Astro2110 – The Solar System

The likelihood of life outside of our planet is a heavily debated topic.  Overall, it seems reasonable to assume that with all of the unexplored universe around us, and the conditions required to sustain life that are not all that hard to find, there should be plenty examples of life elsewhere.  Despite this, and the overwhelming belief that we should be finding life, we are not.  There is no evidence of any life, whether intelligent or not, outside of our planet.  One explanation of this is the Fermi Paradox.  It attempts to answer the question: where are the aliens?  The Fermi Paradox proposes four arguments to explain the reason that we have not observed extraterrestrial life.  1: Aliens have not come to Earth due to the difficulty of space travel, whether it be from biological, astronomical or engineering difficulties.  2: Aliens simply have chosen never to come to Earth.  3: Advanced civilizations of aliens have arisen too recently for them to have been able to reach us yet.  4: Aliens have visited Earth in the past but for whatever reason, we did not observe them.  This paradox does do a good job of attempting to answer a very perplexing question.  That being said, most of these answers are quite unsettling as well.  Personally, I think it would be very strange if aliens have been observing us, or have even come to our planet, and we have had no idea.  I wonder which of these explanations, if any, are correct: let me know what you think is the most likely option!