How do you know you're not dead?

i think whatever actions we do have already been done light years away or it could be this way that whatever actions we do is being replayed light years away.

thats a great question. i think about those kinda things sometimes too.

Technically, you don't! You have a lot of good, rational reasons for thinking you aren't, but there is no certainty. Just like those in the movie The Matrix, most of them didn't realize the world they were living in wasn't reality at all. We can thank the philosopher Descartes for this kind of skepticism, since he was so kind :P to point it out. How do you know you're not hallucinating or dreaming right now? You don't, because we get our knowledge from our senses, and if they're wrong, then so are we. Eek! :) So all we can really do is go on our best evidence, while at the same time realizing it *might* be totally wrong.