Evrim Yazgin
Cosmos science journalist
The universe has been growing since the Big Bang 13.8 billion years ago. But cosmologists can’t agree on how fast it is expanding.
A new study published in Monthly Notices of the Royal Astronomical Society suggests a radical new idea that might resolve this astronomical problem – perhaps the universe is spinning very slowly.
For decades, physicists using different observational methods have found 2 different answers for how fast the universe is expanding.
One method looks at distant exploding stars or supernovae to measure the distance between galaxies. This approach gives the universe’s expansion over the past few billion years. The other method uses radiation from the Big Bang to give the expansion rate of the very early universe.
Each value is different. This disagreement is known as the “Hubble tension” – referring to the Hubble constant which defines the rate of the universe’s expansion.
The new research tries to find a solution using a mathematical model of the universe.
At first, things are much as they always have been – a universe expanding in all directions. But the team added a new ingredient to the mix: rotation. And it appears to have made a big difference.
“To paraphrase the Greek philosopher Heraclitus of Ephesus, who famously said ‘panta rhei’ (everything moves), we thought that perhaps panta kykloutai – everything turns,” says co-lead author István Szapudi from the University of Hawaiʻi at Mānoa Institute for Astronomy.
“Much to our surprise, we found that our model with rotation resolves the paradox without contradicting current astronomical measurements,” Szapudi adds. “Even better, it is compatible with other models that assume rotation. Therefore, perhaps, everything really does turn.”
According to the model, the universe might be rotating once every 500 billion years. This is too slow to be easily detectable, but it would affect how space expands over time.
The new theory breaks no known laws of physics – a nice change for theoretical physicists.
The researchers will work on developing a full computer model of the rotating universe and figuring out the best methods to spot the faintest signs that our cosmos really is spinning.
