"I can give you over 40,000 reasons why I know that sun isn't real … I know it because the emitter's Rayleigh effect is disproportionate to its suggested size … . I know it because its stellar cycle is more symmetrical than that of an actual star … . But for all that, I'll never actually know if it looks real … if it feels real.
Before this is all over … promise me you'll figure out which one of us is the machine."
Cortana- Halo 4 (She's an AI if you didn't know that's why she can't tell if it feels or looks real.)
--------------------------------------