That scenario can never be proven though. Ideas like brain-in-a-vat or philosophies like Solipsism can never be objective, because any evidence gained would only prove to be an illusion if the scenario were true.Not really, I am saying that in an informationally based universe, intelligence is within it (the information that is) and that intelligence can understand its own existence.
An outside entity of some sort is not needed or likely IMO.
I believe it can be proved in the same way that an intelligence 'stuck' in a computer simulation could abstract the truth of its own existence and be correct. Why not?