Carbon-based life

Carbon forms the key component for all known life on Earth. Complex molecules are made up of carbon bonded with other elements, especially oxygen, hydrogen and nitrogen, and carbon is able to bond with all of these because of its four valence electrons. Carbon is abundant on earth. It is also lightweight and relatively small in size, making it easier for enzymes to manipulate carbon molecules. It is often assumed in astrobiology that if life exists somewhere else in the universe, it will also be carbon based. Critics refer to this assumption as carbon chauvinism.

Characteristics

"What we normally think of as 'life' is based on chains of carbon atoms, with a few other atoms, such as nitrogen or phosphorus", per Stephen Hawking in a 2008 lecture, "carbon [...] has the richest chemistry." The most important characteristics of carbon as a basis for the chemistry of life are, that it has four valence bonds, that the energy required to make or break a bond is at an appropriate level for building molecules, which are stable and reactive. Because carbon atoms bond readily to other carbon atoms allows for the building of arbitrarily long complex molecules and polymers.

Neil deGrasse Tyson

Neil deGrasse Tyson (/ˈniːəl dəˈɡræs ˈtaɪsən/; born October 5, 1958) is an American astrophysicist, cosmologist, author, and science communicator. Since 1996, he has been the Frederick P. Rose Director of the Hayden Planetarium at the Rose Center for Earth and Space in New York City. The center is part of the American Museum of Natural History, where Tyson founded the Department of Astrophysics in 1997 and has been a research associate in the department since 2003.

Born in New York City, Tyson became interested in astronomy at the age of nine after a visit to the Hayden Planetarium. After graduating from the Bronx High School of Science, where he was editor-in-chief of the Physical Science Journal, he completed a bachelor's degree in physics at Harvard University in 1980. After receiving a master's degree in astronomy at the University of Texas at Austin in 1983, he earned his master's (1989) and doctorate (1991) in astrophysics at Columbia University. For the next three years, he was a postdoctoral research associate at Princeton University, and in 1994, he joined the Hayden Planetarium as a staff scientist and the Princeton faculty as a visiting research scientist and lecturer. In 1996, he became director of the planetarium and oversaw its $210-million reconstruction project, which was completed in 2000.