Perhaps the cosmos teems with life, even complex life; on the other hand, our Earth could be unique among the billions of planets that surely exist. That would be depressing for the searchers. But it would allow us to be less cosmically modest — Earth, though tiny, could be the most complex and interesting entity in the entire Galaxy — and its fate of cosmic and not merely terrestrial significance. . So let me conclude by focusing back closer to here and now. Even in the 'concertinered' timeline that astronomers envisage -- extending billions of years into the future, as well as into the past -- this century may be a defining era. The century when humans jump-start the transition to electronic (and potentially immortal) entities, that eventually spread their influence far beyond the Earth, and far transcend our limitations. Or -- to take a darker view — the century where our follies could foreclose the immense future potential. We fret unduly about small risks — air crashes. carcinogens in food, low radiation doses, etc. But I’s argue that we’re in denial about some newly emergent threats, which may seem improbable but whose consequences could be globally devastating. Some of these are environmental, others are the potential downsides of novel technologies. So how can those of us concerned about these issues — and inspired by Carl Sagan’s long-term vision — influence policy-makers? The trouble is that even the best politicians focus mainly on the urgent and parochial — and getting re-elected. This is an endemic frustration for those who’ve been official scientific advisors in governments. . To attract politicians’ attention you must get headlined in the press , and fill their in-boxes. So scientists can have more leverage indirectly -- by campaigning, so that the public and the media amplify their voice. Carl was of course ta preeminent exemplar of the concerned scientist — and had immense influence through his writings. broadcasts and lectures and campaigns..