Universe could loop back on itself, study of ancient light suggests

An ant crawling straight along the equator of a globe will eventually circle back to its starting point. A new study of the oldest light there is, the cosmic microwave background (CMB), suggests that—similar to the globe—on the biggest scales the universe curves back on itself in a “closed” geometry, New Scientist reports. Other researchers are skeptical, however. The new claim, published this week in Nature Astronomy , rests on observations of how the gravity of the galaxies distorts or “lenses” the mottled CMB. However, other analyses of the same phenomena support a flat universe. Still, if the claim stands up, it would harpoon the concept of inflation, the idea that in the first infinitesimal fraction of a second, the newborn universe underwent an exponential growth spurt that stretched it flat as a billiard table.