Can computers simulate all the laws, even theoretically? We don't have a final theory / unification of all the physics frameworks, so I'm not sure if that claim can be made. Ex: the standard model and gravity.
I'm assuming that you don't need to model e.g. quantum gravity effects to faithfully simulate a brain. Probably chemistry is enough *shrug.
Some people think that consciousness is related to quantum mechanics, but the laws of quantum mechanics can be simulated with a Turing machine so that doesn't necessarily change the story.
We know the physics at which the brain operates, a deeper uncomputable foundation theory isn’t going to change that. An analogy is we know if you drop a ball it falls down, knowledge of some deeper quantum gravity theory isn’t going to mean ball’s actually fall up.
Some people think that consciousness is related to quantum mechanics, but the laws of quantum mechanics can be simulated with a Turing machine so that doesn't necessarily change the story.