Is the universe flat and infinite, or something more complex? We can’t say for sure, but a new search strategy is mapping out the subtle signals that could reveal if the universe has a shape. Introduction Is the universe infinite, Aristotle asked in 350 BCE, “or is this an impossibility? The decision … is … all-important to our search for the truth.” The Greek philosopher opined that “the heavens” (meaning the moon, planets, sun and other stars) travel around the Earth in circles, and that a “bo...