April 19, 2024

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James Webb asserts that the universe is expanding at different speeds – space

James Webb asserts that the universe is expanding at different speeds – space

Astronomers have used the James Webb and Hubble Space Telescopes to confirm one of the most bizarre theories in physics: that the universe appears to be expanding at different rates.

In 2019, measurements made by the Hubble Space Telescope (HST) confirmed the mystery. In 2023, more precise measurements from instruments on the James Webb Space Telescope (JWST) confirmed this theory.

Most, Combined measurements of the two telescopes It seems to conclusively dispel the possibility that the previous observations were caused by some kind of failure. The study published in Astrophysical Journal LettersIt suggests that there may be something very seriously wrong with the way we have understood the universe so far.

“Once you rule out the possibility of measurement error, what remains is the real and compelling possibility that we may have misunderstood the universe,” said Adam Ries, lead author of the study and a professor of physics and astronomy at Johns Hopkins University. a permit.

Currently, there are two ways to estimate the Hubble constant, the value that describes the expansion rate of the universe. The first focuses on studying tiny changes in the cosmic microwave background (CMB), the primordial remnant of the first light that formed in the universe, just 380,000 years after the Big Bang.

The second method focuses on pulsars, which are called Cepheid stars. Cepheid stars are dying variable stars, and the Sun in their outer layers expands and contracts as it absorbs and emits the star's radiation, causing the Cepheids to periodically “flash”, like distant lighthouses.

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Illustration of the expansion of the universe.

As Cepheid stars grow brighter, they pulsate at a slower rate, giving astronomers a way to measure their brightness. By comparing this brightness with observed brightness, astronomers can combine Cepheid stars, forming a “cosmic distance scale” and arriving at specific numbers for the expansion of the universe by evaluating changes in light.

According to measurements of Cepheid variables made by Rees and his colleagues, the expansion of the universe is about 74 kilometers per second/megaparsec, which is an unimaginably large value, compared to the measurements of the so-called father of quantum theory, Max Planck.

At first, scientists thought this difference was due to some measurement failure. To settle the matter, Rees and his colleagues built on previous measurements, observing an additional 1,000 Cepheid stars in five galaxies up to 130 million light-years from Earth.

After comparing this data with Hubble data, they confirmed that their previous measurements of the Hubble constant were correct.

“We have now looked at the full range of Hubble Space Telescope observations and can rule out with a high degree of certainty that some measurements are incorrect,” Rees said. “A combination of [διαστημικών τηλεσκοπίων] Webb and Hubble give us the best evidence for both. “We have found that Hubble's measurements remain reliable as we move higher on the cosmic distance scale.”

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