Seeking extraterrestrial intelligence

A deathly hush

The little green men may be on their way

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Readers' comments



It's possible we're alone in the universe. An amazing number of coincidences have happened in order for us to find ourselves where we are. And how much longer will we last? How long can any intelligent species on a planet last? The bacteria were first, and I don't think they will disappear any time soon. It seems the species at the top of the food chain has a propensity to becoming extinct. Maybe no intelligent species can live long enough to have contemporary contact with another intelligent alien species.

Curate's Egg

I am not really sure if we want to be in contact with alien civilization developed enough to travel space. The implications of their visit upon humanity might be catastrophic; even if these aliens are peaceful, I can definitely see a war happening amongst the major powers of the world over some piece of alien technology.

And of course, there is no guarantee that these aliens have to be peaceful. If they did not believe in... err.. human rights, and decided to make cattles out of us, we would have no way of stopping them. Claims of humanity as an irredeemably aggressive species is overblown; we are aggressive, but we don't know how high we rank on a scale of relativity because we couldn't find anyone to compare with. Answers might be surprising and extremely unpleasant.

T V Ganesh

If we haven't heard from aliens it is probably because we aren't listening the way we should. This brings us the philosophical question which asks "Does a falling tree make a sound where there are no listeners?"

T V Ganesh


"Two thousand years ago, we had a very enlightening visit from the Creator’s Son. Has he been to visit you yet?"

While we are asking that ubsurd question we should also ask if they are annually visited by a fat man in a red suit, and who their thunder god is.

Odd that in the search for intelligence on other planets we would want to demonstrate the lack of it on this one.

Wade H.

Has anybody published the amount of money being spent on this pursuit, and compared it to, say, the amount being spent on poverty reduction? I think one of the reasons the science published by scientists and any subsequent recommendations made by those same scientists is often not listeded to is that they include the wackos mentioned in this book as part of their fraternity.


That is a quite by now scientific hot point . Firstly, it would be much more probable to find artificial non biological Darwinian intelligence .Perhaps , you will find "Higher things" above your present intelligence that even can play GOD by building purely biological beings (with born and natural ageing and death-The Zeroth law of Natural Biology),otherwise not existent in natural world.Probably also the possible "contact" would mainly be "Personal-Psychological" with the Natural evolved biological social intelligent species's individual members- Stanley Kubrick -2001.It already has happened ?.However there is another point: Is there something out there, which does not came from this World and has Digestive systems? .At this point I remember the eminent Astrophysicist Fred Hoyle and its novel “The Cloud”.Remenber that remains a problem in the behavorial study of the highly intelligent "Assassin whales" why they love to eat,only in certain times, the sea -wolf babies-They have only bones and no meat all! (The Predator movie!)

blue asgard

The companion book to this one is:

How to Find a Habitable Planet (Science Essentials) by James F. Kasting

It's an excellent book, about the level of a Scientific American article with a bit of school algebra thrown in. Much to be recommended if you are attracted to Davies' book.

Kasting starts from from Frank Drake's famous equation which tries to work out how many civilisations there are to find in the Galaxy. For some of the quantities, like how many stars have planets, we have a much better estimate to-day than we had when he first drew up the equation in the 1970s. Others are still at best guesswork. One of the most critical is the length of time a civilisations lasts. The Egyptian empire lasted about 3500 years, the Romans about 1700 years. What matters is the time period in which that civilisation is likely to be detected i.e. whie we continue to use radio comparatively inefficiently. If that's about 150 years (pretty pessimistic) then there is only likely to be one civilisation in the galaxy, ours. If the time period is more like that for the longer civilisations then there may be as many as 1000 civilisations out there.

Kasting comes out with a telling anecdote about Drake, now a man in his 70s, whom he meets at a conference dinner. They are talking about sensing earth-sized planets well enough to determine if there carry life. Kasting gives him the Party line at NASA, that this will take a fleet of telescopes flying in formation to give a big enough synthetic aperture. Drake then says he knows a much cheaper way of doing it. You fly a single telescope detector in the opposite direction to the one you want to observe in, say 600 Astronomical units away, he says loftily, (1 AU is about 8 light-minutes and the solar system is about 10 light-hours across if you exclude the Oort cloud), and use the sun's gravity as a lens and image your planet that way. So Kasting tries this idea out on some of the others at the conference but they point out that the sun's corona would interfere with observations and would force you to observe from about 2200 AUs – that’s about 2 light-weeks and even if you got there you'd find the sun wobbling all over the place because of Jupiter's and Saturn's gravity (approximately 1 solar radius displacement, which would displace a 2200 AU vector by a significant portion of the radius of the solar system by the time you got out to the 10s -100s, more - of millions of AUs). This would make the enterprise significantly more expensive than the flying formation of telescopes and probably far less reliable.
Still, SETI, Drake's baby, is a fascinating enterprise and currently an entertaining one if you have the SETI at home screensaver.

