Lecture Summary 11

Lecture Summary 11 - Lecture Summary(11/23 What do we mean...

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Lecture Summary (11/23) What do we mean when we say "life?" We have one example—life here on the Earth. Much of the discussion around whether or not extraterrestrial life exists depends on whether we are "typical" or a "chance occurrence." Life on Earth is carbon-based. Chemically carbon can form 4 bonds with other atoms and therefore can form complex molecules, chains and rings. Life processes are complex. Carbon chemistry with water serving as the medium of exchange has the advantage of also being fairly abundant as chemicals go. Organic molecules exist in meteorites and the ISM. Experiments have been performed in laboratories to simulate the conditions on ancient Earth—remember, the rock record indicates our atmosphere lacked significant quantities of oxygen originally. All of the building blocks of life (proteins, amino acids, nuclei acids) have been produced in such experiments. Given a billion years after the Earth's formation, life arose here. A
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This note was uploaded on 02/01/2011 for the course ASTR 101 taught by Professor Deming during the Spring '07 term at Maryland.

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Lecture Summary 11 - Lecture Summary(11/23 What do we mean...

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