Tau Zero is a hard science fiction novel by American writer Poul Anderson. The novel was based upon the short story "To Outlive Eternity" appearing in Galaxy Science Fiction in 1967. It was first published in book form in 1970.
The book is regarded as a quintessential example of "hard sci-fi", as its plot is guided by technology. It was nominated for the Hugo Award for Best Novel in 1971.
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