If you simulate a piece of the universe you need to have computer memory bigger than the number of elementary particles in that chunk of the universe.
In your computer memory you must also keep track of the position and velocity of every elementary particle [which you can not do as proven by Heisenberg’s uncertainty principle]
You also must keep track of your computer and each and every one of its elementary particles and their position and velocity.
So you would have to have a computer that is bigger than itself and bigger than its corner of the universe (in which it is contained).
Logical contradiction. The scientist is an a$$.
You don’t have to track particles, you only have to track interactions. No video game tracks particles, they track the objects being interacted with at the lowest level they NEED to but never one bit more. And when you realize just how little people actually pay attention to details you see just how little one have to keep track of. Even though I’m striking individual keys to type this I’m not really paying attention to them, I’m slapping the keyboard and stuff is coming out, and even when I’m paying attention to the individual keys what goes on beneath it I don’t care about. So if my keyboard was part of a simulation right now the guts of it could be completely ignored by the software, all that matters is the keys are there, and hitting them has the expected results (movement, sound, stuff showing up on my screen), everything else can be black box until I do something (turn it upside down, hit it really hard, decide I’m really bored and take it apart) to interact with it. And of course meanwhile I’m not doing anything at home or with my car, so unless somebody else is interacting with them they can be ignored.
Play one of the Sims games, it’s especially instructive if you play on a machine that’s just barely up to spec. You’ll see that while they have a huge world what’s actually in memory is just the part you’re interacting with right now plus a little for anticipation. Make a big move and watch the memory cycle. You only have to have the front of the curtain in memory.
If you are simulating A universe, rather than THE universe, then you can make up any "physical laws" that you want.
For all we know, the Heisenberg Uncertainty Principle was created by a software programmer as a simplifying mechanism for the simulated universe he was creating and in which we exist.
The above comments only make sense, of course, if it is possible to be AWARE while existing inside somebody's computer simulation.