Hubble has identified an unusual wrinkle in the expansion rate of the universe

(CNN) – Measuring the expansion rate of the universe was one of the Hubble Space Telescope’s primary goals when it was launched in 1990.

Over the past 30 years, the Space Observatory has helped scientists discover and improve this rate of acceleration, as well as discover a mysterious wrinkle that can only be solved by new physics.

Hubble has detected more than 40 galaxies that contain pulsars as well as exploding stars called supernovae to measure larger cosmic distances. These two phenomena help astronomers determine astronomical distances as mile markers, which indicated the rate of expansion.

In their quest to understand how fast our universe is expanding, astronomers already made an unexpected discovery in 1998: “dark energy.” This phenomenon acts as a mysterious driving force that is accelerating the rate of expansion.

And another development: an unexplained difference between the expansion rate of the local universe and the expansion rate of the distant universe immediately after the Big Bang.

Scientists don’t understand the paradox, but they do admit that it’s strange and may require new physics.

“The most accurate measurement of the expansion rate of the universe is obtained from the gold standard of telescopes and cosmic tilt markers,” said Adam Rees, a Nobel Prize winner from the Space Telescope Science Institute and Distinguished Professor at Johns Hopkins University in Baltimore. statment.

“That’s what the Hubble Space Telescope was built for, using the best technology we know to do it. This is probably Hubble’s greatest feat, because it would take another 30 years of Hubble’s life to double the size of this sample.”

decades of surveillance

The telescope is named after pioneering astronomer Edwin Hubble, who discovered in the 1920s that the distant clouds of the universe were actually galaxies. (died 1953).

Hubble built on the work of astronomer Henrietta Swan-Levitt, who in 1912 discovered periods of brightness for pulsars called Cepheid variables. Cepheids act as cosmic landmarks, periodically brightening and dimming in our galaxy and elsewhere.

Hubble’s work led to the revelation that our galaxy was one of many that forever changed our perspective and our place in the universe. The astronomer continued his work and discovered that distant galaxies appear to be moving quickly, suggesting that we live in an expanding universe that began with the Big Bang.

The discovery of the expansion rate of the universe contributed to granting 2011 Nobel Prize in PhysicsAwarded to Saul Perlmutter, Brian P. Schmidt, and Riess “for the discovery of the accelerating expansion of the universe through observations of distant supernovae.”

Reiss continues to lead SHOES, short for Supernova, H0, for the state dark energy equation, a scientific collaboration that investigates the expansion rate of the universe. Your team publishes an article on Astrophysical Journal Which provides the latest update to the Hubble constant, since the rate of expansion is known.

Unresolved contradiction

Measuring distant objects has created a “cosmic distance ladder” that could help scientists better estimate the age of the universe and understand its foundations.

Various teams of astronomers using the Hubble telescope have come up with a value of the Hubble constant of 73, plus or minus 1 kilometer per second per megaparsec. (A megaparsec is one million parsecs, or 3.26 million light-years.)

“The Hubble constant is a very special number. It can be used to thread a needle from the past to the present to comprehensively test our understanding of the universe. This required an impressive amount of detailed work,” says Licia Verdi, a cosmologist at the Catalan Institute for Research and Advanced Studies and the Institute of Cosmology at the University of Barcelona, ​​in a statement .

But the expected actual rate of expansion of the universe is slower than that observed by the Hubble telescope, according to astronomers using the Standard Cosmological Model of the Universe (a theory that suggests the components of the Big Bang) and measurements made by the Planck mission. European Space Agency between 2009 and 2013.

The Planck Observatory, another space observatory, was used to measure the cosmic microwave background, or residual radiation from the Big Bang 13.8 billion years ago.

Scientists on the Planck mission reached the Hubble constant of 67.5 or so, or 0.5 kilometers per second per megaparsec.

space telescope James Webblaunched in December, will be able to observe Hubble features at a higher resolution and at greater distances, which may help understand the discrepancy between the two numbers.

This presents an exciting challenge for cosmologists who previously sought to measure the Hubble constant and are now wondering what additional physics might help them unravel a new mystery about the universe.

“I don’t really care what the scaling value is specifically, but I like using it to learn about the universe,” said Reese.