Science fiction novels and movies are packed with far-out ideas, most often as the springboard for an action-packed adventure rather than a serious attempt to predict future trends in science or technology. Some of the most common tropes, such as accelerating a spacecraft to fantastic speeds in a matter of seconds without crushing the occupants , are just plain impossible according to the laws of physics as we understand them. Yet those very same laws appear to permit other seemingly far-fetched sci-fi concepts, from wormholes to parallel universes. Here’s a rundown of some of the sci-fi ideas that could really be done — in theory, at least.
The idea of a wormhole —a shortcut through space that allows almost instantaneous travel between distant parts of the universe — sounds like it was created as a fictional story-driver. But under its more formal name of an Einstein-Rosen bridge, the concept has existed as a serious theoretical concept long before sci-fi writers got hold of it. It comes out of Albert Einstein’s theory of general relativity, which views gravity as a distortion of space-time caused by massive objects. In collaboration with physicist Nathan Rosen, Einstein theorized in 1935 that points of extremely strong gravity, such as black holes, could be directly connected with each other. And so the idea of wormholes was born.