The discussion of whether the aliens exist was sparked in the 20th Century when the people started to spot extraterrestrial being on Earth and UFOs (Unidentified Flying Objects) started to be identified in pictures and movies.Many popular scientists of the 21st Century like Stephen William Hawkins believe that aliens do exist somewhere in the universe but many others have presented strong theories about their inexistence.

This paper will however present the argument that the aliens do not exist.Life as a Rare PhenomenonLife may not exist on other planets in the universe because there are not many planets like Earth where there is a suitable environment. This is the reason why our planet is called the Rare Earth. However, life itself is known to be a rare phenomenon which contributes to the notion that aliens do not exist (Webb).Life emerging from non-living materials is a miracle and hence complex life-forms evolving from non-living materials are not likely to occur.

All the scientists believe that water as a solvent is required for life to occur in nature and every life is carbon based.However, some have argued that life can be based on silicon and other chemicals rather than carbon and water could be replaced by other solvents like methane. Nevertheless, this is a failure of imagination as it is very difficult to conceive biochemistry without carbon or water as these elements are necessary for the existence of life (Webb).A remarkable argument presented by Protagoras suggests us that mankind is most probably alone in the universe.

The numbers of difficult steps which hinder the road to development of life make this argument more strong (Webb).Works CitedWebb, Stephen. Where is everybody? New York: Copernicus Books, 2002.