[tjradcliffe]

There is a very general argument that we can't simulate anything remotely resembling our universe inside our universe: http://www.tjradcliffe.com/?p=1220 Short version: at the precision required for the degree of agreement we see between theory and experiment, we could simulate at most 0.5% of our universe, which simulation would not be capable of star formation because there wouldn't be enough matter in it, and a universe "above" ours that was simulating us would collapse immediately after the Big Bang because it would contain at least 200 times as much matter as ours.

The responses to that argument are two-fold:

1) start madly making up increasingly implausible auxiliary assumptions to save the claim that we might be living in a simulation

2) admit that the odds we are living in simulation are rather low, and in particular the argument that we almost certainly are thanks to recursion is extremely poor.

I favour the latter response, as the former seems to involve either claiming that the universe that is simulating us has fundamentally different physics, or that the simulation isn't actually a simulation but rather a game-like approximation that somehow gets updated with sufficient local detail that no matter what kind of experiments we do or observations we happen to make, there is special-case code for ensuring the results look like a consistent underlying physics.

Claiming the universe simulating us has fundamentally different physics requires that we drop any claims about it based on the physics of our universe, in which case it becomes untestable because anything we see may or may not be due to a simulation being run in a universe whose laws are not like our own.

Claiming the approximation is fixed up by special-case code whenever anyone thinks of doing an experiment or making an observation that might reveal the lack of a full physics engine is likewise putting the hypothesis beyond testability.

So either the simulation hypothesis is wrong, or untestable. Neither of these is very interesting.

[joaorj]

What would you say when, in a few years (or few thousand), we develop a rather crude simulation (compared to our universe) where sentient life forms emerge? And what would you say when they point out the exact same argument you did for them not being in a simulation?

The only valid answer, I think, is that nor we, nor any other lifeform, will never be able to do so. And it's impossible to predict whether we will be able to do that or not, but everything points out to the answer being yes!

But please, give me an answer I didn't think of.

PS: I completely hate the simulation argument, as it stands, as you can see in my answer to the top post.

[JoeAltmaier]

That's assuming the outer universe is anything like this one. Maybe its entirely made of concepts and math. I have simulated things, and they don't resemble our universe; why should theirs?