Reviewing
The Oppenheimer Alternative in
Locus magazine, American science fiction writer
Paul Di Filippo praised Sawyer for his "magnificent job" in bringing his cast of "brainy and idiosyncratic" characters to life, "fully integrated both into their era and amongst themselves." Di Filippo was impressed with Sawyer's sensitive handling of Oppenheimer's security clearance hearings, and in particular, the book's ending, with its "poignant yet hopeful conclusion to Oppenheimer’s long, partly-selfless, partly-egocentric journey." In a review in
Amazing Stories, Steve Fahnestalk called the book, "people-oriented plausible SF". He described the historical section as "a brilliant bit of writing" that brings to life the scientists, physicists and events that led up to the
Atomic Age. Fahnestalk stated that the science fiction part of the story and the way it is introduced is "extremely clever", and he was impressed how its "pretty conundrum ... was brilliantly solved by the end of the book". In another review of the novel in
Amazing Stories, R. Graeme Cameron called the ending "the 'one impossible thing' allowed to SF writers per individual work". He said it was "the perfect solution" to saving humanity, and took the book from "alternate history into the realm of bravura science fiction extrapolation in keeping with the most daring SF concepts offered in the past."
Publishers Weekly stated that the novel's scientific and historical depth is "impressive", but complained that the "
communist paranoia" tended to interfere with the story's plot. The reviewer felt that while Oppenheimer's love life is "poorly handled", his characterization, in particular his "morals, genius, and grief" is "well done". Writing in
SF Crowsnest, GF Willmetts stated that Sawyer's depiction of the scientists and their impact on world events, closely tracks what really happened. But he called the book's ending "somewhat a spoiler". Willmetts complained that Sawyer does not explain or describe the machine used to send Oppenheimer to the past. He said, "I think what nags me the most is switching from a pending apocalypse and back into events that affected Oppenheimer in the past and his determination to remedy it", because it plays no part in saving humanity from the coming catastrophe. ==References==