New research led by University of Hawai’i astronomers suggests our Universe may rotate — just extremely slowly.
In shaping the Universe, gravity builds a vast cobweb-like structure of filaments tying galaxies and clusters of galaxies together along invisible bridges hundreds of millions of light-years long. This is known as the cosmic web. Image credit: Springel et al. / Max Planck Institute for Astrophysics.
“To paraphrase the Greek philosopher Heraclitus of Ephesus, who famously said Panta Rhei — everything moves, we thought that perhaps Panta Kykloutai — everything turns,” said Dr. István Szapudi, an astronomer with the Institute for Astronomy at the University of Hawai’i.
Current models say the Universe expands evenly in all directions, with no sign of rotation. This idea fits most of what astronomers observe.
But it doesn’t explain the so-called Hubble tension — a long-standing disagreement between two ways of measuring how fast the Universe is expanding.
One method looks at distant exploding stars or supernovae, to measure the distances to galaxies, and gives an expansion rate for the Universe throughout the past few billion years.
The other method uses the relic radiation from the Big Bang and gives the expansion rate of the very early Universe, about 13 billion years ago. Each gives a different value for the expansion rate.
Dr. Szapudi and his colleagues developed a mathematical model of the Universe.
First, the model followed standard rules. Then they added a tiny amount of rotation. That small change made a big difference.
“Much to our surprise, we found that our model with rotation resolves the paradox without contradicting current astronomical measurements,” Dr. Szapudi said.
“Even better, it is compatible with other models that assume rotation.”
“Therefore, perhaps, everything really does turn. Or, Panta Kykloutai!”
The team’s model suggests the Universe could rotate once every 500 billion years — too slow to detect easily, but enough to affect how space expands over time.
“The idea doesn’t break any known laws of physics,” the astronomers said.
“And it might explain why measurements of the Universe’s growth don’t quite agree.”
“The next step is turning the theory into a full computer model — and finding ways to spot signs of this slow cosmic spin.”
The findings appear in the Monthly Notices of the Royal Astronomical Society.
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Balázs Endre Szigeti et al. 2025. Can rotation solve the Hubble Puzzle? MNRAS 538 (4): 3038-3041; doi: 10.1093/mnras/staf446
