Dark energy has become widely accepted as the main ingredient in today's cosmic soup. Arguing that "there is no dark energy," as Kolb says, is as heretical today as was advocating for its existence (in the form of Albert Einstein's cosmological constant) a decade ago. Thus it's no surprise that weblogs and university hallways are buzzing with the news of dark energy's possible demise... To most astronomers, the too-faint supernovae demonstrate that the universe's expansion is accelerating, as if it were stepping on the gas pedal after applying the brakes for billions of years. Kolb and his colleagues don't take issue with that interpretation. But when it comes to what's in the gas tank, they stand apart from the crowd. They attribute the universe's accelerating expansion not to dark energy, but to ripples in the fabric of space and time that dwarf the entire visible universe.