Advanced astrophysics and everything we know so far as in documentary shows, books, articles, etcetera, etcetera. Is this real? And what I mean by my question.. Do people really believe in the existence of aliens, today, nowadays? I accept the fact that it's up to each individual to accept, learn and understand the phenomenon. But still.. I'm trying to understand this myself.
well, it's mainly up to you to study these things and form your own opinions about it... from what i've read and understand, it's very likely that Aliens probably did "seed" the Earth, and stayed for a while...
but i also see it this way - if you use mathematics as a base, there are (estimated) 400 billion stars just in the milky way galaxy (our galaxy, the one that Earth is in) alone, and another (estimated) 400 billion galaxies in the universe that we can see... just the math alone says the probability of other life is out there... but that does not mean they were ever here, just means the probability of alien life exists..
another thing to think about is the estimated age of our solar system is about 4.5 billion years old, and the estimated age of the universe is over 14 billion years old... if a life form developed 10 billion years ago, how advanced would they be if they lived for over a billion years? humans are only about 1.5 million years old, with a history of only 12,000 years... so if humans are around in a billion years from now, what would our technology be like then?