In the infinity of space, it would be very naive to assume we are the only form of life that exists, has ever existed, or may exist in the future. Several scientists from NASA and Stanford University announced their findings of ancient, fossilized, microscopic life from a Martian meteorite, known as ALH84001. The meteorite was catapulted away from Mars fifteen million years ago when a huge comet or asteroid impacted the surface. The meteorite travelled through space for millions of years and then encountered the Earth. It entered Earth's atmosphere about thirteen thousand years ago and landed at Antarctica. The meteorite lay there until 1984, when a team from the NASA Johnson Space Center found it while exploring the Allan Hills ice field, and brought it back to Houston. It was initially classified as a lunar meteorite, but in 1993 was correctly identified as from Mars. It is one of only twelve "SNC" meteorites, which match the unique chemical signature of Mars. So when you consider the existence of us, and evidence of other life BOTH sharing a relatively minature pocket of space, to write off the idea of extraterrestrial life would be IMO rather narrow minded. The fact we have not established commuication from outer space is down to the sheer lack of speed & distance of our radio signals, which SETI transmit 24 hours a day 7 days a week, hoping for a reply, when in reality we have covered an area the size of a pea in the Atlantic ocean. Still, even today The first signal pulse transmitted in the 70's has only reached a relatively short distance. For a signal to reach ET life and be replied to, just doubles the waiting time. Whether space in in fact infinate or not, is the ultimate question which will probably never be answered.