UW Cosmology of Life

COSMOLOGY OF LIFE

This website presents class materials for the senior honor�s seminar called Cosmology of Life.

The science of cosmology encompasses the study of the history of the universe. The standard model for teaching cosmology covers the origin of the universe (Big Bang) to the formation of large-scale structure (galaxy formation). Cosmology and astronomy do not usually have as much to say to students about the evolutionary history of life. These sciences might cover the natural cosmic formation of amino acids in space, the seeding of planets with amino acids and water by meteors and comets, and the pre-biotic conditions for life-formation in the ancient oceans. Modern astronomy books may cover the first origins of life, but tend to leave the rest of the history of life to the biology teachers. Biology books, on the other hand, tend to leave us blissfully unaware of the historical cosmic processes on which life depended for its development, and which continued to affect the evolution of life over the ages of the geological time scale. This course presents one seamless history of events from the big bang to modern times, showing cosmology, astronomy, planetary science, atmospheric science, and evolutionary biology not as separate disciplines, but as intertwined parts of one grand history of life.

The standard teaching of biology tends to start around 3.8 billion years ago with early evidence of life on Earth (skewed carbon isotope ratios in rocks from Greenland). But of course the universe is much older (at least 13.7 billion years old) and life was profoundly influenced by earlier events. Time, space, energy, and baryonic matter all emerged from the big bang. The cosmic abundance of hydrogen was shaped by the big bang. Stars had to form first, live and die, to create the necessary heavier elements on which life depends (atoms like carbon, nitrogen, and oxygen that were not created in the big bang but formed later during stellar evolution). Biologists tend to view the element beryllium as a cell poison, not as a required element for life. Yet beryllium is essential in the stellar nuclear fusion processes leading to the production of carbon atoms. Without beryllium there would be no common carbon, and life would not exist. Life further required a series of planetary processes for setting up the initial suitable conditions: accretion, volcanism, plate tectonics, bombardment by water and amino acid-bearing bodies, outgassing to produce atmosphere and oceans, and the formation of a protective magnetosphere.

Life on Earth continued to be affected by cosmic processes, and we remain fully depend on stars for our existence. All life is built, quite literally, from the ashes of a long-deceased red giant star the blasted its atoms into space in a catastrophic supernova explosion. Life remains largely dependent on stellar energy from our sun (the nearest star) to drive terrestrial ecosystems. Over time, life on Earth has been hugely influenced by ongoing cosmic processes. Volcanic activity, along with accretion and bombardment, created the atmosphere and oceans, allowing life to get started. But volcanism did not go away - it continued to drive the movement of the Earth�s continental masses (plate tectonics). In Precambrian times, this process heaved life into a deep freeze, by aligning the continents near the equators, and creating condition for prolonged global ice ages (Snowball Earth). Yet volcanoes continued to provide the heat for life to survive, and continued to drive the continents into new configurations and eventually again into conditions favorable for life. At the end of the Permian period (about 248 million years ago) the continents again conspired in a massive crime: the formation of the super-continent Pangaea massively destroyed coastal marine habitats, and life on Earth experienced the greatest mass extinction ever recorded (up to 95% of marine species went extinct).

Life was profoundly affected by other cosmic processes as well. The late heavy bombardment, 3.9 billion years ago, pounded the Earth with debris from the outer reaches of the solar system, and produced most of the visible craters of the moon. But that same debris was laced with water ice, trace minerals, and amino acids � the very stuff needed for oceans and life to form. Bombardment has slowed enormously over time, but it has not stopped. Meteors continue to fall, and from time to time something much larger (a comet or asteroid impact). These cosmic events have been implicated in some of the major historical events in the history of life on Earth. Best known, perhaps, is the late Cretaceous period impact that may have helped finish off the last of the big dinosaurs, and so set up conditions allowing mammals to finally diversify. Now asteroid impacts are being implicated as significant events at the end of several geological time periods. Some have suggested that there may be a repeating pattern to this bombardment averaging about once every 26 million years (periodic mass extinctions).

My point simply is that biology and cosmology are deeply interwoven historically, and should not be viewed as separate disciplines. Evolutionary biology makes more sense when viewed in the framework of cosmology, astronomy, planetary science, and atmospheric science. This is the key theme of my class, Cosmology of Life.

Contact information:

Professor Scott R. Shaw

U.W. Insect Museum

Department of Renewable Resources

University of Wyoming

1000 East University Avenue

Laramie, Wyoming 82071-3354 U.S.A.

braconid@uwyo.edu

List of topics and other useful site links:

Time Travel, the nature of time

Big Bang

Stellar Evolution, Origin of Solar System, Earth, and Moon