The Currents of Space
The Currents of Space is a science fiction novel by the American writer Isaac Asimov, published in 1952. It is the second (by internal series chronology) of three books labeled the Galactic Empire series, but it was the last of the three to be written. Each occurs after humans have settled many worlds in the galaxy, after the second wave of colonization that went beyond the Spacer worlds, and before the era of decline that was the setting for the original Foundation series.
Asimov stated in 1988 in the "Author's Note" to Prelude to Foundation that book #6 in the Foundation universe chronology was The Currents of Space (1952) and that it was "the first of my Empire novels." Book #7 was The Stars, Like Dust (1951), which was "the second Empire novel."
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