No matter what anyone says, it’s definitely possible to change the past. It’s just that without a considerable amount of effort, those changes are usually for the worse.
Consider: You’ve just had a lovely meal at a great restaurant. You go to sleep that evening quite satisfied with your day. The next morning, you catch a news story about how the head chef at that restaurant was arrested for doing something untoward to the food before serving it to guests. You feel sick to your stomach, maybe even vomiting. Your previous evening is ruined, despite it happening in the past.
Sure, the actual events didn’t change. But your past changed considerably. And that’s what matters – after all, ‘the past’ is just a concept anyway. It doesn’t actually exist anywhere but in your own mind, as context for your current life. That’s why, under normal circumstances, “don’t try to change the past” is good advice. There’s nothing to change, so it’s just wasted effort.
But if you view the past this way, suddenly you realize that you can change it. You can’t change the events, but you can change the context and the framing – and thus change your present. You can’t undo a prior disaster, but by reframing it instead as a moment of growth and learning that gave you new wisdom, suddenly you’ve changed the only version of ‘the past’ that matters – the one in your mind.
The Opportunity Machine 