Scientists confirm that space seems to be expanding faster than physics can explain, based on precise measurements of a group of galaxies located over 300 million light-years away.
The measurements are based on observing over 1,000 galaxies and analyzing 12 type Ia supernovae – stellar explosions that have a characteristic brightness and allow for the precise calculation of distances.
Researchers have found that space is expanding at a rate of 76.5 kilometers per second per megaparsec (a unit of interstellar distance measurement equal to one million parsecs). However, when measured using light remaining from the beginning of the Universe, the speed is much slower: only 67.4 kilometers per second.
"The tension is now turning into a crisis," warns Dan Scolnic from Duke University, the study's lead. "We are at a point where we are putting a lot of pressure on the models we have been using for two and a half decades and finding that things don't match up."
This difference between the two speeds is one of the biggest enigmas in modern cosmology.
To solve the mystery, scientists are looking for either an error in current calculations or a completely new physical theory.
"This could reshape the way we think about the Universe," says Scolnic. "There are still surprises in cosmology and who knows what discoveries will follow?"
Researchers have reached these conclusions using data from the spectroscopic instrument for dark energy and analyzing the spectrum of wavelengths and intensities from the studied galaxies.
The study, published in The Astrophysical Journal Letters, highlights that this issue - called the "Hubble tension" - continues to pose a major challenge for understanding the Universe.