Weird Alien Communication: Neutrinos, Baby!

It’s All About The Neutrinos, Baby!

The first of many cool ideas for communicating with alien life is one that I read in Paul Davies’ book:  stop messing around with radio waves, and start using neutrinos.  Why neutrinos?  Well, they can pass through everything with hardly any interference.  Neutrinos are famous for hardly interacting with other matter — billions of solar neutrinos are passing right through your body right now.  So if you send a message in a neutrino beam, you don’t have to worry about your signal being blocked by some stupid gas cloud in the way.  Your signal could stream right through the gas cloud, right through the earth, indeed right through the entire galaxy, with barely any loss of signal strength.  So they’re a great practically noise-free way to communicate long distances.  Compared to the obvious choices (photons), communication in the “neutrino band” should be remarkably clean of interference or obscuration.  (Yes, it’s a word!)  In fact, several astronomers laid out the scientific case for neutrino communication in a paper by Tony Zee, prof of physics at UC Santa Barbara.

"Girl, you still as cold as a rarely-interacting neutrino. Is it because I recycled this joke from another article?"

Sounds great — what’s the problem?  Well, neutrinos are hard to catch, so receiving the message is a problem.  Their ability to pass right through other matter (an advantage for sending a message) also means they tend to drift right through your detector (a disadvantage if you want to actually read the message).  For example, the supernova SN1987A spewed out an unimaginable number of neutrinos (10⁵⁸, by one count), trillions of which were a direct hit on Earth.  We only managed to catch twenty four of them in our neutrino detectors.  In the world of neutrino astronomy, this qualified as a “neutrino burst”.  These things are hard to catch, is what I’m saying.

Zee’s paper proposes a scheme for practical neutrino communication, including such important attributes as what neutrino energies would make the signal blatantly artificial in origin (handy if you want E.T. to notice you doing it), how to encode info in a neutrino beam, and how much energy it would require.  And energy is an important point — it wouldn’t be cheap to set this thing up, so an alien civilization optimistically spraying their neutrino-message across the universe in hopes of finding us would quickly balk at the price tag.  Since they’d have to wait around for millennia for us to develop technology advanced enough to detect their signal, and would have to shoot the message everywhere (not knowing what part of the universe might be inhabited), they’d probably only send out messages intermittently, say once every 1000 years or so.  They might even wait until signs of life become unmistakably clear, and only then send a message toward the infant civilization, in which case we’ve got a while to wait — the only signs we’re emitting that indicate we exist are barely 100 light years away.  Likewise aliens might be using the neutrino band for communication among each other, but in that case they know where to aim their transmitter, and we’ll miss it unless we happen to drift into the line-of-sight path to the intended recipient.  So for that kind of detection, we’d have to be incredibly lucky.  So while this is a cool idea, there’s not much we can do about exploring it at the moment.

This raises another idea — perhaps aliens are already communicating using some weird particle we haven’t even discovered yet.  We’ve only recently hit on the idea to look in the relatively noise-free neutrino band — what other bands are waiting for us to discover, with who knows what amazing properties for interstellar communication?  Perhaps dark matter (whatever it is) turns out to be an excellent way to communicate, and once we manage to build dark matter detectors, we’ll finally be invited to the intergalactic-communication party, so to speak.  So all we need to do is 1) figure out an efficient way to catch neutrinos, or 2) solve the dark matter problem.  Somebody get on that.

And thus completes the description of the most normal of the ten ideas I’m covering here — it gets mo’ stranger from here.  Read on to learn about what crude techniques your great-great-grandfather had to use to call aliens.

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