1The discovery of even microbial extraterrestrial life would fundamentally alter our understanding of biology and our place in the cosmos.
2Is it philosophically coherent to imagine an extraterrestrial intelligence whose conceptual framework is entirely incommensurable with our own?
3The so-called 'Wow! signal' has never been definitively attributed to an extraterrestrial source, despite decades of speculation.
4Consider the ethical implications of contacting an extraterrestrial civilisation before we have established any framework for interspecies diplomacy.
5There is a growing consensus among astrobiologists that extraterrestrial organisms, if they exist, are more likely to be microbial than sentient.