Doomsday Book

Doomsday Book is a 1992 science fiction novel by American author Connie Willis. The novel won both the Hugo and Nebula Award, and was shortlisted for other awards, placing it among the most-honored works of science fiction in recent history. . In the novel Willis imagines a near future in which historian do field work by traveling into the past as observers. In theory, history has built-in protections to keep the past from being altered, resulting in travelers being prevented from visiting certain places or times. In such a case, a time machine will refuse to function, and no trip is possible. In the rest of the cases "slippage", a shift in the exact time target, occurs. The time-traveler enters after the target time, but the arrival point is the nearest place-and-time such that the visitor cannot cause a paradox. This may result in a significant variance from the projected place or time, in practice anything from 5 minutes to 5 years. Even if destinations in time and place are... full article at wikipedia