This was a cool article that's kind of hard to get your head around:
'Billion' is a term that's thrown around casually in the modern financial world, but it's still a ridiculous number to conceptualize.
Therefore, to even consider the idea that any technological civilization could endure for a billion years is crazy, but I guess anything's possible. Would a line of beings lasting that long evolve into pure light consciousness?...
We could have no way of sensing them if they were some sort of weird multi-dimensional entities.
What if planet Earth has been a experimental planetary wildlife refuge constantly being observed by 'visitors' from other worlds- in whatever form they might exist? If that's the case, I can understand why it would be kept secret, because alot of people would go out of their minds.