Pastwatch

Pastwatch: The Redemption of Christopher Columbus is a science fiction novel by the American writer Orson Scott Card, published in 1996 and the first of a proposed series.

The book interweaves two stories. One is a portrait of Columbus himself, drawn from the historical record of his voyages, his calculations, his ambitions and his dealings with the courts that eventually funded him. The other belongs to a future in which historians have developed machines that can observe the past directly, allowing a discipline called Pastwatch to study events as they happened rather than as they were recorded. One of the researchers comes to believe that the arrival of Europeans in the Americas, with everything that followed for the people already living there, is a catastrophe that could have been avoided, and that her technology might permit intervention. The novel asks what it would mean to change the past deliberately, and who has the right to decide what a better outcome would be.

Card writes about the moral weight of historical knowledge, and the book's interest is in the argument about responsibility rather than in the mechanics of the time travel.