I just got a vote to close as off-topic on this question with the following comment:
The question asks about the origin of a particular concept which is fantastical in nature and widely used in sci-fi and fantasy, but is not specific to a particular work or series of works.
Are such questions on- or off-topic? The help center pages don't clearly indicate whether this is on- or off-topic, and it did seem on-topic to me. Specificially, I would want to argue that it falls under this topic, but I can't say for sure.