NASA's Hubble Confirms Universe is Expanding Faster Than Expected: Data Is 'Now Impossible to Dismiss as a Fluke'

A ground-based telescope’s view of the Large Magellanic Cloud. The universe is expanding faster than expected, scientists have claimed after reviewing new measurements from NASA’s Hubble Space Telescope. NASA, ESA, Adam Riess, and Palomar Digitized Sky Survey

The universe is expanding faster than expected, scientists have claimed after reviewing new measurements from NASA's Hubble Space Telescope. Findings showed the universe is expanding about 9 percent faster than it should be—indicating that there is something missing from the cosmological models that help explain what happened after the Big Bang.

Scientists know the universe is expanding because observations showed distant objects in space—such as galaxies—are moving farther away from us. In 2011, Adam Riess, Saul Perlmutter and Brian P. Schmidt were awarded the Nobel Prize in physics for providing evidence that demonstrated the universe is expanding at an accelerating rate.

However, there has been a problem with calculating the rate of expansion. In 2016, NASA said the universe is expanding between 6 and 9 percent faster than expected. The discrepancy relates to the expected trajectory from after the Big Bang: "If we know the initial amounts of stuff in the universe, such as dark energy and dark matter, and we have the physics correct, then you can go from a measurement at the time shortly after the Big Bang and use that understanding to predict how fast the universe should be expanding today," Riess said in a statement at the time.

Measurements and observations from the early universe, using the European Space Agency's Planck satellite, suggested a certain rate of accelerating expansion. However, data from Hubble—used to calculate the 'Hubble constant,' the unit of measurement that describes the rate of the universe's expansion—does not match this.

In a study published in The Astrophysical Journal Letters, Riess and colleagues said the chance this disparity is coincidental is about one in 100,000. "This mismatch has been growing and has now reached a point that is really impossible to dismiss as a fluke. This is not what we expected," Riess, who is the Bloomberg distinguished professor of physics and astronomy at The Johns Hopkins University, said in a statement.

"This is not just two experiments disagreeing. We are measuring something fundamentally different. One is a measurement of how fast the universe is expanding today, as we see it. The other is a prediction based on the physics of the early universe and on measurements of how fast it ought to be expanding. If these values don't agree, there becomes a very strong likelihood that we're missing something in the cosmological model that connects the two eras."

hubble constant
Astronomers use three basic steps to calculate how fast the universe expands over time. NASA, ESA, and A. Feild (STScI)

In the paper, the team looked at the light from stars in the Large Magellanic Cloud, one of our neighboring galaxies. They used a newly developed technique that allowed them to observe more stars in a shorter period of time. By doing this, they were able to provide more evidence to back up the Hubble constant—and to show the universe is indeed accelerating faster than expected.

As a result, the team said there appears to be a "cosmological feature" missing from the models. What this is will be subject to further research.