5:00 pm Wednesday, February 10, 2010
umrg: Math Club: From quantum to classical: On the emergence of physical laws and the underlying mathematics by Thomas Chen (UT Austin) in RLM 12.104
While modern quantum theory describes matter as it appears in everyday life with incredible accuracy, and is ``the correct theory'', classical physical theories such as Newtonian mechanics, classical electrodynamics, or fluid dynamics are still as widely used and powerful as ever. As experience shows, it is not necessary to invoke quantum mechanics to determine the orbits of the planets, to design the wings of an airplane, or to build an electric engine. But why not? In this talk, it is described how certain examples of (semi)classical theories in physics are derived from first principles in quantum mechanics, in the process of which the former become independent of the latter. This typically involves a transition from small to large, from complex to average, or more generally, from one scale to a fundamentally different one. The examples addressed here allow for a fully mathematically rigorous analysis, based on a combination of techniques stemming from partial differential equations and quantum field theory. Submitted by
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