An international team of researchers has achieved the most precise measurements of gravity at cosmological scales to date. They performed one of the most stringent tests to date to verify Albert Einstein’s general relativity theory, that too, at cosmological scales. The test results have confirmed that gravity behaves just as predicted across billions of light years.
Among the researchers was an Indian team led by Shadab Alam from the Tata Institute of Fundamental Research (TIFR), Mumbai. The research output is primarily based on a year-long data collection from the Dark Energy Spectroscopic Instrument (DESI). This unique piece of equipment, once mounted over a telescope, can simultaneously capture light from 5,000 galaxies.
The earlier gravity tests on similar cosmological scales required inputs lasting decade-long data campaigns, but with DESI’s data gathered over just one year, making this is a remarkable achievement.
“We have been able to calculate the most precise velocities of the galaxies at cosmological scales to date. This helped us understand how the galaxies populated the universe across different epochs during its evolution. DESI has precisely measured the cosmic structure, telling us the role that gravity could have played in shaping our universe,” said Alam.
To put things in a better perspective, gravity was previously measured over an area as small as a water droplet (solar system), whereas in the latest attempt, the international team tested it over a vast ocean (cosmos).
The TIFR team’s contribution was seminal in this work as they developed highly sophisticated galaxy models and made extensive use of the cosmological catalogue to validate and test the theories.
“Measuring gravity’s influence across vast distances (100s of million Parsecs) required both precise modelling and analysis techniques. DESI’s one-year data has confirmed that gravity behaves the same way across billions of light-years as it does in our neighbourhood cosmic backgrounds,” added Alam.
DESI is led by the US Department of Energy and is located at Kitt Peak National Observatory, Arizona in the US. Earlier this year, DESI had facilitated the most-detailed 3D mapping of the universe. It will continue to gather data from a large array of galaxies till the end of its stipulated five-year period.
The collective data generated by DESI is expected to help scientists better understand dark matter and energy and generate newer information on the universe’s fundamental laws. Understanding the nature of dark energy has been of great interest as it holds the potential to delve into the universe’s origins and evolution over the past 13 billion years.
