NOVA

Seems every where I look of late there is a program on Nova or PBS about space and time travel. It is a fortuitous beginning for my adventure into plausible, past time travel possibilities. A character in my novel, The Time Key, wants to go back and fix the past. The only way imaginable I can gleam from all the ideas researched, is if he does this he will create a split in the universe due to his actions and create a second time track that he will be forever trapped on. But what about the fact that someone on the original time track will be deeply affected by this change? Will the original track change as well or does it have to stay the same right to the time we make a change by travelling back to the past?