Einstein’s theory of general relativity passes first extragalactic test
The much-heralded theory has been tested on a large scale for the first time
Time and time again, Albert Einstein's general theory of relativity has been shown to be correct, and now – 103 years after it was proposed – it has been validated once more, this time in a distant galaxy.
Researchers using data from the Hubble Space Telescope and the European Southern Observatory's
Very Large Telescope (VLT) found that gravity in the galaxy ESO 325-G004 behaves in the same way as it does in our Solar System. In particular, it fits in with the predictions of the German-born scientist who said that objects with considerable mass can bend the light of distant objects, thereby deforming space-time (known as gravitational lensing).
As such, the study team used the VLT to measure the speed of the stars within the galaxy to calculate its mass. They then used Hubble to observe gravitational lensing on the galaxy, which is 500 million light years from Earth, to see how strongly gravity was bending the light reaching Earth. By calculating how light (and therefore space-time) was being distorted by the mass, they worked out that the galaxy's mass was within nine per cent of what the general theory of relativity predicted.
It helps put to bed alternative models of gravity by lending extra weight to the existence of dark matter and dark energy, supporting the standard model. “The universe is an amazing place, providing such lenses which we can use as our laboratories,” says study team member Bob Nichol of the University of Portsmouth.