I'm not at all sure we really want to hear from alien civilisations and in particular whether we want to draw attention to ourselves. Despite self-serving claims to the contrary man has evolved as a pretty aggressive species, so much so that we have specific provisions in our genes both to ensure aggression (just go down the Edgeware road on a Saturday night) and to mitigate against the consequences of losing familial genome in warfare. Its logical. Once we were hunter-gatherers (for at least 100,000 years in fact, probably much more), going around in bands of say 150 with our animals (goats, maybe sheep).We needed a lot of land to sustain a band like that and if another band tried to encroach on our territory there simply would not be enough for both to survive on. So encountering another band usually meant war, probably some deaths, and it was a life-long activity. As man became more numerous his need for land would force him out of Africa and into the rest of the World, as we've seen, with all sorts of consequences notably the invention of agriculture, civilisation and a settled way of life about 10,000 years ago. Meantime aggression and the desire for conquest or at least victory had been a survival factor and would have been selected for and this didn't go away with the beginning of civilisation, it just became more organised. Believe it or not we are far less aggressive than our ancestors, but it is still there within us expressing itself in bizarre ways. Other intelligent species will have faced just the same situation as they evolved, so if there were ever to be a meeting with aliens I very much doubt we'd be congratulating each other that we'd made it to that point. If our putative aliens had conquered their aggressive heritage they would be push-overs for those who hadn't, so probably wouldn't last long. Be careful what you wish for.

Thank you to ysksky - a brilliantly funny URL. I haven't laughed so much in years. You should post that URL to the commentary against the article labeled Paradox (a commentary on two contrary book reviews on Jesus’ life). It’ll be dynamite there.


PS - the idea that intelligence might somehow destroy itself is probably just emotional stuff from cold war days - unworthy of the Economist!


FTR the wireless ('radio' in your article) future has been widely considered, including by the UK regulator's panel on which I sit. The upshot is that wireless will get much more common, indeed the entire communications system will become wireless-fibre in form, but that random wasted 'broadcast' emissions will vanish. FTR 'the internet' is not an alternative to wireless but a system carried on it. And we have known since Shannon that idealised transmissions in any form are indistinguishable from noise in any case.

But we could now easily detect a DELIBERATELY SENT signal such as we could (and in a limited way do) transmit from most of the galaxy - so there is still a problem to explain. So one has to choose between a few options none of which look too attractive:-

- life is very rare
- life is common but multicellular life is rare
- .. but intelligent life is rare
- intelligent life is common but chooses not to be seen

The first two are tied to atmospheric Oxygen levels and should be settled by observation within a decade. The others are up for guesswork - personally I go for the last one. After all we tend to leave primitive civilizations more-or-less alone and this might be held to maximize the chances that a new civilization might come up with some intellectual breakthrough (after all about the only thing that might be tradable between the stars).

If I am right SETI is pretty pointless; even with only a few millenia of technical separation we could easily avoid observation by primitive groups if we wanted to.

But FWIW, a local alien robotic observer sounds quite possible - do not expect to find it, though!


The question "Two thousand years ago, we had a very enlightening visit from the Creator’s Son. Has he been to visit you yet?” reminds me of an Onion news article : Sumerians Look On In Confusion As God Creates World


This is an all-or-nothing kind of endeavour.

Unlike the challenge of building a rocket, where you might see different building stages, or the introduction of a new product in a foreign market where you can see it gain/lose market share, we will never know how close or how far we are from our goal or whether there is a goal at all.

Wahyd Vannoni


"Within the next 100 years, mankind may no longer use radio." Umm, there's this new invention the author may not have heard of, called a "cell phone." It uses radio, because when you're moving, you can't use a wire to connect to the internet (or anything else).


Whenever the conversation turns to the search for extra terrestrial communication by means of scanning the skies for radio waves, I always think of a small island in the Pacific where the natives sit listening for the tell-tale sound of drums. Drums are, after all, the universal method for sending messages. Yet no drum sounds can be heard from across the ocean. Meanwhile, far above their heads, plane-loads of passengers criss-cross the skies...


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