The “crisis in cosmology,” sparked by differing measurements of the universe’s expansion, may be nearing a resolution thanks to the James Webb Space Telescope.
New Insights From the James Webb Space Telescope But new measurements from the powerful James Webb Space Telescope seem to suggest that there may not be a conflict, also known as the ‘Hubble tension,’ after all.
In a paper submitted to the Astrophysical Journal, University of Chicago cosmologist Wendy Freedman and her colleagues analyzed new data taken by NASA’s powerful James Webb Space Telescope.
“Confirming the reality of the Hubble constant tension would have significant consequences for both fundamental physics and modern cosmology,” explained Freedman.
This apparent mismatch has become known as the ‘Hubble tension.’ Enter the James Webb Space Telescope The James Webb Space Telescope or JWST, offers humanity a powerful new tool to see deep into space.
There might not be a “Hubble tension,” according to a University of Chicago study that measured the rate of expansion of the universe.
The James Webb Space Telescope may be helping to resolve the “crisis in cosmology,” which was brought about by inconsistent estimates of the universe’s expansion. Scientists have analyzed new data that may indicate that the Hubble tension is not as bad as previously believed. This could imply that the universe continues to fit our current model accurately.
The Argument over the Rate of Universe Expansion.
Though astronomers continue to disagree on the precise rate of expansion, we still know a great deal about our universe. More than 20 years have passed since the two main methods for calculating this value, sometimes referred to as the “Hubble constant,” produced divergent results. As a result, some have begun to question whether our current understanding of the universe is incomplete.
Fresh Findings With the James Webb Space Telescope.
The “Hubble tension,” as it is called, may not actually exist, according to recent measurements made with the mighty James Webb Space Telescope.
University of Chicago cosmologist Wendy Freedman and her colleagues examined fresh data obtained by NASA’s potent James Webb Space Telescope in a paper that was submitted to the Astrophysical Journal. They measured the separation between ten nearby galaxies and determined a new value for the current expansion rate of the universe.
They overlap the other major method for the Hubble constant with their measurement of 70 km/s per megaparsec.
Renowned astronomer and John and Marion Sullivan University Professor in Astronomy and Astrophysics at the University of Chicago Freedman stated, “Based on these new JWST data and using three independent methods, we do not find strong evidence for a Hubble tension.”. Instead, it appears that the standard cosmological model that we used to explain how the universe evolved is still valid. “.
Tension in Hubble?
When Edwin Hubble (SB 1910, PhD 1917), a UChicago alum, measured star distances and found that the farthest galaxies were traveling away from Earth more quickly than the closer ones, in 1929, we knew that the universe was expanding over time. However, determining the precise rate at which the universe is expanding right now has proven to be surprisingly challenging.
This value, sometimes referred to as the Hubble constant, is crucial to comprehending the origins of the universe. It is central to our theory of the universe’s long-term evolution.
According to Freedman, “confirming the existence of the Hubble constant tension would have significant consequences for both fundamental physics and modern cosmology.”.
Various Methods of Measurement.
Scientific methods are employed to ensure the highest level of accuracy in these measurements, given their significance and difficulty.
One important strategy is to examine the cosmic microwave background, or leftover light from the Big Bang. 67.4 kilometers per second per megaparsec is the most accurate estimate of the Hubble constant that can currently be obtained using this method.
Freedman focuses on the second main technique, which involves using stars with known brightnesses to directly measure the expansion of galaxies in our local cosmic neighborhood. The stars appear progressively fainter at larger and greater distances, much like automobile lights do when they are far away. The rate of expansion of the universe can then be determined by measuring the distances between galaxies and their speed of motion away from us.
A higher value for the Hubble constant—closer to 74 km/s per megaparsec—was obtained in the past using this technique for measurements.
The Enigma of Hubble Tension.
Given the magnitude of this discrepancy, some scientists theorize that our standard model of the universe’s evolution may be lacking some important information. One approach examines the early universe, while the other focuses on the present era. This suggests that the universe underwent a significant alteration over time. The “Hubble tension” is the term coined to describe this apparent mismatch. “.
Introducing the James Webb Space Telescope.
Humanity now has a powerful new tool to see far into space thanks to the James Webb Space Telescope, or JWST. The Hubble Telescope’s replacement, which was launched in 2021, has expanded our understanding of the universe by providing previously unobserved details about distant worlds, taking incredibly sharp pictures, and gathering vast amounts of data.
In order to measure the expansion rate of the universe, Freedman and her colleagues used the telescope to measure ten nearby galaxies.
They employed three different approaches in order to cross-check their findings. In the first, a star type called a Cepheid variable star is used, which has predictable brightness variations over time. The second technique, called the “Tip of the Red Giant Branch,” makes use of the fact that the brightness of low-mass stars has a maximum. The third and most recent technique uses carbon stars, a class of star with uniform near-infrared color and brightness. Throughout the same galaxies, the new analysis is the first to apply all three techniques at once.
Reevaluating the Hubble Constant.
In every instance, the values fell within the 67.4 km/s margin of error for the value obtained using the cosmic microwave background method.
According to Freedman, “having solid agreement from three very different kinds of stars is a strong indicator that we’re on the right track.”.
According to co-author of the study Barry Madore, visiting faculty at the University of Chicago and member of the Carnegie Institution for Science, “further observations with JWST will be critical for confirming or refuting the Hubble tension and assessing the implications for cosmology.”.
Wendy L. is the author of “Status Report on the Chicago-Carnegie Hubble Program (CCHP): Three Independent Astrophysical Determinations of the Hubble Constant Using the James Webb Space Telescope.”. Barry F. Freedman. Taylor J., Madore, In Sung Jang. Hoyt, Julia J. Lee and Kayla A. Owens, August 12, 2024, Cosmology and Nongalactic Astrophysics, Astrophysics.
the arXiv:2408.06153.
Besides Taylor Hoyt (PhD’22, currently at Lawrence Berkeley National Laboratory), UChicago graduate students Kayla Owens and Abby Lee, and research scientist In Sung Jang were also authors on the paper.
NASA is the sponsor.
