If time travel's ever going to be invented, we should already have it. Confuzzled? Here it goes.

Right, so as soon as we develop backwards time travel, I'm going to take it. Then, I'm going to go back in time to several thousand years B.C.E. And I'll give all of the knowledge of the world to the primitive people.

So there's several thousand years added to the place of our tech back in the time I come from. By the time time travel should be invented, it'll already exist. But, see, the groovy thing is that we can do this over and over and over.

Therefore, if time travel will ever exist, then we should be infinitely technologically advanced by now. Q.E.D. So there.