From Lisa Grossman at Science News, on an effort to update the Drake Equation:
If the civilization lasted less than 100,000 years — the time it takes light to cross the galaxy — then the odds of the signals reaching Earth while the civilization is still broadcasting are vanishingly small, the researchers report February 27 at arXiv.org. Humans, for example, have been transmitting radio waves for only about 80 years, so our radio waves cover less than 0.001 percent of the Milky Way.
“If the civilization emitted from the other side of the galaxy, when the signal arrives here, the civilization will already be gone,” says Grimaldi, of the Federal Polytechnical School of Lausanne in Switzerland.More.
The space aliens have always lived and will live in our imaginations. Maybe they came at last to prefer it that way.
See also: ET still hasn’t phoned Frank Drake
Americans don’t fear the discovery of alien life. So why do some commentators insist they do?