The Data
Astronomers used Cepheid variable stars to measure distances across the Universe. These observations were used to calculate the Hubble constant, the rate of the universe's expansion.
Conflicting Measurements: This study presents a stark discrepancy between the expansion rate calculated from Cepheids and the rate predicted by the established cosmological model.
Cosmic Puzzle: This mismatch is extremely unlikely to be due to chance, suggesting a gap in our current understanding of how the universe works.
Rethinking the Model: Scientists may need to revise or find additions to the prevailing model of the universe to account for this discrepancy. The discrepancy in the measurements suggests that there's a 1-in-a-million chance the mismatch is due to measurement errors.
Using its powerful infrared vision, the James Webb Space Telescope has observed Cepheid variable stars in galaxies such as NGC 5468 below.
Cepheids
In this image of galaxy NGC 5468, located 130 million light-years from Earth, Hubble and Webb team up. Hubble pinpointed Cepheid variable stars, vital for measuring the universe's expansion rate. This data was then cross-checked with a Type Ia supernova's intense light within the galaxy. Supernovae like this allow astronomers to probe even deeper into space, extending our understanding of how fast the universe is expanding.
The Webb team have said "The simple solution to the dilemma would be to say that maybe the Hubble observations are wrong, as a result of some inaccuracy creeping into its measurements of the deep-space yardsticks. Then along came the James Webb Space Telescope, enabling astronomers to crosscheck Hubble’s results. Webb’s infrared views of Cepheids agreed with Hubble’s optical-light data. Webb confirmed that the Hubble telescope’s keen eye was right all along, erasing any lingering doubt about Hubble’s measurements."
"The bottom line is that the so-called Hubble Tension between what happens in the nearby Universe compared to the early Universe’s expansion remains a nagging puzzle for cosmologists. There may be something woven into the fabric of space that we don’t yet understand.
"Does resolving this discrepancy require new physics?" Read more
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