Recent research shows that galaxies are moving apart faster than expected, casting doubt on the Standard Model of cosmology.
Edwin Hubble discovered the expansion of the universe in 1929. Since then, researchers have measured the Hubble constant: the speed at which galaxies are moving away from each other.
However, data from nearby and distant galaxies do not match, creating a conflict called the ‘Hubble tension’.
Dan Scolnic, a physicist at Duke University, and his team recently calculated a highly accurate Hubble constant using data from the Dark Energy Spectroscopic Instrument (DESI) and light patterns from Type Ia supernovae in the Coma Cluster. Their result, 76.5 kilometers per second per megaparsec, confirms a faster local expansion than the standard model predicts.
“The tension is now turning into a crisis,” said Scolnic, who led the research team.
He describes it as building a growth chart: there’s a baby photo of the Big Bang and a current image of our galactic environment, but the curve connecting these two images doesn’t match the predictions.
“This means, in a sense, that our cosmological model may be broken,” said Scolnic.
This discrepancy suggests that our understanding of the universe may be incomplete. Scientists are now debating whether errors in measurements or flaws in current theory are to blame.
In recent work, a project called the Dark Energy Spectroscopic Instrument (DESI) has provided an extended range of galaxy distances, making the process more accurate.
“The DESI collaboration delivered the very difficult part: their ladder was missing the first rung,” Scolnic said. “I knew how to get that, and I knew that would give us one of the most accurate measurements of the Hubble constant that we could get, so when their paper came out I dropped absolutely everything and worked non-stop on this subject.”
Some believe we need new physics to explain the discrepancy, while others focus on refining the data collection.
As more powerful telescopes and advanced tools become available, researchers hope to discover the truth behind the accelerating expansion of the universe.
