The best time travel story of all time, from the grand master of hard sci-fi.
In a future with time travel, only the members of 'Eternity' (an organization/monastery across time) are allowed to travel between centuries through a ‘time shaft’ that runs between the day of its creation and eternity. Their apparent job is simply facilitating trade across time. However, their actual job, which is a closely guarded secret, is plotting and executing ‘Reality Changes’.
Reality changes are executed when world wars, nuclear apocalypses or epidemics are observed in the future centuries. For example, such an apocalypse in the 500th century might be averted by simply moving a jar a foot away in the 450th century, after careful and intensive calculations (butterfly effect /chaos theory). The monastery has a hierarchy of members to execute this. The observers go out on every century and collect data, computers analyze the data using complex equipment and technicians calculate this ‘Minimum Necessary Change’ and execute them. All reality changes, the lost inventions…etc. are documented and maintained in the archives of Eternity.
In such a setting, Asimov starts building his story, around one of the most skilful technicians in Eternity. As usual, he uses it to discuss several philosophical and psychological themes before ending with a top-notch twist. I started the book on a weekend prior to a critical 4-credit exam (Digital Communications) and couldn’t stop. I’ll leave it here before I spoil anything!
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