Loud and Clear Department: Intergalactic Telegrams

After 26 years of listening for radio transmissions from deep space, we learn this week that aliens - at least the really smart ones - could have been trying to contact us by a totally different method: manipulating the brightness of stars using stupendously powerful blasts of neutrinos. Or so say University of Hawaii physicist John Learned and his colleagues in a recent article on the physics forum arXiv. It's simple, writes Learned: aim your neutrino beam at a pulsating Cepheid star, and with enough energy input you can change the frequency of the pulsations - a kind of binary signal that any old sentient being equipped with eyes and a modicum of curiosity could pick up on. I mean (and you can almost hear the exasperation in his words), even humans have been watching Cepheids since the late sixteenth century. Learned calls the technique "star tickling" and suggests that star-tickling aliens could even now be waiting for us to clue in and start deciphering the oscillations. He suggests that data could be transferred over immense distances this way, giving us a sort of "galactic internet." You've got to give him credit for thinking big. Still, you wouldn't want to swap too many vacation photos on this system. With data rates of roughly 180 bits per year, according to Nature News, that 100 kB picture of you eating a fried twinkie at the fair would take a bit more than 4,500 years to download. So it's really more of a galactic telegram system. Also, you could run into trouble on your power bill. Each neutrino blast needs to contain roughly 1 millionth of the star's energy before the Cepheid starts feeling ticklish. But I like this expansive thinking. Whenever I get to talk with physicists, I always come away thinking how marvelous it must be to spend so much of your life being mostly correct and nearly insane all at the same time. And if you're going to spend your time thinking of ways that aliens could be calling to us, you might as well cover all the possibilities. Best of all, Learned keeps his suggestions practical, stopping well short of the ludicrous:

"In another context, the use of the cosmic microwave background to reach everyone in the universe was also considered [5] but as far as we know that is not within the capability of any inhabitants of the universe."​

At least with Cepheid stars, we have 100 years of observations to fall back on. A graduate student given a laptop and enough Code Red could have the answer in a few months. (Although, their optimism notwithstanding, it does appear that Learned and colleagues opted to publish their paper before running that analysis.)