I have spent my summer reading. One of the books I just finished was Jack Finney's Time and Again . In it Si Morley, the artist protagonist, is able to travel back in time. The premise is based on a discussion of Albert Einstein's view of time being a river. The argument goes that although we may only be able to see one section of the river at any given time, the river has not disappeared--nor has our past or future. Finney's idea is that the reason we are locked into knowing that today is today is because we are surrounded by things our senses remind us are today: newspapers, clocks, television, our furnishings, our clothing, laundry detergents, candy bars. What would happen, suggests Finney, if we surrounded ourselves with things from a previous time? Could we then step into that world, back upstream so to speak? While Si is able to do it, the author also plays with the idea of what happens when the time traveler interacts and even changes the past?
Finney's book, from 1970, has some of the same feel as Ursula LeGuinn's The Lathe of Heaven . In LeGuinn's book the protagonist George Orr is able to have effective dreams. Whatever he dreams changes everything that came before it, so no one is ever aware that things have changed--except the dreamer. Orr keeps peopling his dreams with the same people, but his relationships change without his control and each waking brings a different reality. His girlfriend Heather can be someone he's just met, his wife, or someone who's never met him.
Certainly Kurt Vonnegut played with the same kind of "time continuum" contemplation in his classic Slaughterhouse Five , where Billy Pilgrim gets jumps from past to present to future. Knowledge of his situation allowed Billy to accept the alien's "So it goes" philosophy, knowing that one never dies since time is always there in a line.
Are there other novels that take on Einstein's river? Certainly it has elements of Hermann Hesse's Siddhartha  where he contemplates the river and sees all of humanity.
Maybe all of us would like that chance to change the past, shape today into what we would like, mold tomorrow into a future we could understand.