[LINK] "Talking to the neighbours"

[rfmcdonald]

The Economist reported on a proposal for an interstellar communications network. Instead of using electromagnetic radiation as has frequently been proposed, coherent beams of neutrinos--ultra-light particles which travel very close to the speed of light and rarely interact with matter--might be it.

[T]echniques that work well on Earth are not necessarily ideal for talking across the vast chasms that separate stars. And for several years John Learned of the University of Hawaii and Anthony Zee of the University of California, Santa Barbara, have been promulgating what they believe is a better idea. They suggest that any alien civilisation worth its salt would alight not on the photons of the electromagnetic spectrum—whether optical or radio-frequency—to send messages to other solar systems. Rather, it would focus its attention on a different fundamental particle, one that is rather neglected by human technologists. That particle is the neutrino.

Neutrinos, it must be confessed, are neglected for a reason. Though abundant (the universe probably contains more of them than any other sort of particle except photons), they are fiendishly difficult to detect. That is because they interact only occasionally with other forms of matter. But that is precisely why Dr Learned and Dr Zee like the look of them. Light and radio waves are absorbed and scattered by interstellar gas and dust. Neutrinos would pass straight through such obstacles, and could easily be detected by neutrino telescopes on Earth (which typically consist of giant vats of water or, more recently, huge chunks of Antarctic ice).

[. . .]

To detect artificial neutrinos using existing telescopes means screening out the natural neutrino background. Fortunately, much of that is produced by nuclear reactions in stars, and such stellar neutrinos have relatively low energies. If the aliens made their beams out of neutrinos that were a billion times more energetic than the ones emanating from stars (something the researchers argue is not completely beyond the bounds of current technological imagination), the background noise would disappear. At high enough energies the rest of the galaxy is so quiet that if someone detected even a couple of energetic neutrinos arriving from the same direction, it would almost certainly mean they were artificial.

Go, read.