The data hinted that acceleration of the galaxies had changed over time, something not in line with the standard picture, according to Prof Ofer Lahav of University College London, who is involved with the Desi project.
“Now with this changing dark energy going up and then down, again, we need a new mechanism. And this could be a shake up for the whole of physics,” he says.
Then in November the Royal Astronomical Society (RAS) published research, external from a South Korean team that seems to back the view that the weirdness of dark energy is weirder still.
Prof Young Wook Lee of Yonsei University in Seoul and his team went back to the kind of supernova data that first revealed dark energy 27 years ago. Instead of treating these stellar explosions as having one standard brightness, they adjusted for the ages of the galaxies they came from and worked out how bright the supernovas really were.
This adjustment showed that not only had dark energy changed over time, but, shockingly, that the acceleration was slowing down.
“The fate of the Universe will change,” Prof Lee tells BBC News starkly.
“If dark energy is not constant and it’s getting weakened, this will change the whole paradigm of modern cosmology.”
If, as Prof Lee’s results suggest, the force that is pushing galaxies away from each other – dark energy – is weakening, then one possibility is that it becomes so weak that gravity begins to pull the galaxies back together.
“Rather than ending with a Big Rip, a Big Crunch is now a possibility.
“Which outcome wins, depends on the true nature of dark energy, for which we still do not know the answer,” says Prof Lee.
Prof Lee’s work has been checked by fellow experts and published in a respected journal of the RAS. But his claims have not gone down at all well with many senior astronomers working in the field, such as Prof George Efstathiou of the Institute of Astronomy at Cambridge University.
“I think that this is just reflecting the messy details of supernovas,” he says. “The correlation with age is not very tight, so I think it is dangerous to apply a ‘correction’. It looks weak to me.”
The mainstream view is that the Universe is still accelerating with almost unchanging dark energy.
But Prof Lee pushes back strongly on such criticisms.
“Our data is based on 300 galaxies. The statistical significance is roughly one-in-a-trillion chance of being a fluke. So, I strongly feel that already our research is very, very significant.”
