Stages of Galactic Intelligence

Imagine the history of the galaxy with respect to extraterrestrial intelligence. Very early there were only first generation stars, no heavy metals and therefore no possibility of life, much less intelligence. That's Stage One. In Stage Two planets with heavy metals form from the starstuff processed in the previous generation of stars, life arises and evolves, but It's quite some time before a technical intelligence developes. In Stage Three, radiotélescopes are invented, radio contact among...

 The Silence of the Universe is Significant

Geoff Marcy, the University of California at Berkeley astronomer who has found scores of exoplanets, and who has diligently searched for signs of anything artificial in the data, says the silence is significant: “If our Milky Way Galaxy were teeming with thousands of advanced civilizations, as depicted in science-fiction books and movies, we would already know about them. They would be sending probes to thousands of nearby stars. They would have a galactic Internet composed of laser beams a...