Everything within a ~14 billion ly "bubble" has been "observed", if the definition of observation stands as anything indirect. Gamma rays could be coming from a distant star, and they can be observed. What would be the difference between simulating everything and creating things that are about to be "observed" on the fly? Heck, interactions among particles could count as "observations" just as well as interactions between men and the universe. Aliens, if existing, would have to count as "observers" just as well as men. This would then have to apply to any living thing, and then to everything in existence. I conclude that the universe, if simulated, is simulating everything rather than just what men can see.