Einstein’s Theory Of Relativity Proved Right By Major Gravity Experiment On A Nearby Galaxy

Albert Einstein has been proven right in another galaxy, reports Phys.org, citing the University of Portsmouth in the U.K.

In what is being hailed as “the most precise test of gravity outside our own solar system,” an international team of scientists have shown that Einstein’s theory of gravity, known as the General Theory of Relativity, is the correct theory of gravity on an astronomical scale.

Postulated in 1915, Einstein’s general relativity (GR) theory can explain why the universe is expanding so fast while also accounting for dark energy and dark matter, notes Space.com.

While this theory has been tested various times within the confines of our solar system, the team’s latest research has taken things a bit further.

To see if Einstein’s theory of relativity can be confirmed within individual galaxies, the scientists tested GR on a larger astronomical scale than ever before, by looking at the gravity of a nearby galaxy dubbed ESO325-G004 (E325, for short).

Located some 500 million light-years from Earth, this galaxy is known as a “gravitational lens” — an object that helps researchers observe gravitational lensing, an effect of gravitation associated with Einstein’s theory of relativity and which states that mass can bend light, explains CFHT LenS.

Study lead author Dr. Thomas Collett of the university’s Institute of Cosmology and Gravitation, explains the phenomenon.

“General Relativity predicts that massive objects deform space-time, this means that when light passes near another galaxy the light’s path is deflected. If two galaxies are aligned along our line of sight this can give rise to a phenomenon called strong gravitational lensing, where we see multiple images of the background galaxy.”

In the video interview below, published by the European Southern Observatory (ESO), Collett shows that, when the foreground galaxy is big enough to cause a large warp in space-time, the images of the background galaxy are “warped into what we call an ‘Einstein ring,’ and the radius of that ring tells you how much warping of space-time in going on.”

As Collett points out, if the mass of the foreground galaxy is known, the separation observed between these multiple images of the background galaxy indicates whether Einstein’s proposed theory of gravity really works in these galaxies’ particular case.

While astronomers know of a few hundred strong gravitational lenses, E325 is among the closest of them and provides a great opportunity to verify whether GR is valid in another galaxy.

Galaxy E325 in the Abell S0740 galaxy cluster.
Galaxy E325 in the Abell S0740 galaxy cluster.Featured image credit: NASA, ESA, Hubble Heritage Team

In the image above, E325 is the giant elliptical galaxy in the center of the galaxy cluster, known as Abell S0740. According to NASA, this galaxy is 100 billion times more massive than our sun.

To test Einstein’s theory of gravity, Collette’s team essentially used E325 as a laboratory and scoped out the galaxy with two telescopes, NASA’s Hubble Space Telescope and ESO’s Very Large Telescope (VLT) in Chile.

While Hubble took an image of the gravitational lensing observed in E325 to measure the radius of the “Einstein ring” (how big it is), the VLT measured how fast the stars in the lensing galaxy are moving, to find out E325’s mass, Collette revealed in the university news release.

“The result was just what GR predicts with nine percent precision. This is the most precise extrasolar test of GR to date, from just one galaxy.”

The new research, published today in the journal Science, proves that Einstein’s theory of relativity is valid on individual galactic scales, as seen in this distant galaxy.

“It is so satisfying to use the best telescopes in the world to challenge Einstein, only to find out how right he was,” said study co-author Prof. Bob Nichol, who runs the university’s institute.