Magnetic monopoles are indeed speculative, but at least the theoretical foundations are pretty sound. Dirac predicted them after all, and they play nice with qu

Magnetic monopoles are indeed speculative, but at least the theoretical foundations are pretty sound. Dirac predicted them after all, and they play nice with quantum mechanics. Wormholes and the like are where you get really wild problems like time-travel, which you have to arbitrarily prevent via more speculative physics.