Scientists who analysed the largest sample of James Webb Space Telescope (JWST) data collected over its first two years in space have concluded that a new feature and not a flaw in telescope measurements could be the reason why the universe is expanding faster today than it did in its infancy billions of years ago. The decades-long mystery has kept scientists across the world confused and while some believe that dark energy might be driving the change in acceleration, others state that since we have no clear idea what constitutes dark energy, a conclusive theory is still required.
The conundrum, referred to as the Hubble tension, can change the field of physics altogether. In 2019, the measurements by the Hubble Space Telescope confirmed the problem was real. Fast forward to 2024, and JWT’s new data, published in The Astrophysical Journal, offers a crucial cross-check to address the mismatch in measurements of the universe’s mysterious expansion.
“The discrepancy between the observed expansion rate of the universe and the predictions of the standard model suggests that our understanding of the universe may be incomplete,” said Nobel laureate and lead author Adam Riess.
“With two NASA flagship telescopes now confirming each other’s findings, we must take this [Hubble tension] problem very seriously-it’s a challenge but also an incredible opportunity to learn more about our universe.”
Mr Riess’ team used three different methods to verify the Hubble telescope’s measure of the expansion rate of the universe. While observations from both telescopes aligned closely, they still produce higher values compared to projections made using the “standard model of cosmology”, which calculates the expansion rate using data from cosmic microwave background — the faint radiation left after the Big Bang.
The standard model yields a Hubble constant of about 67-68 kilometres per second per megaparsec while the data from two telescopes yield a value of 70 to 76, with a mean of 73 km/s/Mpc. Such mismatch in numbers which is too large to be bridged by approximation, has left the scientists perplexed.
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Black holes driving the universe’s expansion?
While Mr Reiss and his colleagues search for answers, a study published last month claimed that black holes were driving the expansion of the universe instead of dark energy.
For a long time, scientists have believed in the inflationary universe theory which states that almost 14 billion years ago, at the start of the Big Bang, a mysterious energy, believed to be dark energy, accelerated the expansion of the infant universe.
However, the radical new study challenges this notion. After analysing data from the Dark Energy Spectroscopic Instrument (DESI), scientists claimed that the density of dark matter increased over time which agrees with how the amount and mass of black holes increased as the universe aged.
Researchers say the findings of the study could lead to a renewed understanding of the universe and the true composition of black holes.
