The theory of the multiverse speculates that every action or decision creates a split, where each possibility actually happens in a different universe. I often think about this when something dramatic happens. It is easy to think "Let this not have happened", and then imagine a world where it did not happen. I thought like this when I heard that the Columbia space shuttle had exploded on re-entry, when Prime Minister Rabin was assassinated, and, of course, on 9/11.
Recently I have been thinking about this because of a book I read (to be discussed in a future post), and today something happened that made me very aware of this way of thinking. My husband was on a train that caught fire. He was unharmed, though about a quarter of the passengers suffered smoke inhalation or were injured by broken glass or when they jumped off the train to escape. Nobody received any burns.
Along with my relief that Ivor survived a potentially serious accident, I started thinking about the universe where he died. The version of me in that universe must be thinking "Let this not have happened", and I can only hope she finds some solace in imagining my situation.
Ultimately, this way of thinking is not all that helpful. Despite the speculations of SF writers, I don't think there is any way these different universes can communicate with each other. All we can do is imagine all the alternative situations that might have happened in given circumstances. So many things could have happened differently, and there is no point in regretting that we are in our particular version of the multiverse.
The only advantage of imagining alternatives is to create some emotional distance between yourself and your situation. If you become aware that things could have happened differently (and perhaps did, somewhere), you realize this is just one version of your life, so you can be more detached about it.