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AN INHABITED UNIVERSE? - cont.

We don’t yet know, but there is enticing evidence that what has happened on Earth may be the norm, and not the exception. In the past three years, astronomers have succeeded in finding planets around other stars. They have done this by measuring the subtle dance made by these stars in response to orbiting worlds. While scientists have long suspected that planets are common throughout the cosmos, they now have observational proof. And planets may be sweet oases in a hostile universe.

       We believe that it is only on these tiny, cool worlds that the complex chemistry necessary for life can exist.  It now seems probable that there are many such worlds. In August, 1996, a team of NASA and university researchers announced evidence for fossilized microbes in a meteorite that had been torn loose from the surface of Mars. This evidence suggests that billions of years ago, when the red planet was warmer and wetter, primitive life floated in its long-vanished oceans and rivers. Although controversial, this research implies that life could spring up on any half-decent planet. If it’s true that Mars once sported biology, then life is a statistic, not a miracle.
Inhabited Universe Illustration

       Supposing that planets are common and life is easily begun, then perhaps the universe contains not only myriads of living creatures, but sophisticated societies as well.  Perhaps the intelligent aliens that routinely appear in films and television have real counterparts in our galaxy.

       How could we find such extraterrestrial beings? Rocketing off to other star systems is not feasible: Even with our fastest spacecraft, it would take more than 50,000 years to reach the nearest of these.

       But nearly four decades ago, it was realized that while interstellar travel was expensive and time-consuming, interstellar communication might not be. Radio waves, particularly those at microwave frequencies, could easily penetrate the gas and dust between the stars. And even a modest signal, if properly beamed, would be sufficient to send a message from one star to another. Such signals would travel at the speed of light.

       Scientists don’t broadcast deliberate signals into space, hoping to stir the interest of nearby aliens. But what some astronomers have done for many years is to listen. They use large antennas (radio telescopes) connected to sophisticated digital receivers in the hope of eavesdropping on radio traffic that may already suffuse the star fields of our galaxy. This enterprise is known as SETI, the Search for Extraterrestrial Intelligence.

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