Time Travel?

Assuming it was possible, I don't think one should ever be built. There are a ton of ethical questions to consider, and even then we don't know everything that could possibly happen. If you did go back in time, and accidentally kill off one of your grandfathers before one of your parents was born, then theoretically you shouldn't even exist.

Unless the theory of parrallel universes exists, which basically says there are an infinite number of universes, which are following a similiar path, but different things are happening on them. For example, let's say in this world, you have a choice of having coffee or tea for lunch. In this world, lets say you chose coffee. In the alternate universe, you would've chosen tea.

And that's just your decision. If we go with the parrallel universe theory again, not all events on Earth would happen the same. World War 2 for example, could've taken some very different turn of events. If someone went back in time to kill off Adolf Hitler before he became a big threat, they'd alter the course of history forever for that universe. And someone like Stalin would probably take his place anyway. Or lets say you helped him to win (by giving the Nazi's plans on how to make a working atomic weapon, which he would not have hestitated to use at all), you would be making the world worse for the people living there.

I don't think anyone has that right to tinker with history like that. While they may have good intentions (or not, depending on what they believe in), they may indirectly be responsible for something more terrible happening in the long run. Plus, if you go back (or even forward in time), you may never again end up in the same universe that you left from, and that's something you have to seriously consider (probably won't be a problem for a lowlife thug, but for others it does pose some serious problems) before you do such a thing.

Yeah, the stuff I'm saying is why time travel is such cannon fodder for stories, because if you're creative enough, you can come up with some pretty interesting stories from them. Let's just hope that they never become a reality, or if it does, the people using it are ethical enough to not interfere with the events of the world their visiting (we could have time travelers here for all we know, who are probably studying us or just on vacation and want to avoid drawing attention to themselves. Cause you know that if you claim to be a time traveler, most would say you're nuts, but the government will probably take you to Area 51 to probe you and steal your device so they can use it for themselves).

Jam it back in, in the dark.