David Shiga writes "Astronomers have identified many objects out there that they think are black holes. But could they be portals to other universes called wormholes, instead? According to a new study by a pair of physicists, we wouldn't be able to tell the difference. They have discovered that wormholes with the right shape would look identical to black holes from the outside. But while a trip into a black hole would mean certain death, a wormhole might spit you out into a parallel universe with its own stars and planets. Exotic effects from quantum physics might produce wormholes naturally from collapsing stars, one of the physicist says, and they might even be produced in future particle accelerator experiments."