Why haven't we met aliens yet? Readers offer their own theories
Responding to an article on the puzzle of alien contact, Guardian readers propose several alternative explanations, from the lack of fossil fuels to a cosmic timing mismatch. The letters add fresh angles to the ongoing debate around the Fermi paradox.
The Guardian has published a series of reader letters responding to an article exploring why humanity has yet to encounter an advanced alien civilisation.
The fossil fuel factor
A reader from Essex argues that an overlooked factor may be access to fossil fuels. To develop the technology needed to travel beyond their home planet, a civilisation would need its own version of an industrial revolution, which in turn requires coal, followed by oil and gas. On planets lacking an easily accessible fossil fuel equivalent, intelligent life might never progress beyond a 17th-century level of technology. He adds that, from a distance, such a civilisation would be indistinguishable from a planet hosting only plant-like life.
Watching from afar
Another reader, from Birmingham, suggests that an advanced civilisation might simply be choosing to keep its distance, observing humanity and waiting to see whether it can avoid self-destruction before deciding whether to make contact.
A cosmic coincidence problem
A reader from Sheffield points out that, given the universe's age of roughly 13.8bn years, many civilisations may have arisen, flourished and vanished at different points in time. The odds of two such civilisations existing simultaneously and being able to communicate would be an enormous coincidence — meaning other civilisations may have already departed, or have yet to arrive.
A lighter take
A reader from Shoreham-by-Sea offers a more playful explanation, suggesting aliens may already have arrived but were simply too small to notice, perhaps falling down a drain or being eaten by seagulls.
