I lean towards the idea we are living in a simulation. A lot of scientists including Neil deGrasse Tyson also share this belief. Professor Nick Bostrom with the University of Oxford is a philosopher and is one of the first to hypothesize the simulation theory. An advanced race would easily have enough computing power to create a universe so realistic to us that it would be impossible for us to prove we weren't in a simulation. The programmer would put in a limiter such as the speed of light so that we would never be able to travel far enough to see the evidence of a simulation. One day we will have enough computing power to create a simulation so real the occupants won't be able to tell they're in a simulation. At this point that computer would be the size of a planet. Each simulation would at some point be able to create their own simulation and so on. Using bayesian statistics we can say that if there is only one original Universe and an infinite number of simulations than the odds we are in the original universe is 1 in whatever number you choose up to infinity.

If such an advanced lifeform existed, their universe may be very old and dark. By creating simulations they can see what the universe was like when it began and they could give it rules that would show how they became who they are. They could delete failed simulations and rewind ours to make changes we wouldn't notice.

William Poundstone wrote a book called The Doomsday Calculation and in summation he believes there is a 50/50 chance we are in the original universe. There would be the original one the only the current simulation.

To save computing power a simulation would only be real to one of us. Everyone else would only exist when the main person came in contact with them. I'm pretty sure I'm real so it sucks to be you guys lol. Just kidding.

I think this simulation needs an antivirus update.