Is this why close encounters with intelligent aliens have so far eluded us? | Letters

Readers offer their explanations for the absence of hard evidence for extraterrestrial civilisations, in response to an article by Adam Kirsch When thinking about why we have not encountered intelligent aliens yet, as Adam Kirsch does (The long read, 11 August), it seems to me that one factor gets neglected: fossil fuels. Alien life could develop intelligence on myriad planets, but to develop advanced technology that would enable them to get off‑world, they need to go through an equivalent of…