“All the world’s a stage…,” Shakespeare wrote, and physicists tend to think that way, too. Space seems like a backdrop to the action of forces and fields that inhabit it but space itself is not made of anything—or is it? Lately scientists have begun to question this conventional thinking and speculate that space—and its extension according to general relativity, spacetime—is actually composed of tiny chunks of information. These chunks might interact to create spacetime and give rise to its properties, such as the concept that curvature in spacetime causes gravity. If so, the idea might not just explain spacetime but might help physicists achieve a long-sought goal: a quantum theory of gravity that can merge general relativity and quantum mechanics, the two grand theories of the universe that tend not to get along. Lately the excitement of this possibility has engrossed hundreds of physicists who have been meeting every three months or so under the banner of a project dubbed “It from Qubit.”
The “it” in this case is spacetime, and the qubit (pronounced “cue-bit,” from “quantum bit”) represents the smallest possible amount of information—a computer “bit” on a quantum scale. The idea suggests the universe is built up from some underlying code, and that by cracking this code, physicists will finally have a way to understand the quantum nature of large-scale events in the cosmos. The most recent It from Qubit (IfQ) meeting was held in July at the Perimeter Institute for Theoretical Physics in Ontario, where organizers were expecting about 90 registrants. Instead, they got so many applications they had to expand to take 200 and simultaneously run five satellite sessions at other universities where scientists could participate remotely. “I think this is one of the most, if not the most, promising avenues of research toward pursuing quantum gravity,” says Netta Engelhardt, a postdoctoral researcher at Princeton University who is not officially involved in It from Qubit but who has attended some of its meetings. “It’s just taking off.”
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