Why This Universe? Maybe It's Not Special—Just Probable - WIRED

To explain the cosmos’s flatness, physicists have added a dramatic opening chapter to cosmic history: They propose that space rapidly inflated like a balloon at the start of the Big Bang, ironing out any curvature.

Decades earlier, Einstein’s general theory of relativity had revealed that space and time together form a unified fabric of reality—space-time—and that the force of gravity is really the tendency for objects to follow the folds in space-time.

First, in January, while playing with toy cosmologies, they noticed that adding radiation to de Sitter space-time didn’t spoil the simplicity required to Wick-rotate the universe.

Many theorists now believe that the area of the horizon describes their ignorance of the stuff that’s fallen in—all the ways of internally arranging the building blocks of the black hole to match its outward appearance.

Ultimately, settling the question of what Boyle and Turok are counting will require a more explicit mathematical definition of the ensemble of microstates, analogous to what Jacobson and Banihashemi have done for de Sitter space.

Today, the hope is that if the researchers calculating cosmological entropy in different ways can work out exactly what questions they’re answering, those numbers will guide them toward a similar understanding of how Lego bricks of time and space pile up to create the universe that surrounds us.