The search for extraterrestrial intelligence assumes that ET will be communicating using photons. But despite decades of listening out, we’ve heard nothing.
But today, John Learned from the University of Hawaii and pals say forget photons. We should be looking for evidence of ET using neutrinos.
The reason is that any civilisation advanced enough to colonise the galaxy would need a reliable way to communicate over intragalactic distances and photons simply don’t pass muster. There is a huge amount of noise in the electromagnetic spectrum, photons are easily scattered and would almost certainly be absorbed if they had to travel from one side of the galaxy to the other.
By contrast, the neutrino spectrum is relatively noise free and neutrinos intereact so weakly with matter that a signal could travel unhindered from one side of the galaxy to the other.
They propose testing the idea by generating a neutrino signal using a particle acclerator to genreate Z nought particles which decay into neutrinos of a relatively easily detectable energy. They would encode information in the time structure of the beam, like Morse code.
What’s more, Learned and co say that the kind of neutrino signals that ET might be expected to beam should be detectable by the generation of neutrino detectors now under construction.
Ref: arxiv.org/abs/0805.2429: Galactic Neutrino Communication