Nobel Prize winner now questions the standard model of the universe, says it might be wrong

About 30 years ago, scientists made a discovery that changed what we thought we knew about the universe. They discovered that our universe was expanding instead of slowing down. And this expansion, in fact, was speeding up. But the story didn't end there. 

Ever since, two competing measurements of how fast the universe is growing have refused to match, and the gap between them just won't close.

Back in the late 1990s, two astrophysicists led separate research teams to study the distant exploding stars called Type Ia supernovae. One was Adam Riess, and the other was led by Saul Perlmutter. They expected to find that gravity was slowing the expansion of the universe.

But instead, what they found was actually the opposite. The expansion was speeding up, and it was caused by a mysterious energy, which they named dark energy. For this, Riess, Perlmutter, and their fellow researcher Brian Schmidt shared the 2011 Nobel Prize in Physics.

In the image, from left to right are Brian P. Schmidt, Saul Perlmutter and Adam Riess.

The problem was that they were unable to agree on how fast the universe was actually expanding. To calculate this, the Planck satellite used the ΛCDM model along with light left over from the early universe. This gave them an expansion rate of 67 kilometers per second per megaparsec. 

But Riess's own team used a different approach. They measured the distance between nearby galaxies and found that the expansion was about 73 kilometers per second per megaparsec. This mismatch is often called the “Hubble tension”.

The researchers believed that as measurements became more exact, the two numbers would eventually align. But the gap has only gotten harder to explain as scientists find more data. This has caused the researchers to question the standard models of our universe. 

The Dark Energy Spectroscopic Instrument (DESI) maps millions of galaxies and quasars to see how the universe has expanded over billions of years. Its own data matched the previous model just fine. But in March 2025, researchers found that dark energy might not stay constant after all. It could be changing over time.

"The discrepancy between the observed expansion rate of the universe and the predictions of the standard model suggests that our understanding of the universe may be incomplete," said Nobel laureate and lead author Adam Riess, a Bloomberg Distinguished Professor and professor of Physics and Astronomy at Johns Hopkins University. 

"With two NASA flagship telescopes now confirming each other's findings, we must take this [Hubble tension] problem very seriously—it's a challenge but also an incredible opportunity to learn more about our universe,” he further added.