Still, the work is expected to launch a new era in matching the mathematical elegance of string theory to the actual world we live in.
“What they have done,” Padilla said, “is open up a new frontier to finding explicit de Sitter solutions in string theory.”
The Cutoff
The new work was inspired by a bizarre feature of quantum theory first predicted over 75 years ago.
In a vacuum, space is never completely empty. Particles pop in and out of existence, and tiny fluctuations cause quantum fields to do the same.
In 1948, the Dutch physicist Hendrik Casimir recognized that in the narrow space between two conducting plates, not all quantum fields can pop into existence. In this region, the long wavelengths get cut off. This leads to a lower energy density inside the plates than outside. The mismatch of energies creates a force that tries to push the plates together.
Mark Belan/Quanta Magazine
Bento and Montero applied this line of thinking to the process of “compactification,” in which the 10-dimensional physics of string theory becomes the four-dimensional realm we inhabit. The basic premise of compactification is that the extra dimensions should shrink down and curl up into a shape so tiny that if you were to travel along one of them, you would almost instantly come back to the starting point. The precise shape of the “manifold” that houses these extra dimensions would dictate the properties of all the particles and forces observed in nature.
In the new scenario, the space enclosed within a six-dimensional manifold takes the place of the space between Casimir’s conducting plates. Inside the manifold’s interior, fluctuations are similarly restricted, which generates a Casimir-like force. “That’s their key ingredient,” said David Andriot of France’s National Center for Scientific Research.
The researchers counterbalanced the Casimir effect with a force generated by a flux. Fluxes are standard elements in string theory compactifications. They’re made up of field lines that wind through string theory’s extra dimensions. Unlike the Casimir force, which works toward reducing the volume of the manifold’s interior, a flux creates a countervailing effect that tries to expand that volume.
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