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How will we react when the aliens arrive?

Our most urgent preoccupation must be how to establish reliable two-way communication

Most people in a position to hold a critical opinion on the matter think that biological life is not unique to planet Earth but that it has also arisen elsewhere in the universe, including intelligent life. So, how will we react if intelligent alien life visits Earth?

Much of what is written on the subject is preoccupied with what rights we should grant our alien visitors. But it seems to me that our most urgent preoccupation must be how to establish reliable two-way communication with the aliens.

At present, we have no evidence that life exists anywhere in the universe beyond Earth. However, our understanding of the nature of life on Earth, how life might have arisen from lifeless chemicals and how it evolved through Mendelian genetics to the present day, together with the fact that there are many planets elsewhere in the universe with physical conditions similar to Earth, emboldens us to confidently predict that life has arisen and evolved in many locations throughout the universe.

Aliens will, almost certainly, look very different from us. This is only to be expected when we consider the vast variety of animal body-plans evolution has produced here on Earth; many that look quite strange to the human eye, eg octopus, Japanese spider crab, star-nosed mole, blobfish, narwhal, aye-aye, naked mole rat and many more (google the photographs).


Most of what I read concerning how we humans should react to alien visitors relates to what rights we should grant them, assuming the visitors are sentient, ie able to feel and perceive, to show awareness and responsiveness and to experience pleasure and pain. Great concern is expressed by philosophers like Peter Singer that we should extend the same rights to sentient aliens that we extend to sentient non-human earthly life.

If aliens visit Earth, at least in the medium term, they will almost certainly be far more advanced than us, having solved the problem of interstellar space travel well before we have. It is also very probable that they will not only be sentient but far more advanced technologically and far more intelligent than us humans.

So, I think it would be more appropriate for us to ponder what rights the aliens would be prepared to grant to us rather than the other way around. Also, what if the advanced alien visitors were hostile towards us. Aliens with the capacity to cross vast interstellar distances to reach Earth would almost certainly have the firepower to destroy us in any conflict.

I think the critically important thing to prepare for in anticipation of aliens arriving here is how to communicate with them – to ask them where they came from, why are they visiting us, what they want from us, etc. The fascinating 2016 sci-fi film Arrival explores this scenario – establishing a two-way conversation with 12 alien spacecraft that suddenly appeared in Earth’s skies.

If intelligent alien life exists it may well be broadcasting its existence to the rest of the universe, probably via radio waves. An organisation called Search for Extraterrestrial Intelligence (SETI) Institute has been listening for such broadcasts using giant radio-telescopes since 1985, but has detected none.

SETI Institute is now debating whether, in addition to passive listening, it should also be broadcasting (Active-SETI) our existence to the universe. Active-SETI would be a risky undertaking because we might attract the attention of hostile aliens far more technologically advanced than ourselves.

Meanwhile, there are persistent reports worldwide of unidentified flying objects (UFOs) in our skies. Many people believe some of these UFOs are alien spacecraft – the aliens are already here! This UFO phenomenon should not be dismissed as crackpot. Many strange sightings have been made, even filmed, by competent observers eg professional airline pilots. Governments have a duty to investigate these reports.

The Pentagon recently released a long-awaited 2022 Annual Report on Unidentified Aerial Phenomena (UAP) cataloguing 510 UAP reports gathered by agencies involved in the report and branches of the US military. UFOs are rebranded as UAP. The report assessed 366 of the most recent UAP reports. Twenty-six were characterised as uncrewed aircraft systems, or drones, 163 were balloons and six were airborne clutter like plastic bags.

One hundred and seventy UAP reports remain “uncategorised and unattributed”. Some of these displayed unusual flight/performance characteristics and “require further analysis”. It is good to see the US starting to take this matter seriously after years of media sensationalising UFO sightings.

William Reville is an emeritus professor of biochemistry at UCC