I had to sleep on this one before I could review it. I agree with the negative reviews that lament how the book tanked when it turned metaphysical/quantum, but not with the ppl who despised Ruth's parts generally. The first part of the book is five stars, something I don't give to much. Compelling characters and story and meditations on the most fundamental aspects of life - death, aging, how we survive awful things that happen to us, how we live with the fact that we are forced to do awful things to live, how we grapple with deterioration of mind and body, what we sacrifice for those we love, how we live for those we love, when there truly is no option but suicide. But then the author takes this turn into wondering about time that kills the narrative and should have been a different book. It also felt to me like a way to avoid saying more about her fears of losing her mind as she aged. I loved the first part so much I'm giving it a 4 still, but it did let me down.