While observing huge cosmic distances, scientists have conducted one of the most accurate tests of Albert Einstein’s theory of general relativity yet, and just like all the other tests, the theory has passed this one with flying colors. At the level of precision, we now possess, our current understanding of gravity appears to be accurate. The test has significant ramifications for the nature of dark energy, a central cosmic puzzle.
Astronomers first identified the universe’s accelerating expansion more than 20 years ago. The prevailing theory for this acceleration’s cause is dark energy, a sphere of energy spanning space and time that acts as an attractive force akin to antigravity. Alternative theories contend that our understanding of gravity may be imperfect and that gravity may differ slightly at greater scales despite the lack of strong evidence for what dark energy accomplishes.
In research on galaxies studied at distances up to 5 billion light-years, the worldwide Dark Energy Survey identified the modest warping of space-time caused by gravity. The team was able to ascertain the strength of gravity in the distant past thanks to an effect known as weak gravitational lensing. They do not discover any proof of physics outside of our existing understanding of the universe, as far as they can discern.
Although this test is significant, it is not the last word on the subject. If it were, it wouldn’t be science. In 2023, the European Space Agency will launch the six-year Euclid observatory into orbit. This analysis will be pushed by Euclid up to an 8 billion light-year distance. The Nancy Grace Roman Space Telescope, which is to be launched by NASA in 2027, will observe weak gravitational lensing up to 11 billion light-years away.
As measurements become more accurate, there is still room to question Einstein’s theory of gravity, according to co-author Agnès Ferté, a postdoctoral researcher at JPL who carried out the study.
But before we’re prepared for Euclid and Roman, there is still so much to do. Therefore, it’s crucial that we work together on this issue with scientists from all across the world, just as we did with the Dark Energy Survey. About the nature of dark energy and the similarly enigmatic dark matter, there are many unknowns. However, they remain the dominant theory for the time being.