Guest Editorial

Is the risk of interstellar transmissions from Earth justifiable? Several distinguished physicists think not. Stephen Hawking has warned that we could face a Columbus-coming-to-America scenario, with Earth playing the role of the Native Americans. Michio Kaku has pointed out that Cortes conquered the entire Aztec empire in less than two years, with technology that was only perhaps 1,000 years more advanced. If aliens showed up here, the technological disparity might well be tens of times greater in magnitude.

I for one believe this argument is flawed, for the following reasons:

1. The Incas and Aztecs did little to oppose the Spanish invasion because they believed that the Conquistadors were godlike people. Had they resisted, the Spanish would likely not have succeed. The Spanish had guns, but the Inca and Aztec peoples had the huge number of soldiers.
2. In some cases, the Spanish used local mercenaries to wage war.
3. A lot of Spanish died because of sickness.
4. The Conquistadors came to America of their own accord. They were explorers. They were not invited by a smoke-signal message sent out by the Incas. So, the parallel with Messaging to ExtraTerrestrial Intelligence (METI) is not valid.

Furthermore, there are examples in history were a more advanced civilisation fell before a more primitive one (ie. the defeat of Rome by the Goths).

From a point of view of physics, it is extremely difficult to journey between stars. The energy requirement is enormous. Those familiar with the Daedalus project will recall that the starship's initial mass is 150,000 tons to send a 500 ton probe to the Barnard Star, and the trip would take 40 years. I'm not too concerned about interstellar empires. Conquering other worlds is a huge expense of resources. A civilisation trying to be stable for centuries cannot afford this kind of luxury.

I think Kaku and Hawking can rest easy. Even if we transmit, the extraterrestrials are not coming here to conquer us.

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