review-notes-09 - 1 H A&S 222a Energy and...

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Unformatted text preview: 1 H A&S 222a Energy and Environment: Life Under the Pale Sun P.B. Rhines, Marcela Ewert 1 June 2009 REVIEW: There are 4 sub-regions in this course: 1. energy in nature, 2. the global environment 3. human energy use 4. life and energy at the rim of the Arctic Introduction. This review is not meant to describe everything of importance in the course, but may help pull some of the ideas together. The four sub-regions above are related in many ways; indeed that is the reason for studying them together. Here are some of these relationships. In looking for basic principles that lie at the basis of life on Earth, energy , as it is described in physics and chemistry, is a strong candidate. There are certainly others: the structure and replication of the spiral DNA molecule provides a principle that underlies life in all its forms. There are other candidates for basic principles underlying the environment, for instance Darwins model of evolution of species. DNA is the engine that drives evolution and the books Richard Dawkins argue that evolution is a nearly universal idea governing life; it tries to answer the question, why are we here?; I think it better to ask how did we come to be here instead, so as not to go beyond questions of science. Others (not Dawkins, particularly James Lovelock and his Gaia description of Earth) argue even further that evolution and natural selection answer even greater questions, like why is the Earth the way it is, a blue planet with its rocks and seas and ecosystems, in some reasonably stable state, rather than a parched, lifeless planet like Mars or Venus. Compared to DNA and evolution, energy seems a bit dumb, as in the difference between studying a great oil painting and studying the petrochemicals that make oil paints. Yet we physicists persist. Biology is great, and it paints rich pictures. But it paints them with energy. And, our recent understanding of the microscopic world of molecules makes energy cycles understandable. At the same time we introduced energy, we started reading environmental/cultural history (Bill McKibbens The End of Nature, J.R.McNeills Something New Under the Sun, an Environmental History of the 20 th Century, Jared Diamonds Collapse: How Societies Choose to Succeed or Fail, and Knud Rasmussens journals of Artic enthnology seen in the 1920s Thule Expeditions, in Gretel Ehrlichs This Cold Heaven: Seven Seasons in Greenland, Harald Sverdrups Among the Tundra People of the Siberian Chukchi Coast ). Vaclav Smils Energy and John Hartes Consider a Spherical Cow provided more of the science core. 1 . Energy in nature . We followed energy from its generation in the sun (by fusion of the simplest element. hydrogen into the next simplest element, helium. This is a nuclear reactor, which physicists have reproduced in the H-bomb, and now are trying to tame to generate useful energy. Most of the energy used on Earth comes from this source, with a bit extra welling up from the Earths core. Earth comes from this source, with a bit extra welling up from the Earths core....
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review-notes-09 - 1 H A&S 222a Energy and...

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