If we really are alone in the universe, should we take Earth's life to other planets? Especially as we might already have the means

It’s fun to speculate about aliens (see “The human universe: If aliens exist, do they know we’re here?“). But what if there are no aliens? It’s been 65 years since Enrico Fermi first pointed out our solitude. Fermi estimated that it would take an advanced technological civilisation 10 million years or so to fill the galaxy with its spawn. Our galaxy is 10,000 times older than that. Where is everybody?

It’s not as though we haven’t been looking. Not for long, perhaps, and not very hard, but even a crude estimate suggests there should be other advanced civilisations capable of signalling over interstellar distances. And yet – nothing.

So what if we really are alone, or so isolated as to amount to the same thing? “If we think we are the only life in the universe, we have a huge responsibility to spread life to the stars,” says Anders Sandberg of the University of Oxford’s Future of Humanity Institute. “If we are the only intelligence, we may have an almost equal responsibility to spread that, too.”

NASA astronomer David Grinspoon agrees, although he hasn’t given up on finding ET yet. “We have these powers that no other species has had before,” he says. “If we are it, if we are the best the universe has got, if we are the universe’s sole repository of intelligence and wisdom and scientific insight and technology, it ups the ante quite a bit. We have a responsibility to preserve our civilisation.”

It won’t be easy. First, we need to decide where to boldly go (see diagram). We don’t know if humans can survive for any meaningful length of time …