SEARCHING FOR THE (Y)SETI

S.E.T.I: The Search for Extra-Terrestrial Intelligence. All around the world, the biggest radio telescopes we have are spending much of their time in an internationally funded drive to discover intelligent life beyond our planet. Ask any of the astronomers involved and they’ll tell you why it’s so important. They want to answer the question ‘are we unique?’ Is mankind special to the point that we are the only technological capable beings around? This search, of course, is another of those science-versus-spirit things and it could be the biggest boondoggle since the London Dome. (Boondoggle: American slang for a useless and expensive project designed to divert public funds into personal pockets). What they are doing is listening for very faint radio signals that are unmistakeably generated by an alien technology, and, at the same time they are beaming signals into deep space to let others know we are here.

While all this is going on, we are searching for signs of primitive life on other planets and moons in the solar system. Several Mars probes have gone the tens of millions of miles to soft-land on Mars and test rocks for traces of bacteria.

So why is S.E.T.I. a ‘boondoggle’? It’s a boondoggle for two reasons: First; the question about other life and other civilisations can be answered by sitting in your armchair and doing some simple sums with some very, very big numbers in them. Second; Even if such a civilisation does exist, there is no way they’ll ever spot us. Not, at least, until we’re long gone from the planet.

The universe is big, mind-bogglingly big. So big, in fact that we’ve had to come up with a way of describing and measuring the distances involved. What we use is a unit of distance called a ‘light year’. It’s not a measurement of time, although it has big implications relating to time, it’s a very big version of a metre or a yard. We know that, in this universe, at least, light travels at a constant speed; 186,000 miles PER SECOND. We also know that that’s as fast as anything can go. So you can relate that to Michael Schumacher’s Ferrari, that’s six thousand six hundred and ninety six point six million miles per hour. It’s very, very fast. A particle of light is called a photon. Photons always zoom about at that speed. When a photon leaves the sun, it takes about ten minutes to get to earth. That’s covering about 93million miles in ten minutes. We can call that distance (93million miles) ‘ten light-minutes’. A light-year is how far that photon can go in one year, and that’s actually 5,865,696,000,000 miles, and that’s a very silly number (it’s a lot easier, and it takes up less space on the page, to call that distance One Light-Year).

So a light-year is a shorthand way of calibrating very big distances. Our speed crazy little photon is not only the fastest thing around, it’s also a bit of a time-machine as well. Actually it’s not so much a ‘time machine’ as a ‘time-o-scope’. It let’s you look back in time. Unfortunately it only works for looking back, so you can’t use it for winning the lottery next week. Let’s go back to the fact that it takes this photon (small bit of light) ten minutes to get from the surface of the sun to the back of your eyeball. That means that you are seeing the sun now as it was ten minutes ago. If you were an alien on a planet sixty five light years away and you had a super long distance radio, you could hear Winston Churchill deliver his ‘finest hour’ speech LIVE as it happened. So when we see a star which is ten light-years away, we are seeing it as it was ten years ago. We can’t know if it’s actually there right now, in fact it could have just this minute blown up, but we’ll have to wait ten years to see the bang!

So what does this have to do with boondoggles? We send out a signal, a radio signal that is made of photons. Off they go at 186,000 miles per second. In a hundred years they will have travelled a hundred light-years, and that’s not far by cosmic standards. In fact they’ve probably not quite made it as far as the corner shop in our cosmic neighbourhood. There aren’t many stars (with planets) that close. The odds of one of that handful of planets having a population that can pick up our greeting are nil, zero, none what-so-ever. Let’s assume, by some miracle, that there is a planet (planet ‘Zog’) one hundred light-years away which has its radio tuned in to planet Earth. The Zogians could pick up one of our earliest radio broadcasts, maybe. If their radio is not quite so sensitive they’ll have to wait a hundred years until one of the signals we’re sending NOW will get there. They are also into boondoggles, so they’re listening for it. Aha! “There is life out there”, they say, “Let’s reply so we can say hello.” Of course they want to use the fastest means possible, because they can’t wait to see if their ‘X Factor’ is better than ours. So they send off the fastest thing they’ve got; our speedy little friend, the photon. One hundred years later the photon arrives and we get the reply. That’s two hundred years to say ‘Hello’. It could take an awfully long time to check out ‘X Factor’ on planet Zog.

We’ll come back to this very pedestrian inter-stellar conversation later.

Let’s go back to whether or not there is intelligent life out there. (Even it’s so far away that we can’t communicate with it very well.) It’s time to look at some more mega-numbers:

The Earth orbits the sun, which is a bog-standard average type star. Out of about ten planets orbiting our star, only one has a technological society. We can tell from looking around our bit of our galaxy (that’s a bunch of stars hanging out together), that most stars don’t have planets, but quite a few do. Let’s say, for the sake of argument, that only one in ten stars has any planets. Let’s also say that watery earth-type planets that are just the right distance from their star to neither freeze nor boil are pretty rare, say one star in a million that do have planets, has got a planet that could support life as we know it. That means the odds of such a planet orbiting a star are one in ten million. That certainly looks like very long odds. Especially if we also reckon that, even with the right kind of planet, only one in another million actually has managed to produce technology. So now the odds are one in TEN MILLION MILLION, that’s ten thousand billion.

There are, at present best estimates, one hundred billion stars in our galaxy. So from those odds, we probably are the only planet in our galaxy with technology based on life as we know it. By our odds, we’d have to search one hundred galaxies to find our target. How many Galaxies are there out there? At best estimates there are two hundred billion that we could possibly see and many more that are so far away we’ll never see them. So if we searched two hundred billion galaxies we should find (by our crude odds) two billion earth-type planets with technological societies. Two billion!

Is there intelligent life out there? Of course there is. Save your money and use your telescopes for something more useful. We’ve figured it out without so much as a PhD in astrophysics!

Now let’s say there is a civilisation in a galaxy not too far away. The nearest galaxy is 250 thousand light years away. It’s a tiny little thing called Canis Major (big dog) and it’s what’s known as a dwarf galaxy. It’s not so much a big dog as a small rodent in galactic terms. So we’ll probably have to look a bit further than that. If we get lucky we might strike it rich in a galaxy quite close to use, say, ten million light years away. If we remember our conversation with the Zogians that was taking two hundred years (just to shake hands and say ‘hello’), we are now looking at twenty million years to do just that. In other words, it’s not worth the effort. We know they’re out there and we know we can’t ever talk to them or ever meet up.

The Search for Extra-Terrestrial Intelligence? Boondoggle!