New explanation for Antarctic mystery doesn't need "parallel universe"

Headlines all over the internet lately have been screaming about how scientists in Antarctica have discovered evidence of a parallel universe where time runs backwards. While we seriously wish that was true, a new study has put forward a more realistic explanation.

The story starts with a hook that would make any sci-fi writer jealous – in a remote research station in Antarctica, scientists picked up two anomalies in their experiment. They were looking for cosmic rays, so naturally they were focused on the skies above them. But nobody expected to spot two signals coming from below them, spontaneously bursting out of the ground and shooting upwards into the sky.

Scientists were understandably perplexed, and no less than 40 papers were published outlining possible explanations. Some proposed that these were indications of the long-sought dark matter. Others suggested sterile neutrinos, another elusive hypothetical particle, were to blame.

Those are pretty out-there ideas, but one in particular took the proverbial cake. It suggests that these anomalies are evidence of a universe that’s a mirror image of our own, made of antimatter, where time runs backwards.

It’s not entirely out-of-the-blue, either. The concept of an anti-universe is an implication of a well-studied theorem known as charge, parity and time reversal (CPT) symmetry. Basically, this idea says that the Big Bang should have created two universes – our own, and an anti-universe that from our point of view, extends backwards in time before the Big Bang.

Understandably, this exciting theory was the one that much of the tabloid media latched onto. But of course it’s far from the most logical or likely explanation. Now a new study has proposed a much more grounded idea.

Antarctic anomalies

ANITA has been doing that since 2006, but in 2016 and again in 2018 it picked up two unexpected signals. These had all the hallmarks of high-energy neutrinos – except they weren’t coming from space. They appeared to be shooting up out of the Antarctic ice far below.

Normally, neutrinos would have no problem with this. They don’t interact with normal matter very much, so they could shoot through the entire Earth like it’s nothing. But these were high-energy neutrinos, produced in events like supernovae, and they tend to interact with matter more often. It’s highly unlikely that they would make it all the way through the planet without touching anything, only to bump into a sensor on the other side.

Instead, the researchers say that the most likely explanation is that the signals did come from the sky above ANITA after all. They started off as high-energy cosmic rays falling from the sky, which then reflected off the snow and bounced signals back up to ANITA’s sensors.

“We think sub-surface firn is the culprit,” says Ian Shoemaker, an author of the study. “Firn is something between snow and glacial ice. It’s compacted snow that’s not quite dense enough to be ice. So, you can have density inversions, with ranges where you go from high density back to low density, and those crucial sorts of interfaces where this reflection can happen and could explain these events.”

A variation on that idea, the team says, is that the signal didn’t reflect off firn but sub-glacial lakes. It’s thought that these lakes would be spread too far apart to create the effect seen, but the team says that perhaps there are more of them down there than we currently know about.

“Whatever ANITA has found, it is very interesting, but it may not be a Nobel prize-winning particle physics discovery,” says Shoemaker. “ANITA still could have discovered something interesting about glaciology instead of particle physics, it could be ANITA discovered some unusual small glacial lakes.”

Until some extraordinary evidence comes in for the extraordinary claim of a parallel universe, we’ll put our money on reflected high-energy particles.

The research was published in the journal Annals of Glaciology.

Source: Virginia Tech