transition might have been almost inevitable given the ‘right’ environment. We just

transition might have been almost inevitable given the ‘right’ environment. We just don’t know -- nor do we know if the DNA/RNA chemistry of terrestrial life is the only possibility, or just one chemical basis among many options that could be realized elsewhere LIFE Moreover, even if simple life is widespread, we can't assess the odds that it evolves into a complex biosphere. And, even it did, it might anyway be unrecognizably different. And, by the way, it’s too anthropocentric to limit attention to Earth-like planets. Carl Sagan and his Cornell colleague Ed Salpeter, envisaged balloon-like creatures floating in the dense atmospheres of Jupiter-like planets. We should also be mindful that seemingly artificial emissions could come from super-intelligent (though not necessarily conscious) computers, created by a race of alien beings that had already died out. Indeed I think that’s the most likely option if evolution took a similar course to what may happen on Earth. If the emergence of technology ona planet lags significantly behind what has happened on Earth then that planet would plainly reveal no evidence of ET. But life around a star older than the Sun could have had a head-start of a billion years or more. Thus it may already have ‘spawned’ the futuristic scenario — trasitioning from organic to electronic -- that I envisaged as our Earth’s post-human future. So even if SETI searches revealed some artificial emission, we’d be most unlikely to ‘catch’ alien intelligence in the brief sliver of time when it was still in organic form. I think it’s less likely be a decodable message than to be a byproduct (or even a malfunction) of some super-complex interstellar technology that could trace its lineage back to alien organic beings (which might still exist on their home planet, or might long ago have died out). I won't hold my breath, but SETI programmes are a worthwhile gamble - because success in the search would carry the momentous message that concepts of logic and physics aren't limited to the hardware in human skulls. Even if intelligence were widespread in the cosmos, we may only ever recognise asmall and atypical fraction of it. Moreover , the habit of referring to ET as an ‘alien civilisation’ may be too restrictive. A ‘civilisation’ connotes a society of individuals: in contrast, ET might be a single integrated intelligence HOUSE_OVERSIGHT_026741