Rare Earth hypothesis
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In planetary astronomy and astrobiology, the Rare Earth hypothesis argues that the origin of life and the evolution of biological complexity, such as sexually reproducing, multicellular organisms on E
The Rare Earth hypothesis argues that planets with complex life, like Earth, are exceptionally rare.
Dense centers of galaxies such as NGC 7331 have high radiation levels hostile to complex life.
According to the Rare Earth hypothesis, globular clusters are unlikely to support life.
Planets of the Solar System, shown to scale. Rare Earth argues that complex life cannot exist on giant planets such as Jupiter and Neptune or smaller planets such as Mars and Mercury.
Fermi paradox
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The Fermi paradox is the seeming inconsistency between the lack of evidence of extraterrestrial civilizations and the apparently high likelihood of their existence.
Rare Earth hypothesis
…astronomer and astrobiologist, both faculty members at the University of Washington. The hypothesis has been argued to be a possible solution to the Fermi paradox. In the 1970s and 1980s, Carl Sagan and Frank Drake, among others, argued that Earth is a typical rocky planet in a typical planetary system, located…
Russian rocket scientist Konstantin Tsiolkovsky
Carl Sagan, seen here beside a Viking lander mockup, first mentioned the paradox in print.
Enrico Fermi (1901–1954)
Radio telescopes are often used by SETI projects.