Universe Might Be Expanding Faster Than We Thought, Scientists Say

NASA

Astronomers just announced the universe might be expanding up to 9% faster than we thought.

It's a surprising insight that could put us one step closer to finally figuring out what the hell dark energy and dark matter are. Or it could mean that we've gotten something fundamentally wrong in our understanding of physics, perhaps even poking a hole in Einstein's theory of gravity.

Source: NASA
Source: NASA

In 2001, astronomers made the surprising discovery that the rate of expansion of the universe is actually accelerating. Things are speeding away from us in all directions faster and faster. Now it seems they've been speeding away from us even faster than our math originally suggested.

A team of astronomers calculated this new rate of acceleration by developing a technique that allowed them to measure the distance of faraway galaxies more precisely than ever before. They used the Hubble Space Telescope to measure the brightness of 2,400 stars in 19 galaxies and the distance of 300 supernovas. The team then used those two values to calculate the Hubble constant, or how quickly the universe is expanding over time. 

They arrived at a measurement somewhere between 5% and 9% faster than previously thought.

Astronomers used the brightness of Cepheid stars and the distance of Type 1a supernovas to measure how fast the universe is expanding.Source: NASA, ESA, A. Feild (STScI), and A. Riess (STScI/JHU
Astronomers used the brightness of Cepheid stars and the distance of Type 1a supernovas to measure how fast the universe is expanding.  NASA, ESA, A. Feild (STScI), and A. Riess (STScI/JHU

The new measurement means the distance between objects in the universe will double in the next 9.8 billion years.

This new rate of expansion has some profound implications if it's correct. 

For one, it could help us figure out the role that dark energy plays in the expansion of the universe. Dark energy is a mysterious force that pushes things apart. Scientists theorize that it makes up a whopping 68% of the universe. This discovery could mean that dark energy is getting more powerful over time and pushing objects apart with growing force. 

Another explanation for the discrepancy lies in dark matter. Dark matter is an invisible substance that makes up about 27% of the universe. We know it's all around us because we can see its gravitational effects, but we have yet to directly detect it. It's poorly understood, so dark matter could easily have some property we don't know about that is driving the rate of expansion. 

Source: NASA
Source: NASA

But there's a huge problem with this new measurement, too: It doesn't match the rate that scientists predicted based on what we know about the Big Bang. 

That means Einstein's theory of gravity could be wrong, or at least incomplete. 

"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," astronomer Adam Riess, lead author on the new study, said in a statement. "However, if this discrepancy holds up, it appears we may not have the right understanding, and it changes how big the Hubble constant should be today."

The study will be published in the Astrophysical Journal, but we'll need more research to confirm the results.