Was Einstein Wrong?

For decades, physicists have struggled to marry quantum mechanics.  Other forces of nature, like electromagnetic forces, can be described quantum-mechanically by the motion of photons.  But when you attempt to work out the gravitational force between two objects in terms of a quantum graviton,  you quickly run into trouble—the answer to every calculation is infinity.

But now Petr Hořava, a physicist at the University of California, Berkeley, thinks he understands the problem. It’s all, he says, a matter of time.

Einstein famously overturned the Newtonian notion that time is absolute—steadily ticking away in the background. Instead he argued that time is another dimension, woven together with space to form a malleable fabric that is distorted by matter. The snag is that in quantum mechanics, time retains its Newtonian aloofness, providing the stage on which matter dances but never is affected by its presence. These two conceptions of time don’t gel.

The solution, Hořava says, is to snip threads that bind time to space at very high energies, such as those found in the early universe where quantum gravity rules. “I’m going back to Newton’s idea that time and space are not equivalent,” Hořava says. At low energies, general relativity emerges from this underlying framework, and the fabric of spacetime restitches, he explains.

Can Hořřava gravity claim the same success? The first tentative answers coming in say “yes.”

Splitting Time from Space—New Quantum Theory Topples Einstein’s Spacetime: Scientific American.