Alone in the Universe: New Indications of Our Probable Solitude

Recent results in extrasolar planet detection highlight the tremendous variety of planetary systems that exist – a diverse range of strange environments that is considerably broader than had been imagined before the first one was discovered only about fifteen years ago.  Although Earth-like planets have so far fallen below the detection threshold, it is possible to estimate whether they might exist in these or similar newly discovered systems long enough to nurture intelligent life.  The results indicate that we are alone in the universe "for all practical purposes", that is, without likely contact with an alien intelligence for at least 100 human generations, a long time frame that defines the volume of the cosmos available for communication.  This conclusion has serious implications for our self-perception, and for ethical and religious behavior.  The “misanthropic principle” is the observation that, in a universe whose physical parameters are ideally suited for intelligent life (the “anthropic principle”), the environments and situations necessary for intelligence to develop are extraordinarily rare.