Following on the heels of my previous posts The Goldilocks Zone and Travelers In Endless Space, I now want to consider in greater detail the possibility of intelligent life elsewhere in our galaxy (the rest of the galaxies in the universe being too far away for it to matter).
As a child, I was fascinated with the possibility of meeting beings from outer space after seeing the movie Close Encounters Of The Third Kind. At 8 or 9 years of age, I became a voracious reader of books about extraterrestrial encounters and UFO sightings. Not content with just reading about the experiences of others, I would spend many nights searching the sky for UFOs. While in retrospect, I don't believe any of the stories today that I eagerly devoured and believed as a child, I do credit my interest in UFOs with spurring my interest in reading books in general.
Eventually growing up and becoming a skeptic, my interest in alien visitors to our planet waned. I recognized that the sheer distances between us and any other planets in other solar systems was so vast as to make alien visitation to our planet highly improbable. Besides, I came to the conclusion that I still hold that if beings possessing the technology to visit our planet at will actually were visiting our planet, they would have conquered us by now. And any beings that had such capability could not be kept hidden from us by the United States government.
As for the question, "Are we alone in this galaxy?", the most famous attempt to quantify a possible answer is the Drake Equation. Below is a video of the late Carl Sagan explaining the equation.
In this interesting interview on Point of Inquiry with DJ Grothe, Jill Tarter, director of the Center for SETI Research, describes the limitations of the Drake Equation:
"On the other hand, as you go through this equation, you end up putting in guesses. So it is really not something that you can use as a tool to calculate anything meaningful. It is a wonderful way to organize our ignorance, and it is a very useful tool in that sense. But any answer you get out is just based on the biases and the guesses of the person who is using the equation and trying to get an answer."
But suppose SETI does detect a signal sent from an extraterrestrial civilization. Then what? It will obviously have a profound impact on Earth. We will know that we are not alone after all. It will cause us to reappraise ourselves and our place in the universe. The prospect of meeting or at least communicating with intelligent beings in another part of the galaxy is bound to be a cause for excitement, though I should think the wonder of the possibility will walk hand in hand with a certain sense of dread. Will these beings be benevolent or malevolent? Can we trust them and will they trust us? Of course, given the technological limitations we face with respect to space travel, if we were to find proof of an advanced alien civilization tomorrow, it could be centuries before unmanned probes could reach the source of the signals we received. And then our descendants will have to sit back and wait with anticipation.