The largest 3D map of the universe ever created is providing hints about the evolution of the cosmos, and they suggest that we may be wrong about the behaviour of dark energy, which makes up most of the universe. It seems that this mysterious force may be weakening over time.at Johns Hopkins University in Maryland, who found the first evidence for dark energy 25 years ago.
DESI researchers examined the strength of dark energy by measuring the large-scale structure and distribution of galaxies in the cosmos, which illuminates how the universe has expanded over time. The researchers then combined this information with three sets of data on supernovae, which act as so-called “Surprisingly, each of the three samples of supernovae yielded a different answer to the change in the universe’s rate of expansion over time.
Discrepancies in models are denoted by a factor called sigma, which measures the likelihood that a similar clash could have happened by chance if the models did disagree with one another. “About 3-sigma is the level we usually sit up and pay attention and call an ‘indication’ of something,” says Riess. Anything lower than that would not generally be particularly exciting to researchers – it would be too likely to be a simple coincidence.