I don't understand how enormous distances in space as well as time, and thus the likelihood that we will never make contact means we are "alone in the universe." ("Alone" as in the only life forms in the universe.) We just don't know.

I also note that some of the writers make the old fashioned differentiation between intelligent life (including animal life,) as opposed to life in general, such as microbial life or even plants. In reality, we don't really know what intelligent life is, including us. We just have a general notion based on ourselves.

I think our search for life mirrors our own technology: Early 20th century searches (for life on Mars) searched for shortwave radio signals, post WWII searches mirror the rise of radio astronomy, newly proposed searches visualize possible alien optical laser signals, and (as in Carl Sagan's book "Contact,") a signal that is basically a sent website with instructions. Others have proposed an interactive program sent as a signal, or aliens simply not signaling intentionally, but just putting out coherent signals as part of the activities of their "civilization." None of these speculations take into account what the alien life forms actually do or think if they exist. All these ideas mirror us, not extraterrestrials.

Fermi was brilliant, but his paradox question mirrors our concept of how an extraterrestrial advanced civilization should act. If we ever know of an actual extraterrestrial life form, I suspect we'll discover that it doesn't act or live the way we thought it should.

One exciting prospect is that as we learn more about the relationship between life on Earth and the chemistry of our planet and nearby worlds, we may have more tools with which to interpret the likelihood of life (like ours) elsewhere. I don't think we have enough tools to make sweeping statements yet.