More than a quarter of a century ago, astrophysicists witnessed an unexpected discovery while observing a distant supernova – the expansion speed of the universe appeared to be increasing. A recent study conducted by scientists from the University of Geneva (Unige) and Toulouse III – Paul Sabatier University has brought into question the ability of renowned physics laws to explain this phenomenon.
Based on the findings from the Dark Energy Survey, the research team identified discrepancies between the predictions made by famous physicists and the current understanding of the history of space. The article published in the journal Nature Communications suggests that the general theory of relativity, a long-standing cornerstone in the realm of physical theories about the Universe, may not be able to account for all the phenomena observed by astrophysicists on a larger scale.
According to Einstein’s theory, the presence of massive objects warps space and time, creating gravitational wells that result in the phenomenon of gravitational lenses. This effect, first confirmed in 1919 during a solar eclipse, has since become a crucial tool for astronomers in their exploration of the Universe.
The research team from Unige and Toulouse III utilized data from the Dark Energy Survey and detailed mapping of hundreds of millions of galaxies to gather unprecedented information about the accelerating expansion of the Universe. Their focus was on examining the distortion of time and space to test the validity of Einstein’s theories.
Camilla Bonvin, Associate Professor in the theoretical physics department at Unige, highlighted that for the first time, Dark Energy Survey data was utilized to directly measure the distortion of time and space, allowing for a comparison with Einstein’s predictions.
By analyzing over 100 million galaxies, the scientists tracked the evolution of gravitational wells at four distinct time intervals – around 3.5 billion, 5 billion, 6 billion, and 7 billion years ago. The results indicated that the depth of gravitational wells aligned with Einstein’s predictions for the earlier periods (6 and 7 billion years ago), but were smaller than expected in the later stages.
Isaac Tutusaus, a young astronomer from the Institute for Research in Astrophysics and Planetology (Irap/OMP) at the University of Toulouse III – Paul Sabatier University and the lead author of the study, pointed out an intriguing observation: the reduced depth of the wells coincided with the timeframe when the universe’s acceleration presumably commenced. The team speculates that both the accelerated expansion and the sluggish growth of gravitational wells may share a common explanation – suggesting that gravity behaves differently on a large scale than what the established theory had predicted.