The rapid expansion of the universe has been the most perplexing enigma in physics.
To unravel this cosmic puzzle, scientists turn to the fundamental laws of physics, including Albert Einstein’s theory of general relativity.
A team of scientists compared Einstein’s theory of general relativity with data from the Dark Energy Survey. They found a “slight discrepancy” in the behavior of gravity at different cosmic times.
This means that this theory might not hold true for all parts of the universe.
The study says that the gravitational distortions observed in distant galaxies exhibit subtle discrepancies with the predictions of Einstein’s theory.
Distortion of spacetime
Einstein’s theory of general relativity fundamentally changed our understanding of gravity.
He proposed that massive objects distort the fabric of spacetime, much like a heavy ball bending a rubber sheet.
These depressions in spacetime, caused by the gravitational pull of massive celestial bodies, are known as gravitational wells.
When massive objects, like galaxies or black holes, warp the fabric of spacetime gravitational lensing occurs. This warping bends the path of light passing nearby, similar to how a glass lens bends light.
This phenomenon allows scientists to study distant objects and gain insights into the universe’s structure and expansion.
The 1919 solar eclipse observation confirmed Einstein’s theory of general relativity. It showed that light bends twice as much as predicted by Newton’s theory due to the combined effects of warped space and time.
Analysis of distant galaxies
The Dark Energy Survey seeks to probe the underlying causes of the universe’s accelerating expansion. This astronomical survey has mapped hundreds of millions of galaxies, which helped the team in this new study.
‘‘In our study, we used this data to directly measure the distortion of time and space, enabling us to compare our findings with Einstein’s predictions,’’ said Camille Bonvin, associate professor from the University of Geneva.
The team analyzed 100 million galaxies at various points in the universe’s history — particularly 3.5, 5, 6, and 7 billion years ago. This analysis allowed them to study the evolution of gravitational wells over time.
‘‘We discovered that in the distant past — 6 and 7 billion years ago — the depth of the wells aligns well with Einstein’s predictions. However, closer to today, 3.5 and 5 billion years ago, they are slightly shallower than predicted by Einstein,’’ explained Isaac Tutusaus, an assistant astronomer from the Paul Sabatier University.
This suggests that gravity could behave differently at large cosmic scales than predicted by Einstein’s theory.
‘‘Our results show that Einstein’s predictions have an incompatibility of 3 sigma with measurements. In the language of physics, such an incompatibility threshold arouses our interest and calls for further investigations. But this incompatibility is not large enough, at this stage, to invalidate Einstein’s theory, said Nastassia Grimm, a postdoctoral researcher at UNIGE, in the press release.
Researchers are now working to examine data from the Euclid space telescope.
Euclid’s precise measurements of gravitational lensing and its observation of 1.5 billion galaxies will allow for a more accurate understanding of spacetime distortions. It will help better test Einstein’s theory of general relativity at a universal scale.
The findings were published in the journal Nature Communications.
