Twenty years ago, believing in something like simulation theory would have got no traction with mainstream science, and one would probably be laughed off the stage by accademia. The tides seem to be changing though, with people like Elon Musk and mainstream physicist like Tyson Neil Degrasse now saying that it is mathematically probable that we are living in a simulation. But I'm not quite sold yet.
So what is simulation theory?
Simulation theory is the hypothesis that the universe and everything in it, could in fact be a computer simulation. Sounds like a movie right? Like the "Matrix Reloaded", but there is some science behind it. I'm no scientist, but I'll try to break it down as best as I can. There are a few scientist that believe that one day our technology will be so advanced that we will be able to create artificial realities that are so perfect that one would not be able to distinguish it from reality. Then there's the possibility we would like our created reality better than reality and could voluntarily not want to know we are in a simulation. Which brings the point, if it is possible to do it in the future, who is to say we haven't already done it in the past, and we might now be in fact living in a simulated reality.
The hypothesis does have a lot of critics though, including myself. The universe is a very complicated place and we haven't even begun to really fully understand it. The laws of the universe as we know it seem to be confined to time and space, where as a simulation shouldn't be. But who knows maybe we don't really understand the full concept of space/time and maybe we are in a simulation. Or more likely a simulation of a simulation.
Quick shout at to Chad at "Open Your Reality". He has youtube channel that's dedicated to the subject. Where he connects the dots of simulation theory, to spirituality and old eastern religions. I will continue to be a skeptic until I see solid evidence, but his videos are pretty entertaining and interesting.