None. It is those disasters that shaped the world to be what it is today. I do not know much, but I do know if आप change something like that, it will have big consequences, not all good. I know the world as it is today isn't all too great, but if आप changed one of those things in history, who knows how much worse it might make it? People learn from disasters and mistakes, it is something that happens everyday. The टाइटैनिक incident itself was a lesson to us all. Though I do agree things like those are very tragic, and many innocent lives have been लॉस्ट from them, they were necessary.