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Astrophysics and Cosmology

Last update: 12 Dec 2024 10:44
First version: 20 August 2007; major expansion, 9 April 2010

A (pardon the expression) large subject, which I like to read about but don't work on. (If nothing else I couldn't take the jokes about my name.)

There are interesting issues of statistical mechanics involved, since there are long-range interactions: gravity falls off only slowly with distance r-2, after all), and, unlike electromagnetism, there are no positive and negative charges which could lead to screening off. This leads to some weird effects, like spontaneous clumping, and possibilities like negative specific heats.

A personal hatred: the anthropic principle. To illustrate: I once happened --- no joke --- to find a twenty dollar bill lying in the street in front of my house. This required an extraordinarily fine adjustment of a huge range of circumstances. Among these, of course, were the incidents of American history such that we use paper money, denominated in dollars, that the twenty is a large but still common denomination, and that Andrew Jackson's portait be on it. This last involves our political history through and indeed since Jackson's time. That political history is incomprehensible without the influence of the Enlightenment, and of the ideological struggles of 17th century England (no Lockean possessive individualism, no Jacksonian democracy). Those struggles were intimately tied to England's political and military history in the 17th century, which is only comprehensible in light of (among much else) the Norman Invasion, which in turn was only possible given the condition of Anglo-Saxon England in 1066, but there would have been no Anglo-Saxon England had there not first been a Roman Britain. There would have been no Roman Britain had Britain not already been partly integrated into the broader trading network, which was largely on account, then, of its metals. So, reasoning anthropically, I can conclude, from my stray twenty, that it was necessary that there be tin in southern Britain.

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