If we could travel into the past, it's mind-boggling what would be possible. For one thing, history would become an experimental science, which it certainly isn't today. The possible insights into our own past and nature and origins would be dazzling. For another, we would be facing the deep paradoxes of interfering with the scheme of causality that has led to our own time and ourselves. I have no idea whether it's possible, but it's certainly worth exploring.
One of the paradoxes that makes the internet such a suggestive place is that, on the one hand, we perceive it as perpetually in motion and changing, and, on the other hand, it has this god-like immortality to it: It seems like it won't die and is not subject to decay, and that everything can be unwound, unlike present-tense experience, where you can't archive the present moment, you can't go back and read it over again. That's the fundamental hallmark of the internet.
There is a new science of complexity which says that the link between cause and effect is increasingly difficult to trace; that change (planned or otherwise) unfolds in non-linear ways; that paradoxes and contradictions abound; and that creative solutions arise out of diversity, uncertainty and chaos.
It is one of those simple but beautiful paradoxes of life: When a person feels that he is truly accepted by another, as he is, then he is freed to move from there and to begin to think about how he wants to change, how we wants to grow, how he can become different, how he might become more of what he is capable of being.