HAT CREEK, Calif. — E.T. might be phoning, but do we care enough to take the call?

Operating on money and equipment scrounged from the public and from Silicon Valley millionaires, and on the stubborn strength of their own dreams, a band of astronomers recently restarted one of the iconic quests of modern science, the search for extraterrestrial intelligence — SETI, for short — which had been interrupted last year by a lack of financing.

Early in December, a brace of 42 radio telescopes, known as the Allen Telescope Array, nestled here in the shadow of Lassen Peak, came to life and resumed hopping from star to star in the constellation Cygnus, listening for radio broadcasts from alien civilizations. The lines are now open, but with lingering financial problems, how long they will remain that way is anybody’s guess.

These should be boom times for those seeking out aliens, or at least their radio proxy.

Astronomers now know that the galaxy is teeming with at least as many planets — the presumed sites of life — as stars. Advanced life and technology might be rare in the cosmos, said Geoffrey W. Marcy, the Watson and Marilyn Alberts in the Search for Extraterrestrial Intelligence professor at the University of California, Berkeley, “but surely they are out there, because the number of Earthlike planets in the Milky Way galaxy is simply too great.”

A simple “howdy,” a squeal or squawk, or an incomprehensible stream of numbers captured by one of the antennas here at the University of California’s Hat Creek Radio Observatory would be enough to end our cosmic loneliness and change history, not to mention science. It would answer one of the most profound questions humans ask: Are we alone in the universe?