Part 12/23:
He describes dark energy as a uniform "steam" filling the cosmos, exerting a repulsive force that causes galaxies to rush away faster over time. This acceleration might be due to a form of repulsive gravity emerging from quantum fields—a concept consistent with Einstein’s math and supported by observational data like gravitational wave detection.
The universe's early moments are probed through inflation theory: a rapid exponential expansion driven by repulsive gravity that smoothed out initial fluctuations, giving rise to the cosmos we observe. Greene notes that some regions in the larger multiverse could have different physical laws or properties, leading to an array of diverse realities, many vastly different from our own.