“Where is everybody?” wondered physicist Enrico Fermi when ruminating on the question of life in the cosmos. He reasoned that, if life’s genesis is not too difficult, the universe could be teeming with little green creatures on the many trillions of planets out there.
It’s been nearly 14 billion years since the big bang, so if some of these alien societies had become technologically advanced and spacefaring, evidence of their existence should be obvious. So why do we see no sign of them?
This apparent absence of evidence is known as the Fermi paradox. It has led to considerable head-scratching for more than half a century. Now, US astronomer Jason Wright has a new twist on it, rephrasing Fermi’s question to: “Where was everybody?” In particular, one answer could be our own solar system. He wonders if “prior indigenous technological species” arose here, and what trace might they have left behind?
The Fermi paradox has many proposed solutions: that we are truly alone in the cosmos, for example, or that Earth is kept isolated from the interstellar community until it becomes a responsible galactic citizen. The scariest possibility is the idea of a Great Filter, some inevitable sticking point that means all civilisations have a relatively short shelf life, perhaps because they develop and fall victim to self-destructive technology. In which case, on cosmic timescales, the chances of two coexisting in close proximity would be vanishingly small, and they would always appear to be alone.
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