WE APPEAR TO BE ALONE

There are approximately 100,000,000,000,000,000,000,000 stars in the Universe. And probably more planets than stars. Yet in all this immensity there is only place we know of where life exists: Earth. Despite searches for intelligent signals, no sign of intelligent extraterrestrial life has been found. In fact, there is a good argument that if such life-forms exist out there, not only should we see signs of them but they should already have come here. One physicist Enrico Fermi asks "Where Are They"? Some astronomers think the answer is we are alone, that someone has to be the first. But absence of evidence is not evidence of absence. It took three billion years for us to go from single cells to complex life, which suggests evolution of living matter is an extremely complex process. Technological civilizations like ours may be rare and their lifetimes short; we may have missed any others by millions or billions of years. The other alternative is that the nearest civilization may simply be too far away for us to detect.