Natalie Paquette spends her time thinking about how to grow an extra dimension. Start with little circles, scattered across every point in space and time—a curlicue dimension, looped back onto itself. Then shrink those circles down, smaller and smaller, tightening the loop, until a curious transformation occurs: the dimension stops seeming tiny and instead becomes enormous, like when you realize something that looks small and nearby is actually huge and distant. “We’re shrinking a spatial direction,” Paquette says. “But when we try to shrink it past a certain point, a new, large spatial direction emerges instead.”
Paquette, a theoretical physicist at the University of Washington, is not alone in thinking about this strange kind of dimensional transmutation. A growing number of physicists, working in different areas of the discipline with different approaches, are increasingly converging on a profound idea: space—and perhaps even time—is not fundamental. Instead space and time may be emergent: they could arise from the structure and behavior of more basic components of nature. At the deepest level of reality, questions like “Where?” and “When?” simply may not have answers at all. “We have a lot of hints from physics that spacetime as we understand it isn’t the fundamental thing,” Paquette says.
These radical notions come from the latest twists in the century-long hunt for a theory of quantum gravity. Physicists’ best theory of gravity is general relativity, Albert Einstein’s famous conception of how matter warps space and time. Their best theory of everything else is quantum physics, which is astonishingly accurate when it comes to the properties of matter, energy and subatomic particles. Both theories have easily passed all the tests physicists have been able to devise for the past century. Put them together, one might think, and you would have a “theory of everything.”
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