Or, like the submarine, it may prove not to be; in recent years--after their appearance in science fiction--carbon nanotubes have been produced which have the strength (though not yet the length) to produce a space elevator.
Or it may prove not to be. This is like the submarine. Carbon nanotubes have been produced which have the strength (though not yet the length) to produce a space elevator. This was in recent years--after their appearance in science fiction --.