String Theory Can Now Describe a Universe That Has Dark Energy

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…

Source