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The Fermi paradox is a paradox proposed by physicist Enrico Fermi that questions the possibilities of finding intelligent extraterrestrial life. More specifically, it deals with the attempts to answer one of the most profound questions of all time: "Are we (the earthlings) the only technologically advanced civilization in the Universe?". The Drake equation for estimating the number of extraterrestrial civilizations with which we might come in contact seems to imply that we should not expect such contact to be extremely rare. Fermi's response to this conclusion was that if there were very many advanced extraterrestrial civilizations in our galaxy, then, "Where are they? Why haven't we seen any traces of intelligent extraterrestrial life e.g. probes, spacecraft or transmissions?". Those that adhere to the premise behind the Fermi paradox often refer to that premise as the Fermi principle.
The paradox can be summed up as follows: The commonly held belief that the universe has many technologically advanced civilizations combined with our observations that suggest otherwise, is paradoxical, suggesting that either our understanding or our observations are flawed or incomplete.
Many people believe that extraterrestrial life exists and that there are many planets in our own galaxy that harbor life. The idea that life is common everywhere and propelled from star to star by the pressure of starlight was proposed by Svante Arrhenius, who called it " panspermia," but this hypothesis is now in disfavor.
Some believe that our current knowledge of both chemistry and of biology strongly indicates that life is an exceptionally improbable thing to arise spontaneouslyAbiogenesis in its most general sense, is the hypothetical generation of life from non-living matter. Today, the term is primarily used in the context of biology and the origin of life. Some confusion exists on this topic, because early concepts of abioge. "Strong life" proponents counter that because life arose on Earth as soon as the crust cooled, life itself must be intrinsically linked with terrestrial planet formation. Current data on this issue seems to support this second view or a related hypothesisA hypothesis is a proposed explanation for a phenomenon. In early usage, a hypothesis was a clever idea or convenient mathematical approach that would simplify calculation but did not necessarily have any reality at all. This is the sense in which Cardina that life originated elsewhere within the solar system and was transported to the Earth by a meteoriteA meteorite is a relatively small extra-terrestrial body that reaches the Earth's surface. While in space these bodies are called meteoroids. These are "small" asteroids, approximately boulder-sized or less, which are generally fragments resulting from th. The fact that signs of life on Earth seem to be present almost as soon as it cooled enough to support it, that life has been found in a variety of environments once thought incapable of supporting it, that planet formation seems to be fairly common, and that conditions to support bacterial life seem to exist elsewhere in our own solar system all support the position that life should be fairly common. A statisticalStatistics is the science and practice of developing human knowledge through the use of empirical data. It is based on statistical theory which is a branch of applied mathematics. Within statistical theory, randomness and uncertainty are modelled by proba analysis that treats the question of life arising on a planet like winning a lotteryA lottery is a popular form of gambling which involves the drawing of lots for a prize. Some states forbid it, while others endorse it to the extent of organizing a national lottery''. The Lottery is also the name of a famous Shirley Jackson short story w—and generalizing from the special case that, on the only terrestrial world we have seen, the lottery was won—some astrobiologists have concluded that there seems to be at least a one-in-eight chance per billion years of "appropriate" conditions that life will form.
As for the Earthly origin of lifeOrigin of life can have different meanings depending on the context: Origin of life focuses on modern scientific research on the origin of life. Panspermia is a theory that suggests that the seeds of life are prevalent throughout the universe and life on, it now seems fairly certain that it began within our solar system. The harsh radiation of interstellar space coupled with the extremely low probability that any extra-solar rocks capable of protecting life in the harsh inter-stellar environment have ever struck the Earth seem to indicate that, if terrestrial life originated elsewhere, it would almost certainly have to have been carried here on purpose. It is possible that life was brought here, but, if so, it becomes difficult to explain why the first forms of life were simple, single-celled life instead of further up the evolutionary chain, although Timothy Leary has suggested extra-terrestrial seeding of simple amino acids in his Exopsychology , relating evolution and Leary's eight circuit model of human consciousness.
A widely-accepted view is that terrestrial life originated on the Earth itself. Lately, there has been increasingly more support for an idea first mentioned by Lord Kelvin— that life first came about on Mars and was transported to Earth by a meteorite. This latter position is defended on the basis that conditions which might support Earth-compatible life existed within a relatively short distance hundreds of millions of years before the Earth cooled. The more improbable that one deems life beginning spontaneously, the more likely it becomes that life arose first on Mars.
The issue of whether intelligent life develops as readily as simpler forms is still an open question.