Researchers are dumbfounded after "a fountain of high-energy particles erupting from the ice" in Antarctica appears to have provided evidence of a parallel universe.
The phenomenon, which a lead researcher says is "in pretty strong tension with the standard model of physics", was recorded by NASA's Antarctic Impulsive Transient Antenna (ANITA).
ANITA, a stratospheric balloon payload flying over Antarctica, was designed by NASA to detect cosmic-ray air showers through radio-wave signals on their way down or back up after bouncing off the ice.
It detected the 'fountain' of high-energy particles during flights in 2006 and 2014 but initially, these were dismissed as background noise or glitches.
However a closer inspection of the data in 2016 revealed it as a phenomenon resembling an "upside-down cosmic-ray shower", according to lead researcher and University of Hawai'i Physics Professor Peter Gorham.
"What we saw is something that looked just like a cosmic ray, as seen in reflection off the ice sheet, but it wasn't reflected," said Prof Gorham.
"It was as if the cosmic ray had come out of the ice itself. A very strange thing."
While the discovery itself was made many years ago, it has risen to prominence more recently as other, more palatable explanations for such a phenomenon have been ruled out.
Now, researchers believe these particles may actually be travelling back through time, indicating there is a parallel universe close to ours in which the standard laws of physics operate in reverse.
"Not everyone was comfortable with the hypothesis," Prof Gorham admitted to New Scientist.
Speaking to the University of Hawai'i, he said the phenomenon "could be an indication of some new type of physics, what we call beyond the standard model of physics".
Prof Gorham says the only way such an event could happen is if the particle changed form, passing through the Earth, and then coming back again.
While the research team is still trying to comprehend the implications of the data, they still aren't 100 percent sure the results aren't just due to some unseen malfunction in ANITA.
"We're left with the most exciting or most boring possibilities," says researcher Ibrahim Safa.