Over a century ago, a Russian scientist dreamed up the idea for a space elevator. It was an audacious scheme for a cable to connect the Earth to space allowing us to access areas beyond our atmosphere with nary a shuttle mission.

Arthur C. Clarke's 1979 work, The Foundations of Paradise, introduced the idea to a broad audience, and when work with tiny but strong carbon nanotubes took off in the present century, more scientists took the idea seriously. Now, two theoretical physicists hatched a whole new way to make it work—have the space elevator rotate.

The standard way scientists have dreamed up such a contraption, like the vision that came out of a 2000 NASA workshop, interprets the phrase "space elevator" about as literally as one could: it's a car much like an elevator car, propelled by electromagnetism, ferrying people or goods to a space station or some other counterweight about 50 kilometers above Earth's surface.

An alternative version that physicists Leonardo Golubović and Steven Knudsen of West Virginia University have drawn up involves no elevator shaft at all. Rather, long looped strings rotate to create a centrifugal force that conquers gravity. Golubović explains it's like stirring a couple of coffee—if you stir too vigorously, you create too much force and the coffee flows up out of the cup. The rotating strings in this theoretical model would provide enough force to lift objects up the elevator on their own. Not content with merely creating an elevator to space, the scientists' rotating engine could even blast satellites or spacecraft into orbit. In theory.

The space elevator is one of the great dreams of the sci-fi camp that cause the dreamers to pour hours into figuring out how it might become reality. But unlike the time travel that J.J. Abrams obsesses over, a space elevator defies no theoretical physics—it's just damn hard to engineer.

Still, scientists are taking the idea seriously. A proposal to geoengineer the Earth to arrest climate change (pouring aerosols into clouds to thicken them) could be achieved via a space elevator. However, until somebody gets the audacity and permission to string carbon nanotubes out beyond our atmosphere, designing a space elevator will remain the stuff of imagination.