The universe is magnificently huge, and hence should have countless opportunities for life to develop, but that then begs the question, where are all the aliens? Due to the expansion of the universe being faster than the speed of life, there may be life throughout many galaxies, or even most of them, but we would simply never really know for sure do to any signal sent being outpaced in speed by the expansion of the universe, at least with our current understanding of physics. So it is practically pointless to search for life outside of our galaxy, so then where are all the Milky Way aliens? Even narrowing our search area to just 1 of 100 billion galaxies, there still should be ample opportunities for life to develop in our galaxy, where communication, however still improbable, is possible. Different studies estimate there are anywhere between 300 million to 6 billion Earth-like habitable planets in the milky way, so what gives?
There are many theories as to why life seems to be missing from the Milky Way. Perhaps they are in hiding, and only the silent civilizations survive. Perhaps they have all died out, and we simply live in a time where no other near type 1 or type 2 civilizations exist alongside is. Perhaps we are the first, pioneering the concept of intelligent life. Or perhaps billions of chances for life simply is not that many if we truly knew how complicated and rare life developing is, and we sincerely are special in this galaxy. Only time and technology will tell.
Sources:
Johann's Astronomy Blog 