We should note that the actual results showed that things were slowing down at first, but for the last five billion years, something has been pushing the bits of the exploding universe faster and faster away from one another. This driving force that’s making the universe bigger at an increasing rate is what physicists call dark energy. We can’t see it (that’s why it’s “dark”), and it’s pushing everything apart (so they call it an “energy”). And it’s such a major force that it’s estimated to represent 68 percent of the total mass and energy in the universe.
