ANITA did see weird particles, but not parallel Universes | by Ethan Siegel | Starts With A Bang! | Jun, 2025

The ANITA experiment found cosmic rays shooting out of Antarctica. One interpretation claims “parallel Universes,” but is that right?

For some of us, the idea of parallel Universes sparks our wildest dreams. If there are other Universes where certain events had different outcomes — where just one crucial decision went a different way — perhaps there could be some way to access them. Perhaps particles, fields, or even people could be transported from one Universe to another, enabling us to live in a Universe that’s better, in some ways, than our own. These ideas have a foothold not only in science fiction, but in theoretical physics as well, from the infinity of possible outcomes from quantum mechanics to ideas related to the Multiverse.

But do these ideas have anything to do with observable, measurable reality? Back in 2018, a claim has surfaced asserting that we’ve found evidence for parallel Universes from the ANtarctic Impulsive Transient Antenna: ANITA. It’s true: the experiment found evidence for cosmic ray particles that appears quite difficult to reconcile with only conventional physics. Then, in 2025, a follow-up study was conducted with the Pierre Auger Observatory, where a single candidate event was found that would be…