Scientists don't know why, but "our understanding of the universe contains a lot of ignorance about two elements - dark matter and dark energy."
Astronomers have long understood that the universe is expanding - in other words, the space in between cosmic objects that aren’t bound by gravity is getting ever more vast. Then, in 1998, scientists discovered the universe’s rate of expansion is accelerating.
In the years since, researchers using the Hubble Space Telescope have observed that the current expansion rate, called the Hubble constant, is faster than what standard cosmology models estimate it should be. This mystery of inconsistent measurements is known as the Hubble tension and some postulated that this was due to inaccuracies in Hubble's measurements.
Now, a team of researchers has used data from the James Webb Space Telescope and it has confirmed Hubble’s measurements - and thus, the head-scratching continues. This latest research, published in The Astrophysics Journal, indicates the discrepancy may be caused by an as-yet unknown feature in the universe, rather than an error in telescopic readings.
The finding “suggests that our understanding of the universe may be incomplete,” says Adam Riess, an astrophysicist at Johns Hopkins University and lead author of the study. Riess co-received the 2011 Nobel Prize in Physics for discovering that the universe’s expansion is accelerating in 1998.
“Our understanding of the universe contains a lot of ignorance about two elements - dark matter and dark energy - and these make up 96 percent of the universe, so this is no small matter,” says Riess.