Rewinding the Universe: Numerical Relativity Tests Pre-Big-Bang Scenarios

A new Living Reviews in Relativity paper argues that fully relativistic numerical relativity—computationally evolving Einstein’s equations—could let cosmologists test pre-Big-Bang ideas (cyclic universes, bounces, the onset of inflation) by simulating highly nonuniform, strongly gravitating early universes and predicting observable signals (gravitational waves, CMB features), though such simulations are expensive and technically challenging.