[calex59]

Yeah, but you know what? They haven't invented time travel or someone would have come back to see us.

On the other hand, maybe all the BS going on in the world today are people who have come back in time who want to alter the future!/SAR

I really don't like the idea of machines being able to think, it opens up to many possibilities of machines running amok.

[Erasmus]

If we aren’t being visited by travelers from the future, it could be due to:

1. Travel back in time is not possible; or,
2. For the human race, there is no future.

[Immerito]

...or they’re already here, working covertly.