The Gods Themselves by Isaac Asimov

In the year 2100, the invention of the Electron Pump - an apparently inexhaustible supply of free energy - has enabled humanity to devote its time and energies to more than the struggle for survival, finally breaking free of the Earth. But there is no such thing as a free lunch......

It was time for a "golden age" from this years list and here it is, also a nice short one for the summer weather (I hope we'll be having).