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https://www.quantamagazine.org/string-th...-20260114/
INTRO: In 1998, astronomers discovered dark energy. The finding, which transformed our conception of the cosmos, came with a little-known consequence: It threw a wrench into the already daunting task of finding a version of string theory that describes the universe we live in.
Dark energy is a “positive” energy that causes our universe to expand at an accelerating rate. But the best-understood models of string theory describe universes with energy that is either negative or zero.
Of the various criticisms made of string theory through the years — that it only works in a 10-dimensional universe, that its fundamental constituents, tiny strings, are too small to ever be observed — this was perhaps the most troubling. String theory appeared to be useful only for describing a universe with a negative “anti-de Sitter” geometry, whereas we live in a universe with a positive “de Sitter” geometry.
Then last year, two physicists offered a stripped-down but precise formula for how string theory could give rise to a universe similar to ours(opens a new tab) — a de Sitter universe undergoing accelerated expansion.
“It is the very first example [from string theory] of an explicit de Sitter space,” said Thomas Van Riet of KU Leuven in Belgium.
The new work, by Bruno Bento and Miguel Montero of the Institute for Theoretical Physics in Madrid, describes a universe with a dark energy that should weaken over time — a result that matches preliminary cosmic observations from the past few years.
But the universe they describe is not exactly like ours. While their original hope was to reduce the high-dimensional world of string theory to our own four-dimensional world, they ended up with an extra dimension. “What they have found is a 5D de Sitter solution, and we don’t live in 5D,” said Antonio Padilla of the University of Nottingham.
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.” (MORE - details)
INTRO: In 1998, astronomers discovered dark energy. The finding, which transformed our conception of the cosmos, came with a little-known consequence: It threw a wrench into the already daunting task of finding a version of string theory that describes the universe we live in.
Dark energy is a “positive” energy that causes our universe to expand at an accelerating rate. But the best-understood models of string theory describe universes with energy that is either negative or zero.
Of the various criticisms made of string theory through the years — that it only works in a 10-dimensional universe, that its fundamental constituents, tiny strings, are too small to ever be observed — this was perhaps the most troubling. String theory appeared to be useful only for describing a universe with a negative “anti-de Sitter” geometry, whereas we live in a universe with a positive “de Sitter” geometry.
Then last year, two physicists offered a stripped-down but precise formula for how string theory could give rise to a universe similar to ours(opens a new tab) — a de Sitter universe undergoing accelerated expansion.
“It is the very first example [from string theory] of an explicit de Sitter space,” said Thomas Van Riet of KU Leuven in Belgium.
The new work, by Bruno Bento and Miguel Montero of the Institute for Theoretical Physics in Madrid, describes a universe with a dark energy that should weaken over time — a result that matches preliminary cosmic observations from the past few years.
But the universe they describe is not exactly like ours. While their original hope was to reduce the high-dimensional world of string theory to our own four-dimensional world, they ended up with an extra dimension. “What they have found is a 5D de Sitter solution, and we don’t live in 5D,” said Antonio Padilla of the University of Nottingham.
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.” (MORE - details)