Timescape is a 1980 science fiction novel by Gregory Benford that won the Nebula, British Science Fiction Association, and John W. Campbell Memorial Awards. The story is a "hard science fiction" novel that alternates between two time periods: 1998, where scientists are trying to send a message to the past to avert an ecological disaster, and 1962, where a young physicist named Gordon Bernstein discovers the interference in his experiments. The novel is praised for its blend of detailed character development and scientific concepts like tachyons and time travel. 
Plot summary
1998: Earth is facing an ecological crisis, and a group of scientists is attempting to send a message to the past using theoretical tachyon technology. Their goal is to warn humanity and change the course of history to prevent the catastrophe. 
1962: Gordon Bernstein, a young physicist in California, notices strange interference in his lab experiments. He gradually uncovers the truth: the interference is a message from the future, sent by scientists trying to alter the past. 
Themes: The novel explores the subculture of scientists, their relationships, and the pressures they face from academia and government. It also delves into the scientific and ethical challenges of time travel and the potential for changing the future.