I read an article about this https://en.m.wikipedia.org/wiki/Brain_in_a_vat Thinking about this myself lead to the conclusion that the amount of information that would need to be generated and maintained just for my brain would be prohibitively enormous. All the people in the world and their states and history. The combined knowledge of mankind. I started thinking about quantum mechanics though and that kind of threw off my conclusions because the state of particles is not known until you measure them, which seems like an optimization of sorts. I don’t know, but it is interesting to think about.