Have you watched kids play the latest video games? Don't you wonder at how good the simulations look? At how fast they've progressed since we played packman or tetris? Does Moore's Law work in simulation quality? If it does, simulations will no doubt progress to the point that our limited beleaguered senses won't be able to distinguish simulated from real - Welcome to the Matrix.
The kicker is that these geeks of the future will, in all likelihood, industrialize the production of sense-perfect simulations. They won't produce one, they'll make many, many. So, the probability is very hight that we currently live in a simulation designed by the geeks of the future rather than in the real world - the odds are one to... how many simulations they've invented.
Yeah, alright far-fetched. Truth is, you already live in a simulation: your own. I'm not saying that there is no bedrock, common reality. I have no doubt that it is. But the fact is that the way each of us experiences this reality is the product of the simulation run by the mind software on the brain hardware. And it has gaps:
We don't need to worry much about alternative worlds. We should worry far more about our ability to pick up alternative interpretations to our own world. No matter how unlikely it sounds, every one's story is their story and there is no single story.
When someone states something outlandish or bizarre - how can we reconstruct a mental image of their brain simulation that makes them believe this? What kind of universe is this person simulating that makes their statement 100% true? We don't need to be opened-minded as much as multiple-minded.