Is it possible that millions of advanced civilizations have existed in our universe?

[Hancock's Booze]

and are now extinct? I'm not talking about current ones, I mean advanced civilizations like ours or even more advanced that probably evolved and then became extinct long before homosapiens appeared here on Earth? Like for example "A long time ago in a galaxy far far away"?

 

[The Seeker]

Well why not? Possibilities always exist, the universe is a very big place after all. We haven't the foggiest idea of our own galaxy having intelligent life somewhere. The universe is far too big not to have advanced civilizations somewhere.