After the discovery of the fossil of a microorganism in the Meteorite, ALH84001 that -the scientists believe- came from Mars, they say one thing for sure that the possibility of finding microbial life in others planets outsides the Solar system is not totally impossible (NASA). Moreover, current discoveries of several extremophiles or microbes -for an instance, microbes like Pyrolobus fumarii have been found to survive in a temperature of 113°C and microorganisms like Methanococcus jannaschii (Encyclopedia of Science) cannot tolerate Oxygen while living near hydrothermal vents 2,600 meters below sea level, under the crushing pressure of the seawater- in apparently hostile conditions enhanced the likelihood of finding microbial life in any corner of this universe (Mullen). But yet they can not assert that life in more complex forms or intelligent life can be found elsewhere in this universe on these singular discoveries because the discouraging theories of life of Earth also cannot be totally blown out. Indeed there are many theories about life on other worlds, but the scholarly consensus is usually that, although it probably exists, our chances of meeting it are slim.
Such uncertainty of finding a life of the earth arises for two points. First, since the fossil of the microbe in the ALH84001 meteorite shows that those microbes, 3.6 billion years ago (NASA), had been the victim of extinction, environmental congeniality, no matter how tough the extremophiles are, necessarily must be tenable enough to -as Dawkins’ Weasel Program shows- preserve the complex organic changes in one stage of the evolution to reach its next. Given that the environment is endlessly hostile, the possibility of any extremophiles is the lowest that tends closely towards zero (Ward 49-50). Even if life continues to survive in any endlessly hostile environment, that life can be defined as life as it is perceived onearth. Second, the discovery of a new domain of microbial life called, Archaea, has provoked the biologists to speculate whether there exists any non-carbonic form of life.