Are you asking how this (probably not simulated) universe can function? Or are you asking about if the universe were a simulation?

@NotThatGuy Both scenarios are interesting to ponder over actually.

The universe is not implementing human-created mathematical models of the universe. The universe implements the universe. Much more computationally efficient!

Any CS grad student would know how to optimize the simulation in the same way a video game optimizes graphics by not rendering what you can't see as a player. There is no need to simulate every atom in a reaction if no human is looking too closely, just use some abstract model at the macroscopic level, or every instance of nuclear fusion in a distant star if you might just as well render it by a shiny dot. Of course the required power would still be huge, but the advantage of confusing phylosophy with SF worldbuilding is we can always handwave those details.

If the simulation hypothesis were true, then what environment would run the simulation? And why should we assume that it follows the same laws of physics as the simulation we supposedly live in?

If we accept the premise of the question - that the universe is "run" at all - how would you know how smoothly it runs? Within the universe your perception would be the same regardless.

@Barmar I'd argue it's even worse, it's more like asking how you can so efficiently simulate exactly how a glass will break by simply dropping it on the floor

@llama The point of my computer analogy is that computers do simulate things, but they also are things in their own right. A computer "simulates itself" perfectly and in real time.

hitherby-dragons.wikidot.com/…

Another version of this question is "where does the universe store all the data it needs to operate the laws of physics?"

@armand: Yes, but note that a graduate student in complexity theory might know Holevo's theorem and that BQP is no easier than P. It's reasonable to ask how a particle simulation might integrate over exponentially many terms, since the theory demands that we do it.

"without any apparent bugs" -- a bug is a mismatch between what a program does and what its author intended it to do. So you can't know this... unless perhaps you are claiming that there is a God and you know its intentions? "the difficulty scales exponentially with the number of particles" -- we know of several physical laws which limit the range of effect a particle can have (if you generalize the word "range" a little), so this exponential scaling may have an upper limit. You might even consider this a clue that we're in a simulation.

It runs on Linux.

@usul Each quark is an object that stores it's state. The universe actually spends most of it's time resolving pointer references from macroscopic entities down to subatomic particles in loops within loops that some say a man named Ezekiel actually saw.

Physics is defined by what the universe does. So there is no surprise that the universe manages to do it.

This question walks a thin line between legitimacy and anthropomorphism. I can't find any evidence of another form of life besides human beings that create simulations. I havent seen a religious text or document that mentions simulations or anything similar. That would make humans the only lifeform that creates simulations. So applying the simulation concept to the universe or an entity outside the universe seems like anthropomorphism.