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.
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