The End of Eternity is a 1955 science fiction novel by Isaac Asimov with mystery and thriller elements on the subjects of time travel and social engineering.
Its members, known as "Eternals", prioritize the reduction of human suffering at the cost of a loss to technology, art, and other endeavors, which are prevented from existing when they are judged to have a detrimental effect.
They are unable to travel to times before the 27th century, when the temporal field powering Eternity was established, the limit being known as the "downwhen terminus".
Andrew Harlan is an Eternal and an outstanding Technician, a specialist at implementing reality changes, who is fascinated by the Primitive times.
Senior Computer Laban Twissell, the Dean of the Allwhen Council, instructs Harlan to teach a newcomer, Brinsley Sheridan Cooper, about the Primitive.
Harlan confronts Twissell and explains that he has been teaching himself temporal mathematics and believes that its 23rd-century inventor, Vikkor Mallansohn, must have been helped in his discovery by someone from his future.
Harlan, enraged, breaks open the controls and changes the power output, which causes Cooper to be sent back to an unknown time, estimated to be in the early 20th century.
Twissell is aghast, but as Eternity still exists, he theorizes that it is possible to undo Harlan's damage and send Cooper back correctly for his mission.
Harlan, remembering the unhealthy interpersonal relationships between the Eternals and the sociological damage that he has seen to be done to people whose original "homewhen" had ceased to exist, agrees with her.
In December 1953, Asimov was thumbing through a copy of the 28 March 1932 issue of Time and noticed what looked, at first glance, like a drawing of the mushroom cloud of a nuclear explosion.
However, he began pondering the question of what the implications would be if there had been a drawing of a mushroom cloud in a magazine from 1932, and he eventually came up with the plot of a time travel story.
Asimov decided to turn the story into a novel, and on March 17, he left it with Walter I. Bradbury, the science fiction editor at Doubleday, to get his opinion.
For instance, the power source for the time travelers is referred to as "Nova Sol", and a link to the far future taps the energy of the exploding Sun.
The New York Times reviewer Villiers Gerson praised the novel by stating it "has suspense on every page" and "exhibits in every chapter the plot twists for which the author is famous.
However, in that story, the time-policing organization struggles in vain to prevent its own annihilation; the conclusion is that timelines in which time travel arises are unstable and cannot sustain their existence.
The "neuronic whip" from The Currents of Space and other stories in the "Empire" future is also found in The End of Eternity, again as something that had to be removed from reality.
For some time, The End of Eternity was out of print, but that was remedied with Tor Books' 2011 hardcover reissue and a recent move to various e-book formats.