Thursday, October 07, 2004

Update on the SETI signal

I watched part of contact this weekend, so I was wondering what happened to this news story.

The signal, named SHGbo2+14a, apparently emanating from a point between the constellations Pisces and Aries, had been picked up twice by an ingenious SETI scheme which harnesses screensaver programs on millions of personal computers to sift through cosmic noise picked up by a giant radio telescope in Puerto Rico.

Alas: There's nothing there to show SHGbo2+14a is ET's calling card.

Indeed, it is only one of a batch of low-grade "candidate" signals that have been sifted from trillions -- and, given the risk that it could be a statistical freak or the result of equipment interference, it has so far not even been upgraded to the category of "promising," says SETI's Seth Shostak.

Then the article tries to discredit SETI.

No, according to rival theories aired last week in the British weekly science journal Nature, which suggest we have been looking for evidence in the wrong place.

To send a long message on a radio beam, repeatedly over a very long time and across a wide galactic scale, in the hope that someone eventually receives it, is a hugely inefficient use of energy.

It would be more energy-efficient to send out space probes or inscribed artefacts, "effectively messages in a bottle," suggests Woodruff Sullivan, an astronomer at the University of Washington in Washington state.

Now I take offense to this, they actually insulted my intelligence.

"To send a long message on a radio beam, repeatedly over a very long time...Is a hugely inefficient use of energy."

I would agree with this if the aliens trying to contact us where not an advanced race, followed the human rules of economics, and had a short lifespan. When an article start talking about what an alien would judge as efficient and inefficient, I start to discount it.

The message in the bottle analogy does not hold water with me. Space is mostly space, but if you ever actually get close to anything, you will most likely just crash into it. The land to water ratio is vastly larger than the stuff to space ratio. In other words you chances of getting a message across an ocean are much higher than getting space probe next to an actual space object. A low percentage of "space probes" would actually remain viable, due to the lack of anything there. If a message in a bottle gets close to anything, it is probably what you want (an inhabited land mass). If a space probe gets close to an actual object, it is most likely not what you want and the space probe will most likely crash into it.

Radio waves have none of those limitations. They cover large areas at once. They cover the vastness of space as well as can be hoped (the speed of light). The only limitation is that they grow weaker and less defined the longer they travel. Which is where the energy-efficient argument comes in. The more power you pump into the longer they last. That argument assumes that energy efficiency is something aliens care about. Though I guess searching for radio waves assumes that aliens don't care about energy efficiency. If you were going to get contact from aliens, which ones would you go looking for: the really advanced ones using radio waves or the ones sending space probes out for fun.

Radio waves may not be a good means of communicating through space, but they are an excellent means of first contact. After first contact is made, I don't know what is a good way of talking to aliens, but then again the only person who knows that is the crazy person down the street.


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