A train is a form of rail transport consisting of a series of vehicles that usually runs along a rail track to transport cargo or passengers. Motive power is provided by a separate locomotive or individual motors in self-propelled multiple units. Although historically steam propulsion dominated, the most common modern forms are diesel and electric locomotives, the latter supplied by overhead wires or additional rails. Other energy sources include horses, rope or wire, gravity, pneumatics, batteries, and gas turbines. Train tracks usually consists of two, three or four or five rails, with a limited number of monorails and maglev guideways in the mix. The word ‘train’ comes from the Old French trahiner, from the Latin trahere ‘pull, draw’. A wormhole is a hypothetical topological feature that would fundamentally be a shortcut through spacetime. A wormhole is much like a tunnel with two ends, each in separate points in spacetime. Which train will you ride?