The search for the rate of expansion of the universe began in the 1920s with measurements made by astronomers Edwin P. Hubble and Georges Lemaître. In 1998, this led to the discovery of “dark energy”, a mysterious repulsive force that accelerates the expansion of the universe.
Discrepancy between expansion rates
In recent years, thanks to Hubble data and other telescopes, astronomers found another twist: a discrepancy between the expansion rate measured in the local universe compared to independent observations just following the Big Bang, which predict a different expansion value.
The cause of this discrepancy remains a mystery. But the Hubble data, encompassing a variety of cosmic objects that serve as distance markers, supports the idea that something strange is going on, possibly related to new physics.
“You’re getting the most accurate measure of the expansion rate of the universe from the gold standard of telescopes and cosmic mile markers,” said Nobel Laureate Adam Riess of the Space Telescope Science Institute (STScI) and Johns University. Hopkins in Baltimore, Maryland.
“The Hubble Masterpiece”
Riess leads a scientific collaboration investigating the rate of expansion of the universe called SHOES, which stands for Supernova, H0, for the Dark Energy Equation of State. “This is what the Hubble Space Telescope was built for, using the best techniques we know to do it. This is probably Hubble’s masterpiece, because it would take another 30 years of Hubble’s life to even double this sample size,” Riess said. it’s a statement.
Article by the Riess team, to be published in the issue Special Focus from The Astrophysical Journal, reports the completion of the largest and probably last major update of the Hubble constant.
The new results more than double the previous sample of cosmic distance markers. His team also re-analyzed all the previous data, and now the complete data set includes more than 1,000 Hubble orbits.
Expansion of the universe would be slower
The expansion rate of the universe was predicted to be slower than what Hubble actually sees. Combining the Cosmological Standard Model of the Universe and measurements from the European Space Agency’s Planck mission (which observed the relic cosmic microwave background from 13.8 billion years ago), astronomers predict a lower value for the Hubble constant: 67.5 plus or minus 0.5 kilometers per second per megaparsec, compared to the SHOES team estimate of 73.
Given Hubble’s large sample size, there’s only a one-in-a-million chance that astronomers will get it wrong due to an unlucky draw, Riess said, a common threshold for taking a problem in physics seriously.
This finding is unraveling what was becoming a nice, neat picture of the dynamic evolution of the universe. Astronomers can’t find an explanation for the disconnect between the expansion rate of the local universe versus the early universe, but the answer might involve additional physics of the universe.
FEW (Europa Press, NASA, The Astrophysical Journal)
