Do we really exist just because we are aware of our own existence? Are we sentient beings or the figments of someone else's imagination?
My favourite author, Jorge Luis Borges, once wrote a short story that deals with the issue. The title is "Las Ruinas Circulares" and if you don't know it you can read it online in English HERE.
I remember an old episode from The Twilight Zone in which the characters thought they were real but turned out to be toys "living" within a dollhouse. Not "real people" but the playthings of a giant and merciless child-god.
Borrowing a lot from previous films but also from books, especially Lewis Carroll's wonderful Alice In Wonderland, The Matrix told us that although people think they are living they might be asleep and used as batteries while the world they think they live in is a mere simulation generated by machines. The illusion is perfect, except for a few déjà-vu moments that give away glitches.
Battlestar Galactica, the miniseries, started with a Six asking a human "are you real?" and later Caprica showed us that there are many ways of being real, including the one in the V-world or in the game New Caprica City when you put the holoband on.
And now, a scientist, a NASA guy, is about to release a book based on the idea that we might be living in a simulated world that some future person would have built thanks to future super-computers...out of boredom. Interview with Rich Terrile, here. In the end, he says:
"And our simulated beings could also create simulations. What I find intriguing is, if there is a creator, and there will be a creator in the future and it will be us, this also means if there’s a creator for our world, here, it’s also us. This means we are both God and servants of God, and that we made it all. What I find inspiring is that, even if we are in a simulation or many orders of magnitude down in levels of simulation, somewhere along the line something escaped the primordial ooze to become us and to result in simulations that made us. And that’s cool."
Borges, who was blind and a poet, saw it all, before science men even started dreaming of it.