There’s a fascinating article at Technology Review, by Nick Bostrom (previously known for his speculation that we are living in a simulation), titled “Where Are They? Why I hope the search for extraterrestrial life finds nothing.” In the article, Bostrom argues that our failure (thus far) to find life on Mars might just be a good thing – because if life was prevalent throughout the cosmos, then the silence of ET civilisations suggests that the ‘Great Filter’ which stops civilisations from reaching a highly advanced stage might be ahead of us:
This would mean that some great improbability prevents almost all civilizations at our current stage of technological development from progressing to the point where they engage in large-scale space colonization. For example, it might be that any sufficiently advanced civilization discovers some technology — perhaps some very powerful weapons technology — that causes its extinction.
I don’t agree with some of the logic in the argument, but all in all it’s certainly a piece that gets you thinking – from issues to do with evolution and life’s beginnings, through to techniques of space colonisation. And Bostrom’s “Great Filter” is such an interesting topic, it may just become a catchphrase heard in many future dialogues about the possibility of alien life.