Isaac Asimov's The Gods Themselves is a significant addition to the science fiction genre. In the midst of an energy crisis, the tale outlines a future where energy has become essentially free, not simply in an economic sense, but also in an apparent violation of thermodynamics and physics. Asimov suggests the existence of parallel universes where fundamental physical properties differ such that with the exchange of specific elements, each universe can power its own brand of free energy. Needless to add, there are long term consequences for each; however, human greed and the cinematic thirst for power along with academic backstabbing serve to create a stalemate.
Furthermore, Asimov crafts a truly alien universe where there are three sexes, the Rational, the Parental, and the Emotional and portrays a unique social configuration which results in a similar to dilemma as Earth. Finally, Asimov adds a third component which is lunar colonization, along with another distinct social configuration with a desire for separation from their Earthen brethren. The solution to this impending train wreck in both universes lies in the identification of a third universe, where conditions make life impossible, for material transfer and so the exchange can favor the living universes from an energy standpoint.
As is typical for Asimov, his character development is weak, but conceptually, the idea of parallel universes where fundamental laws of physics have different constants, as well as truly alien intelligent lifeforms carries the tale.