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Frontiers of the Second Law

Frontiers of the Second Law

This video was recorded at MIT World Series: Meeting the Entropy Challenge. These nine panelists describe ways in which the Second Law of Thermodynamics can be stretched, or applied in less traditional ways. Adrian Bejan has constructed a law that "covers every configuration in physics, from animate, to inanimate, to us, the societal." Bejan demonstrates how his law describes and predicts the tree-shaped flow of all rivers, animal locomotion and human settlement distribution. With it, says Bejan, "thermodynamics becomes a science of systems with configuration…" Bjarne Andresen acknowledges "many fights about the Second Law," before declaring his belief that "entropy survives as a concept, and applies equally in the chemistry lab, to the quantum computer and to black holes." He discusses the importance of carefully defining the system under examination beforehand, "otherwise you get into fights with your neighbors." Miguel Rubi discusses how to use the Second Law to extract information about the evolution of small systems. Unlike "canonical thermodynamics," which describe systems in terms of energy, volume and mass, mesoscopic thermodynamics focuses on systems in terms of positions and movement of particles. Some examples of processes explicable by this kind of thermodynamics include the translocation of ions, RNA unfolding under tension, and muscular contractions. Signe Kjelstrup argues that mesoscopic nonequilibrium thermodynamics (MNET) can address a longstanding problem in classical nonequilibrium thermodynamics, by addressing "activated processes." Biological systems have heat flow, says Kjelstrup, and "that is as of yet not included in the description of enzyme kinetics. It should be there to quantify lost work in these important systems." "An important question arising in nonequilibrium thermodynamics is not just entropy but temperature," says David Jou, in particular, "the physical meaning of temperature." Jou invokes the extended thermodynamics of viscoelastic systems, and looks for a simple model valid for a modest range of equations. Miroslav Grmela suggests that any time one goes from details to some kind of pattern, "there is an entropy involved…by providing some kind of dissipation, some pattern recognition process." Grmela believes that thermodynamics … "find a natural formulation in the setting of contact geometry." Lyndsay Gordon's talk involves Maxwellian valves. He discusses "a machine based on an osmophoretic engine," a simple system with a liquid membrane, solvent and solute, "that is fluctuating completely forever," without information. "This thing goes by itself," he says. Eric Schneider discerns "laws of ecology" in such gradient systems as the energy flow between the sun and earth. "We can determine "…heat and entropy production in the system," as well as "ecological successions and directional processes that directly tie them to Darwinian evolution." He advises his colleagues "to encourage policy makers to use exergy analyses on future energy development projects." Symposium organizer George Hatsopoulos wraps up by noting "that as far as I know in thermodynamics, there is no statement that says the Second Law implies the increase of entropy. The Second Law only says that the entropy cannot decrease, but there's nothing wrong with entropy staying put." We have evidence that in some cases it appears the entropy increases, but that's not the "Second Law."


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