Perhaps not you or I, but collectively wouldn't we want to try to communicate with those outside running the simulation?
I always find it fascinating to think about that, when we would be living in an simulation, they could shut the whole thing down for let's say 1 million years, turn it back on and for us it would be like nothing ever happened. Like, I sit here write this comment, in the middle of it they shut it down, wait for "a while" to power it back on, and I wouldnt even know. :)
Not that this definition of simulation matches what most people think when this question gets asked.
The answer is no you can't tell no matter how hard you try. Quantum behaviors should be enough proof that our reality can act way outside our sense of things at very small scales. Any kind of "eureka!" claims about our universe being a simulation can more easily be explained as it just being how our universe works and of course it doesn't line up with human common-sense notions of causality/physics/etc.
And not that it is even an interesting question but my take is no this is not a simulation. Way too much detail. Even if some civilization had the resources to run a simulation the size of our universe it would be a massive waste to do so. The most efficient computational system for simulating a universe with the high fidelity our universe has is to create a universe and let it evolve.
That's just as plausible as those beings waiting for us to evolve our present level of understanding, and shutting down the simulation out of disappointment that we didn't try to contact them, or hack our way out of it.
This whole discussion - not just the one we're having, but probably most discussions on this topic, here on HN and elsewhere - is the nerd equivalent of trying to figure out how many angels can dance on the head of a pin.
Wasn't that a parady of silly theological questions in general? Or maybe a "it doesn't matter" analogy?
The nerd discussion on this sim question is totally serious.
Edit: Oh. Ye. There is no upper limit on the size of a needle, so there is no upper limit on the amount of angles that can dance on its tip no matter their size, if they can intersect or what not. Anyhow, at least one, should cover any set of boundary values to the problem.
Yes, but just as likely to result in a useful outcome as trying to count angels.
What I'm trying to say is that unless someone in this discussion is maybe a high-energy particle physicist, or astrophysicist, all we're really doing is the equivalent of trying to deduce what happened to the Holy Prepuce, or what Hermione Granger's canonical ethnicity is.
Which isn't to say that it's not a fun thing to talk about; but we should recognize that we're just sitting around the fire with a couple of beers and bullshitting, and that we can't make any really definitive statements here. We're at the Greek Philosophy level of being able to talk about this stuff - all thought experiments without much actual data.
I also don't think we live in a simulation, but if we did, how can you know anything about the outside universe, leave alone its resource limitations? Perhaps what we consider to be huge and complex (our own universe) is the equivalent of a simple Conway's Game of Life to the outside world.