Quest for the Future - A. E. Van Vogt
Quest for the Future - A. E. Van Vogt
1970's sci-fi, but with a 1950's sci-fi feel. Space travel, time travel, and multiple probabilities, all in one story.
One of those stories that, even after reading the Epilogue, my mind is still digesting the entire storyline. Very likely it'll be one of those books where it will be a fuller understanding with multiple passes of reading.
Near the end of the story, there is what I think is a little Easter Egg nod to Heinlein, in that the main character is reading a book, where the book has free sex, where anyone can have sex with anyone, when they are not busy, and everyone is polite if told no, if the no is due to being busy or not interested : )