FOR an experiment designed to help us find evidence of other universes, it looks surprisingly modest. As Zoran Hadzibabic walks me into the lab, it feels more like a classroom, complete with linoleum floors, fluorescent lighting and a whiteboard with scribbled equations. And yet it is here, in amongst the tangle of stainless-steel chambers and brightly coloured wires set on a raised platform, that researchers are trying to replicate the primordial quantum bubbling that may have created our universe in a vast multiverse.
The idea that our universe is just one of many is among the most captivating in physics, and the logic seems sound enough, in the sense that the idea is itself an outgrowth of widely accepted theories about how the cosmos came to be what we see today. But there also happens to be zero empirical evidence for its existence – which is where Hadzibabic’s experiment at the University of Cambridge comes in.
The researchers are betting that if we can cool and manipulate potassium atoms to extremely low temperatures, when tiny bubbles should form spontaneously, we will have a proxy for the otherwise unobservable processes thought to have sired new universes. By studying those bubbles, we could glean fresh clues as to how any past collisions between our universe and others would leave a mark that we might plausibly hunt down in astronomical data.
“The absolute dream would be that there’s something in the sky that we observed which confirms what we predicted in this experiment,” says Matt Johnson, a theoretical physicist at the Perimeter Institute in Canada.
What is the multiverse?
To be clear, what …