a Pandora's box of what the data can actually tell us,” says Ishak Boushaki.

DESI will continue to collect data for several more years, eventually recording the locations and properties of 40 million galaxies, which the three scientists agree will support the theory of general relativity and dark energy. He said it would be clear how to combine them correctly. This new analysis used only one year of data from DESI, but in March 2025 the team plans to share findings from the instrument's first three years of observations.

Allari said these results could help pinpoint changes in the Hubble constant, a measure of the rate of expansion of the universe, narrow down the mass of elusive particles called neutrinos, and even search for new particles. He said he expects it to be significant in this important respect. Cosmic components such as “dark radiation”.

“This analysis will have implications not just for gravity, but for cosmology as a whole,” he says.