ETs could use stars to signal us

University of Hawaii physicists suggest that extraterrestrials might send messages by tweaking the brightness of certain stars. Cepheid stars brighten and dim on a regular cycle. John Learned and his colleagues posit that an ET civilization might change the timing of that cycle by firing a high-energy neutrino beam, for example, into the star. From Nature:

The normal and shortened pulses could be used to encode data, to form what the researchers call a 'galactic Internet' in a paper…

Learned admits that the galactic internet would be slow – a Cepheid with a roughly one-day period could transmit about 180 bits per year. Such a transmission would require roughly a millionth of the star's energy, the researchers estimate…

Learned says that finding a signal from the galactic internet is a long shot – but, he says, we've got 100 years of data on Cepheids in which to look.

"Analyzing that data would take a graduate student a couple of months, and just think if it turned out to be correct," says Learned. "The implications would be astounding."

"'Galactic Internet' proposed" (Nature)