Say the universe is a restaurant entrée. Astonishingly, everything that we can discern on the plate, so to speak — protons, paramecia, people, planets, pulsars, you name it — altogether adds up to a mere sprig of parsley. To a cosmic garnish such as ourselves, the vast majority of the universe is invisible, an empty plate dominated by “dark” matter and a “dark” energy. The effects of these phenomena are writ large in space, yet their true natures have f…