I assume you've read about Bostrom's trilemma
I have. And it is predicated upon the assumption that simulated brains would be capable of consciousness. I've yet to see any demonstration of that such a thing is possible. If we don't have physical brains than what is it that's experiencing our first hand subjective experiences?
But to go one step further and say the universe does not even exist beyond a simulation created by a mathematical model, well surely that would be an explanation looking for a question to explain.
I'm not sure this is a valid critique of what the proponents of the simulation hypothesis are suggesting. Rather, what they're proposing is that the universe that we perceive is inside a computer simulation. It doesn't say the universe does not exist beyond the simulation. Our "reality" would be embedded in a deeper and truer reality.
Scientists have been able to fully map and simulate the neurons of a roach - how would their simulated roach tell that it was in a simulation?
I really feel like everyone who has taken the time to reply (and thank you guys for doing so) has genuinely missed the point which I was making. Why would we assume that simulated roaches would experience anything? Simulating a roach is not the same thing as being a roach. I don't see any evidence that simulating something in a computer would ever give the simulation the actual properties of its real life counterpart.
There's evidence that our universe has a finite "resolution" (plank scale) like you'd expect from a simulation.
We could accurately model our universe without going anywhere near the mind boggling smallness of the Planck Scale. I think one might even be able to argue that the universe having such an extraordinarily high fidelity is an indication it's not a simulation. It'd be like using a 64 bit processor to run an 8 bit game. Complete and utter overkill.
is reality Mind or Matter?
As far as I know all minds are composed of matter. Thus it would follow, if those really are the only two options, that reality is matter.
In other words, what is the nature of reality?
I suppose overly broad questions deserve overly broad answers: Reality is the interactions of space/time and energy.
This led to philosophers trying to determine what makes us human in the first place
If by "human" they mean our species - than our genes are what make us human. But if by "human" they mean something else than they need to clarify exactly what they're asking. Identity is never one thing.
how can we even prove we exist.
We start with Rene Descartes "I think therefore I am" and work from there. And we have different inputs of sensory information (sight, sound, touch, etc.) that all converge on there being an objective reality which we experience.
We live in a Empirical world, where Sight, sound, taste, touch and smell determine reality, but nobody really questions that assumption.
This is not true. Every night when we go into REM sleep we experience all kinds of sights, sounds, tastes, etc. But we don't use our dreamed experiences are actually real. Rather, we determine reality by consistency, continuity, and the ability to repeatedly demonstrate the proposed explanations of events. We DON'T think that dreams, hallucinations, or pareidolia are accurate representations of reality even though we perceive them in an identical manner to how we experience real sensory inputs.