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"Return from the Stars" is a science fiction novel by Stanislav Lem . He returned from a space expedition to Fomalhaut, which, due to relativistic time dilation, lasted about 10 years. During this time, 127 years have passed on Earth. Hal discovers that while he was travelling on Earth, a utopian society, unusual for an astronaut from the past, has developed, without violence and wars.

Soon, Hal learns that the new civilisation is based on a procedure called betrium, which neutralises all aggressive impulses in the human brain and strengthens the instinct for self-preservation. However, this procedure has side effects, at least from Hal's point of view. Humanity is risk-averse, and spaceflight is seen as unjustified adventurism. He and the other astronauts become aliens and even dangerous to society because they have not been betrothed. The protagonist faces a choice: to accept the values of the new society or to become an outcast...