An article published in “The Astrophysical Journal” reports the results of a new measurement of the universe’s expansion rate obtained using observations conducted with the James Webb Space Telescope that confirms previous results obtained with Hubble. A team of researchers led by Adam Riess, who has been investigating the expansion of the universe for years, verified that the so-called Hubble tension, as the discrepancy between different measurements is called, was not due to limitations of the Hubble Space Telescope. According to Riess, this result confirms that our cosmological models are incomplete and there may be something we don’t yet understand about the universe.
Adam Riess was one of the winners of the Nobel Prize in Physics in 2011 for the discovery of the acceleration of the universe’s expansion. Since then, he and many other researchers have been trying to find an explanation for this phenomenon. Dark energy is the working hypothesis created as a starting point but it’s not clear whether there’s a force still unknown, whether it’s a gravitational effect yet to be understood, as some claim, or there’s a different explanation.
To properly understand the problem of the acceleration of the universe’s expansion, it’s necessary to have a precise measurement and this has proven problematic. Measurements conducted with different methods have given incompatible results even taking into account the margins of error creating the so-called Hubble tension.
Astronomers hoped that the James Webb space telescope would allow them to solve this mystery but the first results published in September 2023 by a team also led by Adam Riess already confirmed the results obtained using Hubble. Now Adam Riess’s team has published results obtained with the largest sample of data available thanks to observations conducted in the first two years of Webb’s scientific mission.
Adam Riess’s team used three different methods to measure the distances of galaxies hosting supernovae to use to measure the universe’s expansion rate. This allowed precise results to be obtained in measurements based on supernovae, Cepheids, carbon-rich stars, and red giants. Once again, the results obtained with the two space telescopes have provided very similar measurements.
It was important to rule out errors due to the Hubble Space Telescope because instrumental error is a problem that exists in all fields. Measurements made with other instruments allow to understand what the margins of error may be in certain measurements, and in this case, Webb has once again confirmed the ones made with Hubble.
Many scientists are working on cosmological models based on the existence of dark energy or modified gravity to offer a real explanation for the acceleration of the universe’s expansion but for now, none of them can explain all the observations. Solving this mystery could lead to the discovery of new secrets of the universe.
