Is our universe expanding at a 'doomsday' rate? James Webb's new analysis says so

The universe is known to have been expanding from the day it existed but the rate of expansion has remained in debate till now.

James Webb Space Telescope's new measurements are now hinting that perhaps the "Hubble tension" which was believed to be causing the expansion of the universe may not have existed at all.

In a paper published in The Astrophysical Journal, University of Chicago cosmologist Wendy Freedman along with her colleagues looked into the data collected by NASA's powerful James Webb Space Telescope.

They considered the distance to 10nearby galaxiesand took measure of a new value for the rate at which the expansionism is happening presently in the universe.

They calculated the measurement of expansion of the universe at 70 kilometres per second per megaparsec which overlapped the other major method related to the Hubble constant.

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"Based on these new JWST data and using three independent methods, we do not find strong evidence for a Hubble tension," said Freedman, who is a renowned astronomer and the John and Marion Sullivan University professor in Astronomy and Astrophysics at the University of Chicago.

"To the contrary, it looks like our standard cosmological model for explaining the evolution of the universe is holding up," he added.

What is Hubble constant and how does it explain the expansion of the universe?

Since 1929 when the measurement was made of stars of the most distant galaxies, which were moving away from Earth at a speedy rate in comparison to the nearby galaxies, by UChicago alum Edwin Hubble (SB 1910, PhD1917) it was known that the universe is expanding.

However, scientists have always found it difficult to get the exact number of how fast the universe is expanding currently.

This number is called the Hubble constant and is important to decode the history of the universe. It is an important part of the process in which the universe is evolving over time.

"Confirming the reality of the Hubble constant tension would have significant consequences for both fundamental physics and modern cosmology," said Freedman.

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Since the Hubble constant is difficult but important to determine, scientists are trying to test them with the help of different methods to make sure the exact numbers are achieved.

Scientists have tried to study the remnant light after the Big Bang, which is called thecosmic microwave background, to determine the numbers.

Using this method, the best estimate of the Hubble constant found by the scientists is 67.4 kilometres per second per megaparsec.

The second method adopted by them is measuring the expansion of galaxies present in Earth's local cosmic neighbourhood with the help of stars whose brightnesses have been identified.

Earlier, when this method was used to determine the Hubble constant, measurements came closer to 74 kilometres per second per megaparsec.

(With inputs from agencies)