People like us, who believe in physics, know that the distinction between past, present, and future is only a stubbornly persistent illusion.
Albert Einstein
Article: Nonequilibrium candidate Monte Carlo is an efficient tool for equilibrium simulation
Jerome P. Nilmeier, Gavin E. Crooks, David L. D. Minh, and John D. Chodera, Proc. Natl. Acad. Sci. U.S.A. (2011) 108(45) E1009-E1018
[ Full text | Journal | Author summary | Errata ]
This was a fun paper that originated in a chance, serendipitous conversation between myself, Jerome and John. We realized that several different Monte Carlo sampling techniques that we had each recently worked on could be unified under a common framework by taking inspiration from nonequilibrium thermodynamics. (I am also particularly satisfied with the joke. I firmly believe every scientific paper should contain one joke, lest we take ourselves too seriously. This one is great because it’s hiding in plain sight.)
Abstract: Metropolis Monte Carlo simulation is a powerful tool for studying the equilibrium properties of matter. In complex condensed-phase systems, however, it is difficult to design Monte Carlo moves with high acceptance probabilities that also rapidly sample uncorrelated configurations. Continue reading
Physics Colloquia @ University College London
“Statistical thermodynamics and the breaking of time-symmetry”,
Gavin E. Crooks
Physics Colloquia, University College London (2011)
Gavin E. Crooks
Physics Colloquia, University College London (2011)
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Here’s to the crazy ones. The misfits. The rebels. The troublemakers. The round pegs in the square holes. The ones who see things differently. They’re not fond of rules. And they have no respect for the status quo. You can quote them, disagree with them, glorify or vilify them. About the only thing you can’t do is ignore them. Because they change things. They push the human race forward. And while some may see them as the crazy ones, we see genius. Because the people who are crazy enough to think they can change the world, are the ones who do.
Invited speaker: FQXi’s Setting Time Aright
“Whither time’s arrow?”
An international and inter-disciplinary meeting investigating the Nature of Time
Foundational Questions Institute
Norway and Denmark,
Aug. 27 – Sept. 1, 2011
Article: On thermodynamic and microscopic reversibility
Gavin E. Crooks, J. Stat. Mech. (2011) P07008
Abstract: The word ‘reversible’ has two (apparently) distinct applications in statistical thermodynamics. A thermodynamically reversible process indicates an experimental protocol for which the entropy change is zero, whereas the principle of microscopic reversibility asserts that the probability of any trajectory of a system through phase space equals that of the time reversed trajectory. However, these two terms are actually synonymous: a thermodynamically reversible process is microscopically reversible, and vice versa.
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We all want progress, but if you’re on the wrong road, progress means doing an about-turn and walking back to the right road; in that case, the man who turns back soonest is the most progressive.
C. S. Lewis
Article: Measures of trajectory ensemble disparity in nonequilibrium statistical dynamics
Gavin E. Crooks and David A. Sivak, J. Stat. Mech.: Theor. Exp. P06003 (2011)
I’ve been meaning to look at the physical significance of f-divergences for some time. These are a class of information type measures that, thanks to the quirks of nonequilibrium thermodynamics, can actually be experimentally measured in real systems. I was finally inspired to write this up due to John Baez, who recently discussed the significance of Rényi entropy to equilbrium statistical mechanics.
Abstract: Many interesting divergence measures between conjugate ensembles of nonequilibrium trajectories can be experimentally determined from the work distribution of the process. Herein, we review the statistical and physical significance of several of these measures, in particular the relative entropy (dissipation), Jeffreys divergence (hysteresis), Jensen–Shannon divergence (time-asymmetry), Chernoff divergence (work cumulant generating function), and Rényi divergence.
Award: Presidential Early Career Awards for Scientist and Engineers (PECASE)
Plenary Talk @ University of Edinburgh
“Near equilibrium measurements of non-equilibrium free energies”
Gavin Crooks
2010 Workshop on
Multiscale Molecular Modeling: Molecular Dynamics, Computational Statistical Mechanics, and Simulation Algorithms
University of Edinburgh.
Gavin Crooks
2010 Workshop on
Multiscale Molecular Modeling: Molecular Dynamics, Computational Statistical Mechanics, and Simulation Algorithms
University of Edinburgh.
Further Reading:
Word of the Day: Super-duper-operator
Super-duper-operator (n): An operator is a linear map that acts on a vector space. A superoperator is an operator of an operator, an operator that acts on a vector space of operators. A super-duper-operator is an operator of an operator of an operator, an operator that acts on a vector space of superoperators.
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Substitute damn every time you’re inclined to write very; your editor will delete it and the writing will be just as it should be.
Mark Twain