There's not a shred of evidence that Aliens have been here, or even exist. The Show Ancient Aliens is an embarrasment to science, and i used to believe them, cause it was on the HISTORY channel. But the History channel is basicly an entertainment network.

The logical question would be, why wouldnt they tell us they were out there? The most basic human questions weve had, are why are we here, and is there anybody else out there. They woulda had the same questions. Once they knew, why would they fly by, and not say anything?

Ohh... they wouldnt want us to panic... What would be the panic? and why would they care? They wouldnt have to just pop up out of nowhere, they could easily make themselves known in smaller ways first. Our radio waves program has yet to detect anything out there.

No more of a panic than the American Indians when Europe came over with boats...and weapons.

They wouldnt have to just show up one day, it could be a gradual thing.

The other thing to consider is Evolution. Not all planets evolve at the same time, or even close. Some civlizations could have started, and ended before ours even took shape.

And look at the history of Earth. 5 ice ages, Asteroids destroying our planet several times. Dinosaurs rulling. Who is to say that somewhere else, those dinosaurs, wouldnt still be living? And we discovered fire. Fire is the reason we are still here. Who is to say they discovered fire there? even if evolution was the same, the circumstances and the complex prcoess that created intelligent beings, might be unique.

It's possible we are the only game in the universe.

But if I was capable of flying to another planet, Id leave something or say something behind me. And most beings would.