Perhaps there's nobody out there after all. Or perhaps it's just early days in the search for extraterrestrial intelligence (SETI), and we're listening to the wrong star systems or at the wrong wavelengths.
There is another possibility, says Douglas Vakoch, head of the Interstellar Message Composition programme at the SETI Institute in Mountain View, California, which ponders the question of how we should communicate with aliens. "Maybe everyone's listening but no one is transmitting. Maybe it takes an audacious young civilisation like ours to do that."
So should we start sending messages into the void? And if so, how can we make ourselves understood to beings we know nothing about?
One astronomer has already stepped up to the challenge. Alexander Zaitsev at the Russian Academy of Science's Institute of Radio Engineering and Electronics in Moscow has sent four interstellar messages since 1999, each beamed to no more than a handful of nearby sun-like stars. Zaitsev's efforts are pretty small scale, however, and so far his group is more or less alone except for some low-power operations offering to send your message to the stars for a fee.That could be about to change. Perhaps bored with spending so long hearing nothing, the wider SETI community is starting to consider a more active approach. They will get together to discuss whether to go for it at a meeting in April in League City, Texas. Vakoch, who will chair these sessions, is all in favour. "I have long held the position that after broad-based international consultation, we should be doing active SETI," he says.
It's an approach that worries ex-astronomer and science fiction author David Brin, who was a member of the International Academy of Astronautics SETI panel until 2006. He resigned when the committee backtracked on the wording of a protocol that called for discussion before deliberately broadcasting into space. "I dislike seeing my children's destiny being gambled with by a couple of dozen arrogant people who cling to one image of the alien," says Brin. Since then three other members have quit for similar reasons. Vakoch has some sympathy with Brin's point of view. "These issues are much too important and too complex to be resolved after only a few days of discussion."
If the enthusiasts for active SETI get their way and there is a real effort to send a message, the next question is: what should we say?
Some early attempts to communicate with aliens - including the plaques attached to NASA's Pioneer 10 and 11 spacecraft, and the phonograph records on the Voyager probes - were really only symbolic efforts. More likely to be received one day is the powerful radio broadcast devised by SETI pioneer Frank Drake and sent from the Arecibo telescope in Puerto Rico in 1974. We have a long wait for contact if we rely on this, though: the message won't reach the distant star cluster it was aimed at, M13, for 25,000 years. It was also a very brief message, containing only 210 bytes of information.
"These are greeting cards," says Seth Shostak, who is a senior astronomer at the SETI Institute. "It is nice to get a greeting card, but hard to decipher if it's in a language you don't understand, because the amount of material is so limited."
Interstellar geek speak
Although the Arecibo message is cunningly constructed, it is difficult even for a human to understand. The signal contains a series of 1679 bits, a number chosen as it is equal to the product of two prime numbers - 23 and 73. The hope is this will prompt an acute alien recipient to arrange the 1s and 0s into a 23-by-73 rectangle. Doing so reveals a rather complicated picture, which is supposed to give some basic information about our chemical and biological make-up, our civilisation and the solar system (see illustration).
To me it looks a bit like a small person with a big head, four eyes and eight bushy eyebrows. So the only bit I've got right is the "person", and there I had a big advantage. "It is much worse if you don't have lot of context, if you don't even know about Homo sapiens," says Shostak.
So where might we find some common ground with ET? Perhaps in mathematics. This idea goes back about three centuries, when it was suggested that we could hail beings on the moon by cutting a diagram of Pythagoras's theorem into the forests of Siberia.
read full article http://www.newscientist.com/article/mg20527441.300-exolanguage-do-you-speak-alien.html
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