Wavepacket Blog

Wavepacket Blog
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Sun Jul 25 22:24:41 2010
Little Green Men
SETI's poor strategy may save humankind...

SETI's first contact
Image courtesy of Wildroot (wiki)

Lately, Stephen Hawking made news with his comments that attempting to find or contact advanced civilizations are dangerous because we might tempt "nomads, looking to conquer and colonize". That is, we might attract predators (maybe even like these).

Proponents of SETI aren't worried, and continue to look for radio signals from extraterrestrials. Even our own local billionaire, Paul Allen, has jumped on to the SETI bandwagon with his own set of radio telescopes.

Some of the arguments against Hawking are valid. This article has some great points, for instance. Even a predatory advanced civilization could get whatever materials it needed without bothering with Earth.

However, I think Hawking is worth listening to. There is a chance we could meet someone friendly, but every known example of advanced contact has turned out very, very badly for the contacted civilizations. To quote Wikipedia:

The historical record indicates that when one culture is significantly more technologically advanced than the other, this side will be favored by the disruptive nature of conflict, often with dire consequences for the other society.

So on balance, why take the risk of attracting the attention of a dangerous advanced civilization?

However, there is another reason I think SETI is a waste of money and resources. As it turns out, an advanced civilization wouldn't send us electromagnetic signals anyway. Looking for radio signals is almost certainly a waste of time.

In 2004, two researchers submitted a letter to Nature. In it, they calculated the energy it would take to continuously broadcast radio (or other) signals throughout the galaxy, or even neighborhoods of the galaxy, vs. just sending physical objects to candidate systems. As they note in their abstract:

The results suggest that our initial contact with extraterrestrial civilizations may be more likely to occur through physical artefacts--essentially messages in a bottle--than via electromagnetic communication.

Their calculations were pretty back-of-the-envelope, and pretty compelling. Sending physical objects would be millions of times more efficent than beaming radio waves. Any advanced civilization would be foolish to broadcast messages.

Saturn: holding a message from aliens?
Image courtesy of TonyBallioni (wiki)

I remember when the Letter to Nature came out. Commentary noted something to the effect that we'd be better off sending probes to the Lagrange points of our gas giants than listening for radio signals. It's kind of a trippy idea: there may be ancient alien probes dormant in our solar system, waiting for us to find them!

However, even though the math is simple and the conclusion obvious (no one would try to contact us by radio waves) SETI is still looking for radio signals.

Given that Stephen Hawking thinks advanced civilizations may be dangerous, perhaps it is a good thing that SETI is barking up the wrong tree!

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