Alright, how's this:
Time travel is something that has been fantasised about for years. It's something which has made many appearances in popular culture and is part of many people's ultimate fantasy. Although threesomes probably factor in there somewhere too.
In the distant future, there may exist a generation of humans who decide that they want to travel back in time. This sort of enterprise, at least by our current grasp of temporal mechanics, seems almost impossible. There are many theoretical roadblocks which would potentially stop a time machine from being able to come back in time. Energy requirements, limitations of cosmic strings etc etc. Not to mention that in the entire history of our planet, there has never been a single report of someone coming back in time to see what's going on.
