Dark Matter: A Novel by Blake Crouch
A middling professor gets abducted and beat up, but not killed. When he comes to, he relies he has been out for some time. The world seems about the same, but some things are different. His house is still his, however, there is no sign of his wife or child. He discovers that he decided to focus on his work instead of getting married. His work led him to some great discoveries and positions at elite universities before going to work for a private company. There he discovered ways of traveling into different realities. However, he had been missing for some time. He realizes it was the him from the future that had abducted him and they had now swapped lives. The book alternates stories of the two lives of the same man, but focuses on the original one. (The version of himself that had abducted him is now living the laid-back family life.)
The original version of the professor is now treated as insane and involuntary committed, but escapes. He is also chased by members of his company. He teams up with a psychologist and explores alternate realities. One is a Utopian version of Chicago with high-tech L trains. Others are dystopian. The book concludes with many versions of the man encountering each other. What would happen if we could go back and see how things would turn out if we went down different paths? What if a version of us from one path went back to travel down a version of the other?
