New 'mind-blowing' gravity discovery proves Einstein right again

From the tiniest fluctuations after the Big Bang, gravity has orchestrated the formation of galaxies, stars, and planets, creating the vast cosmic web we see today.

Gravity isn’t just what keeps us grounded — it’s been shaping the universe since its earliest days. Recent studies have provided the most precise tests of gravity on the grandest scales imaginable.

By examining how cosmic structures have grown over the past 11 billion years, scientists have confirmed that gravity behaves just as Einstein’s theory of general relativity predicts, even across billions of light-years.

DESI tracks gravity over 11 billion years

Pauline Zarrouk, a cosmologist at the French National Center for Scientific Research (CNRS) working at the Laboratory of Nuclear and High-Energy Physics (LPNHE), has been exploring this cosmic evolution.

In collaboration with the international team behind the Dark Energy Spectroscopic Instrument (DESI), Zarrouk and her colleagues have traced how cosmic structures grew over the past 11 billion years.

Using data from DESI, the researchers provided the most precise test to date of gravity on the largest scales.

“General relativity has been very well tested at the scale of solar systems, but we also needed to test that our assumption works at much larger scales,” Zarrouk explained.

“Studying the rate at which galaxies formed lets us directly test our theories and, so far, we’re lining up with what general relativity predicts at cosmological scales.”

Einstein is smiling from the grave

Their findings confirm that gravity behaves as Einstein’s theory of general relativity predicts, even across the immense distances of the universe.

This validation supports our leading model of the cosmos and narrows down alternative theories of gravity that have been proposed to explain puzzling observations, like the accelerating expansion of the universe often attributed to dark energy.

The study also sheds light on neutrinos — the elusive particles that zip through space almost undetected.

Previous experiments determined that the combined mass of the three types of neutrinos should be at least 0.059 electron volts (eV/c²). For perspective, an electron has a mass of about 511,000 eV/c².

DESI’s results suggest that the total mass of neutrinos should be less than 0.071 eV/c², tightening the constraints on these mysterious particles.

DESI, gravity, and cosmic structure

“Both our BAO results and the full-shape analysis are spectacular,” said Dragan Huterer, a professor at the University of Michigan and co-lead of DESI’s group interpreting the cosmological data.

“This is the first time that DESI has looked at the growth of cosmic structure. We’re showing a tremendous new ability to probe modified gravity and improve constraints on models of dark energy. And it’s only the tip of the iceberg.”

DESI is no ordinary telescope. Mounted on the Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory, it’s capable of capturing light from 5,000 galaxies at once.

Funded by the DOE Office of Science, the project is now in its fourth year of surveying the sky and aims to collect data from roughly 40 million galaxies and quasars by the time it’s done.

Testing gravity at cosmic scales is crucial. While Einstein’s theory has passed every test within our solar system, there’s always the possibility that it might behave differently across the vastness of space.

By confirming that gravity acts as expected over billions of light-years, scientists can be more confident in their models of how the universe has evolved.

Interpreting the DESI data

Dr. Mustapha Ishak-Boushaki, a professor of physics in the School of Natural Sciences and Mathematics at UT Dallas, co-led the DESI working group that interpreted the cosmological data.

“For this round of DESI results, I focused my efforts at UT Dallas on conducting a large part of the analysis on gravity, which puts constraints on how matter in the universe moves and how large-scale structures, such as clusters of galaxies, evolve,” explained Ishak-Boushaki.

“The results from DESI, combined with datasets from other experiments, are consistent with general relativity theory operating at cosmic scales, although they do not completely exclude other theories of modified gravity.”

The new results provide an extended analysis of DESI’s first year of data, which in April contributed to the largest 3D map of the universe to date and revealed hints that dark energy might be evolving over time.

“The latest analysis is also consistent with our previous findings that give preference to the theory that dark energy is not constant, but dynamic, which is a very important result for cosmic acceleration,” Ishak-Boushaki said.

How did this happen?

The collaboration is currently analyzing data from the first three years and expects to present updated measurements of dark energy and the universe’s expansion history by spring 2025.

The recent results align with earlier hints that dark energy might be evolving over time, adding to the excitement for what’s to come.

“Dark matter makes up about a quarter of the universe, and dark energy makes up another 70 percent, and we don’t really know what either one is,” said Mark Maus, a PhD student at Berkeley Lab and UC Berkeley who worked on theory and validation modeling pipelines for the new analysis.

“The idea that we can take pictures of the universe and tackle these big, fundamental questions is mind-blowing.”

The study utilized nearly 6 million galaxies and quasars, allowing researchers to peer up to 11 billion years into the past.

What’s next for DESI and gravity?

To sum it all up, with just one year of data, DESI has made the most precise overall measurement of the growth of cosmic structures, surpassing previous efforts that took decades.

The DESI project is remarkable not just for its technological capabilities but also for its collaborative spirit.

With over 900 researchers from more than 70 institutions worldwide, it’s a testament to what can be achieved when the global scientific community comes together.

As we await the next round of results, one can’t help but wonder: What other secrets of the universe are waiting to be uncovered?

The quest to understand gravity, dark matter, and dark energy continues, and each new discovery brings us a little closer to unraveling the mysteries of the cosmos.

The full study was published in several scientific journals.

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