The existence of a race of sentient alien robots might be not just possible, but inevitable. In fact, we might be living in a "postbiological universe" right now, in which intelligent extraterrestrials somewhere have exchanged organic brains for artificial ones.

The driving factor is a pragmatic desire to improve mental capacity. Alien beings may have already reached a point in their evolution where, having exhausted the potential of their biological brains, they have taken the next logical step and opted for robotic brains equipped with artificial intelligence.

For as long as humans have looked to the night sky to divine meaning and a place in the universe, we have let our minds wander to thoughts of distant worlds populated by beings unlike ourselves. The ancient Greeks were the first Western thinkers to consider formally the possibility of an infinite universe housing an infinite number of civilizations.

Just because NASA has two robots on the surface right now doesn't mean the landing of the Phoenix probe is a sure thing. At a news conference yesterday, NASA officials stressed that landing a spacecraft on Mars isn't easy: 55 percent of all attempts to do so have failed. Not to mention that the technique Phoenix will use to do so hasn't been employed in a while.

At 4 PM on April 19, 1984, a team of air traffic controllers at an airport in the east of England reportedly watched a strange, bright, circular vehicle touch down, then blast off again at a tremendous speed and with a near vertical trajectory. Although they didn't want their names to be included in the report covering the event, they believed it was a UFO. And they were sober.

Radivoje Lajic thinks aliens don't like him. The Bosnian man says his home has been hit by meteorites no less than five times. He took the rocks to experts at Belgrade University, who confirmed that they are the real thing. But they haven't been able to verify that Lajic did anything to anger the extraterrestrials, or that he's the target of some extra-planetary prank. Still, Lajic seems sure this isn't just a coincidence.

Everyone seems to be double-extra-cautiously optimistic about this finding, so dont go running out to your telescope tonight looking for greetings from friendly space creatures.

But in work reported today in Nature, astronomers say they used the Hubble Space Telescopes infrared imager to pick up signs of methane in the atmosphere of a Jupiter-sized planet orbiting a star some 63 million light years from Earth. And methane, an organic molecule, is an indicator of the possible presence of life.

For a closer look at the exotic aircraft the Air Force might be cooking up at Area 51, launch the photo gallery.

As bizarre as it may seem, the sample jars brimming with cloudy, reddish rainwater in Godfrey Louis´s laboratory in southern India may hold, well, aliens. In April, Louis, a solid-state physicist at Mahatma Gandhi University, published a paper
in the prestigious peer-reviewed journal Astrophysics and Space Science in which he hypothesizes that the samples-water taken from the mysterious blood-colored showers that fell sporadically across Louis´s home state of Kerala in the summer of 2001-contain microbes from outer space.