World's most powerful space telescope measures expansion rate of the universe

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A team of researchers have used NASA and the European Space Agency's James Webb Space Telescope, the world's most powerful space telescope, to attempt to uncover the mystery surrounding how fast the universe is expanding.

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Scientists have been battling to solve what is widely referred to as the "Hubble tension," which is the conflicting answer between the two methods that can be used to measure the expansion rate of the universe. Observations of distant supernovae suggest a lower rate of expansion, while measurements of cosmic objects closer indicate a higher rate of expansion.

The lack of a unified result causes the "Hubble tension," which refers to the astronomer Edwin Hubble, who discovered distant objects appear to be moving away from Earth faster than closer objects. For example, when measuring the Cosmic Microwave Background, the signature leftover after the Big Bang, astronomers land on a Hubble constant of 67.4 kilometers per second per megaparsec while measuring the brightness of nearby galaxies, the number jumps up to 74 kilometers per second per megaparsec.

A team out of the University of Chicago, led by cosmologist Wendy Freedman, dove into Webb telescope data and applied three measurement methods, and all three yielded the same result of 70 kilometers per second per megaparsec.

"To cross-check their results, they used three independent methods. The first uses a type of star known as a Cepheid variable star, which varies predictably in its brightness over time. The second method is known as the "Tip of the Red Giant Branch," and uses the fact that low-mass stars reach a fixed upper limit to their brightnesses. The third, and newest, method employs a type of star called carbon stars, which have consistent colors and brightnesses in the near-infrared spectrum of light. The new analysis is the first to use all three methods simultaneously, within the same galaxies," reads the press release

"Getting good agreement from three completely different types of stars, to us, is a strong indicator that we're on the right track," said Freedman