Description: Use of tachyons to warn scientists of the past about an upcoming disaster. Winner of the 1980 Nebula and British Science Fiction Awards and the 1981 John W. Campbell Memorial Award for Best Science Fiction Novel. // 1980 novel by science fiction writer Gregory Benford (with unbilled co-author Hilary Foister, Benford's sister-in-law, who is credited as having "contributed significantly to the manuscript").[1] It won the 1980 Nebula and British Science Fiction Awards,[2] and the 1981 John W. Campbell Memorial Award for Best Science Fiction Novel.[3] The novel was widely hailed by both critics of science fiction and mainstream literature for its fusion of detailed character development and interpersonal drama with more standard science fiction fare such as time travel and ecological issues.[4]