“Most of my colleagues don’t really care much about what the aliens might look like so long as they can build that transmitter”
binary all you have to do is decide ‘is the signal there, or is it not there?’. If you try some other sort of encoding, such as analogue with many different gradations, then you either have to detect many different levels of signal for traditional AM radio or, for signals such as FM or spread-spectrum, you need some kind of knowledge of the parameters used for the signal encoding.
There are many different ways of sending information, but binary just happens to be the simplest. You can see that in the development of radio. Morse code was the first way of sending information – essentially just turning the transmitter on and off in a pattern. That’s the easiest thing to do and it’s also fairly noise tolerant – any signalling channel will always have noise, and so having a system that doesn’t get affected so much by the signal-to-noise ratio has advantages.
I don’t think binary is any more anthropocentric than saying you might send pictures in a ‘raster grid’ of pixels. Some people might argue that’s what humans do, but aliens might send pictures by vector descriptions [describing lines by their direction and length]. And maybe that’s what they would do among themselves, but if they’re trying to communicate with someone else who they don’t know anything about, I think they’d probably go for something straightforward.
I guess that brings us to a related question – what can we guess about how other intelligences might think, and how would that affect our attempts to communicate with them?
Well in terms of intelligence, SETI scientists tend to have an operational definition – if you can build a transmitter, you’re intelligent. Most of my colleagues here don’t really care much about what the aliens might look like so long as they can build that transmitter. I think that’s maybe a little simple, because if you look at what we’re currently doing in this century with machine intelligence, in some ways we’re developing our successors.
Those machines don’t have to wait a third of a million years to maybe get a bit more intelligent – they’re not stuck with Darwin and can design their own successors, so very quickly we’re going to get intelligence that just dwarfs the collective intelligence of all humanity. So very quickly we’re going to have these really, really smart machines. I don’t know what they’ll do – they might just sit around playing FreeCell all day – some of them might leave. I don’t think that’s an unreasonable assumption – Earthlike planets aren’t really places with a high concentration of energy. We get some sunlight, we have fossil fuels and all that, but if you really want energy then you might go to the centre of the galaxy – there’s a giant black hole there, and you can harvest a lot of energy out of that. Maybe not all of these machine intelligences will get up and leave, but if just one or two per cent do that, then the consequences could still be that the majority of intelligence in the galaxy would be synthetic.
If that’s right, then it throws a real monkey wrench into the SETI enterprise, because you no longer know where to point your antennae or look for laser flashes. They might not be coming from stellar systems with the potential for habitable planets as we’ve always assumed – they could be coming from machines in interstellar space, or maybe the machines simply wouldn’t make their positions known. It could be that looking for analogues of ourselves, while it’s appealing and certainly the basis for a lot of movies, is maybe like trilobites looking for other trilobites!
So far, if we think of human messages sent to the stars, they’ve mostly involved pictures. Do you think that’s the best way of doing it? And are there any alternatives in terms of finding a ‘language’ to communicate with aliens?
Well, pictorial communication does assume that the aliens have eyes, but eyes are pretty useful if you’re on a planet around a star. All that radiation can give you a lot of information about where to find dinner or a mate or anything else, and even single-celled organisms in the ocean often have some sort of light-sensitivity – it’s something that’s evolved several times so it seems like a good idea. Communicating with music is something that’s shown a lot in movies [he imitates the Close Encounters theme], but that’s pretty slow and ambiguous if you ask me.
If you say not pictures, then what about mathematics? There’s a guy in Holland, Hans Freudenthal, who has developed a whole language based on mathematics called Lincos, short for ‘Lingua Cosmica’. He figures if the aliens can build a radio transmitter or laser they’ll know mathematics, and math is presumably universal, so they’ll understand the relationships in the language. But again, you can convey certain things like inequalities, logic and the Pythagorean theorem, but I don’t think it’s a great way to communicate – you can't explain everything with mathematics.
So while they’re very admirable in their way, I don’t think these efforts are really necessary. Think
about how we decoded messages in unknown languages. The canonical example is Egyptian hieroglyphics. In that case we had the Rosetta Stone to make it easier, but if we hadn’t found that, they still would have been deciphered – partly because the hieroglyphs were written by other humans, but mostly because there are a lot of them out there. If you look at any inscription or go into any tomb in the Valley of the Kings, or any sarcophagus, there are hieroglyphs everywhere. That’s a lot of material, and if you have a lot of material, you can start to look for redundancies, things that repeat and other common features – similar to the way the Enigma codes were cracked during World War II.
So if we did make a concerted effort to contact an alien civilisation, what format do you think the message should take?
Well the famous Arecibo message was really just a demonstration, and while there have been other messages sent since, they’ve all been rather similar – they’re fairly short, lasting for minutes rather than years, and they have to be very easy to decode and don’t contain a lot of info.
My suggestion is to send the contents of the Google servers that are located just down the street from us in Mountain View. If we sent the entire Internet, encoded into a simple pictorial form, then it’s like the hieroglyphs – there’s a lot of material. If the aliens picked up a week’s worth of data, they might see the little symbols ‘d-o-g’ – they don’t know English, they don’t know the alphabet, but often where they see the symbols they find there’s also a picture of this furry animal with four legs and a tail. If they scan through and look for things that recur, then in that very simple way you could learn a whole bunch of nouns.
I’d go for that simple approach rather than trying to do things with music, mathematics or something else. The other approaches are predicated on the idea that the message will be short, but if the aliens are hundreds of even thousands of light years away, it’s going to take so long to send and receive signals anyway, you might as well send a lot of stuff!
Finally, I wonder if you have any thoughts about the sceptics who wonder whether the idea of attempting to communicate is really a good idea. And assuming we do, who do you think should be in charge of that communication?
It’s actually become something of a hot topic, perhaps because Stephen Hawking commented on the dangers. A science-fiction author I know, David Brin, gets very passionate about this subject because he thinks that we may be threatening the future of humanity. Of course that might be true – we don’t know what’s out there and it’s possible that some fraction of the societies that are out there are aggressive. If they pick up signals that we’re here and send their interstellar battlewagons and that's the end of civilisation on Earth, then that’s not going to look good on your resumé.
David thinks the SETI community should come out against this, but the SETI community isn’t really the problem. We don’t have any transmitters and aren’t really doing much of this stuff. And are you going to ban transmissions to the sky? The fact is that Heathrow’s trying to get in touch every hour of every day thanks to radar. Evidence of our existence here has been going out since the war with the invention of radar – low-frequency AM radio doesn’t get through Earth’s ionosphere very well, but radar beams are broadcasting into space – and what are you going to do? Are we saying that from now until forever we can’t develop any highfrequency transmitters? It’s a bit like saying we can’t ever build a clever computer because it might be dangerous. The time for worrying about it is long past, and I don’t see how it would be a good idea to somehow interdict technological development.
As for the question of who gets to decide what we send – well of course I think I should!