THE CONFIRMATION OF ALIEN LIFE ON A PLANET 124 LIGHT-YEARS AWAY SHOULD WORRY US ALL, – MATT RIDLEY 

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Published on: April 17, 2025

I now expect to see the existence of extraterrestrial life confirmed in the next few years. When it happens, put down your phone, look up from your work, walk away from your routine and let the moment sink in. Then we can go back to arguing about pronouns and tariffs.

We are not there yet but it looks getting increasingly likely we will find alien life. The discovery announced this week by Nikku Madhusudhan and his colleagues at Cambridge University of what looks suspiciously like a “biosignature” of life in the atmosphere of a planet called K2-18b orbiting a star 124 light-years away may or may not prove to be a key moment.

It will be a fifth Copernican moment when it happens: scientists putting another dent in human self-importance. They showed that the earth orbits the sun, not vice versa (Nikolaus Copernicus); that we are just another species of animal (Charles Darwin); that we use the very same genetic code as a cabbage (Francis Crick); that far from being sophisticated creatures, we have the same number of genes, indeed mostly the very same genes, as a mouse (the Human Genome Project).

The new evidence comes from the James Webb Space Telescope, which started a couple of years ago looking at distant planets with sufficient resolution to identify the chemicals in their atmospheres. In this case, they have found fairly strong hints of dimethyl sulphide (DMS) and/or dimethyl disulphide, neither of which are generated on earth except by marine plankton.

It was my old friend James Lovelock, the Gaia theorist, who first suggested that DMS would be something to look for as a characteristic signature of life on a planet. Oceanic algae belch the stuff out with gusto down here – it is one of the reasons sea breezes have a distinctive smell – and volcanoes don’t.

Of course, it does not follow that the same is true on K2-18b, and DMS has also been detected on a lifeless comet, as well as created by chemical reactions in a laboratory experiment designed to replicate a planetary atmosphere. But if the science is right, there’s an awful lot of it in K2-18b’s “air”. So the burden of proof is perhaps on those who think it is not a bio-signature rather than those who think it is.

K2-18b is about eight times as large and probably somewhat hotter than earth but it does seem to be a rock, rather than a Jupiter-like ball of gas. It lies in a so called Goldilocks zone with respect to its sun, not too hot and not too cold for liquid water and therefore perhaps for life. Its atmosphere contains some carbon dioxide and methane but not carbon monoxide and ammonia, a combination which suggests it has a big ocean of liquid water but a hydrogen-rich atmosphere. Hence the astronomers are calling it a “Hycean” planet.

Given the scale of the universe, it would be more surprising if there is not life than if there is. Do the maths: so far it looks like there are planets around every fifth star; there are 200 billion stars in our own galaxy, the Milky Way; and there are about 200 billion such galaxies. If there are say five planets per solar system that would mean 200,000,000,000,000,000,000,000 (two hundred thousand billion billion) planets in all.

Even supposing just one planet in a billion is suitable for life, that’s still 200,000,000,000,000 (two hundred trillion) life-capable worlds. It would be pretty weird if ours was the only one that had life.

Many of these exoplanets will be much older than Earth, because our solar system formed when the universe was already nine billion years old. So others are bound to have had more time to spawn life and get evolution going. Life emerged here fairly soon after Earth cooled down, suggesting that if the conditions are right, it is inevitable life will emerge.

If it started billions of years earlier on other planets, then it is probable that it has had time to generate not just microbes and algae, but technology-generating beings too, and probably super-intelligent ones.

Hence the question that the physicist Enrico Fermi famously posed over lunch one day in 1950: “But where is everybody?” Aliens should be dropping by regularly in their warp-drive spaceships, or at least seeding us with microbes from time to time. And no, UFO reports don’t count as evidence: if they really were alien spacecraft we would have got decent photographs by now and certainly not kept the secret inside the notoriously leaky American government.

We can be fairly confident that they have not dropped by. We have never found a living creature on this planet that fails to use DNA or RNA, let alone our highly idiosyncratic and apparently arbitrary genetic code by which we earthlings construct protein molecules. Life here is – we now know for sure as we did not till recent decades – just one big family. Nor has fossilised evidence of a crashed spaceship turned up in any ancient rocks (except in the bad novel I started drafting once).

One worrying answer to Fermi’s question, proposed by the economist Robin Hanson in the 1990s, is that perhaps every time life reaches the point somewhere in the universe when it can start doing interstellar travel, it blows itself up. In this scenario, known as the Great Filter, billions of planets may have reached our stage of technology, including things like nuclear weapons, and none have got past it without annihilation.

An even nastier possibility, the Berserker Hypothesis, is that somewhere out there are “von Neumann probes” – spacecraft capable of replicating themselves. These effectively seek out and consume or destroy any planets before they can start colonising other worlds.

Which is why perhaps we should keep quiet and not let the aliens know we exist. Too late: our radio signals are already more than 120 light-years out – so will soon reach K2-18b. In any case, our own dimethyl sulphide biosignature has been readable by aliens for billions of years.

When it does happen that we find evidence of life elsewhere, it is almost bound to be odder than we expect, perhaps even odder than we can imagine, with a very different genetic code and very different metabolism. Will we even recognise it or figure out how it works? Its two characteristic features, I think, will be that it uses information to harness energy and create complexity, and that it experiences evolution by natural selection. But there could be some very peculiar ways to do this.

If it’s intelligent, then we face an all too mundane dilemma: who do we put up to represent us in the greeting ceremony? Donald Trump? Xi Jinping? The head of the United Nations? Please no! I reckon we should hold a grand global lottery and hand the microphone to whichever random person wins the lucky ticket.

The last word should go to Eric Idle, from the Galaxy song in the film The Meaning of Life: “So remember, when you’re feeling very small and insecure/How amazingly unlikely is your birth/And pray that there’s intelligent life somewhere up in space/’Cause there’s bugger-all down here on Earth!”

By Matt Ridley | Tagged:  science  The Mail  

Source: Matt Ridleys blog—-mattridley.co.uk