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.
So here's the proposal:
There is an observation which states that computational power doubles every 12 to 18 months. So the time between the Pentium Pro 200 and the Pentium 2 400 (for argument's sake) was about that time. Not the best example, I know, because the cycle speed of a computer isn't a true indication of it's computational power. I'm just simplifying it for the sake of… well, simplicity.
If that is the case, there will be a point in the future when time (and space) travel is possible with the use of computer simulations, without the hassle of generating more energy than the universe contains or all that tedious mucking about in hyperspace. There would exist computers which are powerful enough to simulate the entire history of the earth down to the finest detail. Users could plug in and travel to any point of time they choose and be able to experience the sights, sounds, smells and tactile experiences of someone who is living in that time. It would be completely indistinguishable to the real thing.
Further to this, it would be possible at some point for a computer to completely emulate a human being (or indeed trillions of human beings) to the point where the simulation people would think that they were real people simply living out their lives and not realise that they were part of a simulation. Doing this would make the virtual reality experience more enjoyable because you would be able to interact with people who thought they were actually living in the time you were visiting. They would even have family members you could visit and talk to.
It's also possible that at some point, everyone would have one of these computers in their home. Their very own simulation of the entire history of the earth, indistinguishable to the real thing, complete with simulated people who believe they're actually living in that simulation. Billions of them. Running constant, never ending simulations of our entire history.
So, if there are, let's say, a billion simulations of the entire history of the earth and its occupants… and a single 'real' earth and it's history… It's a billion to one chance that you and I are actually living in the real world. Statistically, we're all computer simulations of historical events, created for someone's personal entertainment.
And that someone? They're an omnipotent being with complete control over time and space in our particular universe.