Computer-processing power has roughly doubled every two years for the past 50. Astromner Frank Drake from West Virginia and other SETI scientists believe that within 30 years or so, computing advances will allow them to sift through enough frequencies from enough of the 200 billion stars in our galaxy to have a reasonable shot at finding a signal from an extraterrestrial civilization. “My guess—and ‘guess’ is the right word—is that the number of detectable civilizations in our galaxy right now is 10,000,” Drake says. “That means one of every some millions of stars has a detectable civilization.” His estimate, he adds, assumes an average life span of about 10,000 years for a technological civilization. “In 20 or 30 years we will be able to look at 10 million stars. That’s the challenge, even though it’s based on a guess.”
Drake may be too conservative, says Seth Shostak, senior astronomer at the SETI Institute. “If this experiment has merit, it’s going to succeed within two or three decades,” he says. “If it doesn’t, then there’s something fundamentally wrong in our assumptions. If it’s going to happen, it’s going to happen soon.”
Drake and Shostak could, of course, be wildly off base. It is not hard to find astronomers who would peg the number of civilizations in our galaxy at one—our own. But if Drake and Shostak are right—if we are within a few decades of discovering that we are not alone in the universe—what then? What happens after we detect a signal from an alien intelligence? Could we even translate the message? How likely is it that the message might contain knowledge that would transform our culture? Would it be dangerous to respond and reveal our existence to beings from other worlds?
One thing that definitely won’t happen if SETI scientists discover such a signal is a government cover-up or any sort of conspiratorial secrecy. The world will learn the news almost immediately. Shostak is certain of this. So is Jill Tarter, director of the SETI Institute’s research center. They know exactly how events will unfold when they finally find a signal because on a June morning 13 years ago, they thought they had received one.