Is the Universe Shaped Like a Donut? The Radical Search for Cosmic Topology
If you could board a spaceship capable of flying in a perfectly straight line forever, what would happen? Common sense says you’d travel through endless galaxies, never reaching an edge, never looping back. But common sense might be wrong. The universe could be finite — and if you flew far enough, you might eventually return to where you started, having circumnavigated all of existence like a cosmic Magellan. The question of whether the universe wraps back on itself — its topology — is one of the deepest and most persistently overlooked questions in cosmology. Now, a comprehensive review from the COMPACT Collaboration, invited for publication in Nature Astronomy, lays out everything we know, everything we don’t, and the astonishing possibility that the evidence may already be hiding in data we’ve already collected.