Rather than short, spaceship travelling creatures with big eyes and big heads, what are the prospects of humanity actually having an encounter with REAL extraterrestrials over the next generation?
The Washington Post today has an article on this scientific question.
First, the negative prospects. Here are some things, according to the Washington Post article, that should make us cautious about assuming that we will discover life beyond Earth anytime soon:
To some, debating the implications of discovering extraterrestrial life is premature at best, because — all UFO “sightings” aside — none has ever been found.
Two Viking missions to Mars in the 1970s to search for organic material did not identify any — although they were unable to dig below the rugged and parched Martian surface into the ground where scientists now think that water and possibly life could be found. In addition, the private group SETI, or Search for Extraterrestrial Intelligence, has been broadcasting radio messages to hoped-for intelligent aliens for years and listening for a response — sometimes with NASA support — but has been met so far with silence. And what some consider the rush to declare that the meteorite from Mars contained fossil remains has become an object lesson in the importance of confirming the science before making any declarations about extraterrestrial life.
On the positive side, however, are three major things. First,
[R]esearchers say . . . that they know so much more [than in the past] about extreme life-forms on Earth that could quite comfortably live on other planets. In addition to South Africa’s radioactivity-driven bacteria, extremophiles [organisms that ‘love’ extreme environments] have also been found living near super-hot sulfurous steam vents at the deep ocean floor, in pools composed almost entirely of acid, and recently two miles below the surface of the Greenland ice sheet. All get little or no energy from the sun, which sustains virtually all other life-forms, and their survival makes it more conceivable that microbes could live in the sub-surface ice or water on Mars and Europa.
Having identified more than 300 planets outside the solar system, researchers are also convinced that planets and solar systems — some probably similar to ours — are present and perhaps quite common, elsewhere in the universe. The next step is to find extrasolar planets in the “habitable zone” of their solar systems; planets whose size, makeup and distance from their sun might allow life to develop.
[T]he Hubble Space Telescope and other instruments have given researchers new data about the evolution and structure of the universe — information that makes it increasingly appear to be “fine-tuned” for life.
Lord Martin Rees, England’s Astronomer Royal made that argument as the keynote speaker at NASA’s spring astrobiology conference — saying that life could not exist on Earth or anywhere else if the basic physical dynamics of the universe were not almost precisely what they are. Slight changes in the strength of the electrical force that holds atoms together, of the pull of gravity, or of the total mass of the universe would have made it difficult for stars to form and create the heavy elements essential for life, and impossible for them to remain active long enough to support the process of evolution.
Many religious thinkers see this fine-tuning as an argument for the existence of a creator, but Rees and other cosmologists offer a different explanation: that our universe is but one in a world of multiple (or infinite) universes. However it came into being, Rees argued, our universe is inherently life-supporting, and there is no reason to believe that that potential has been realized only on Earth.
Thus, if you believe that we are not alone in the universe, and that we’ll find strong scientific evidence, over the next generation, for life beyond Earth, you’re not irrational to do so.
You’re belief has some warrant, but you still might be wrong.
Here’s the link to the full Washington Post article: http://www.washingtonpost.com/wp-dyn/content/article/2008/07/19/AR2008071901657.html?nav=rss_nation/science&sid=ST2008071902028&pos=