April 2019 Issue of American Journal of Physics

April 2019 Issue,
Volume 87, No. 4


Analytic formula for the geometric phase of an asymmetric top

The motion of a handle spinning in space has an odd behavior. It seems to unexpectedly flip back and forth in a periodic manner as seen in a popular YouTube video (“Plasma Ben, Dancing T-handle in zero-g, HD,” ). As an asymmetrical top, its motion is completely described by the Euler equations and the equations of motion have been known for more than a century. However, recent concepts of the geometric phase have allowed a new perspective on this classical problem. Here, we explicitly use the equations of motion to find a closed form expression for the total phase and hence the geometric phase of the force-free asymmetric top and we explore some consequences of this formula with the particular example of the spinning handle for demonstration purposes. As one of the simplest dynamical systems, the asymmetric top should be a canonical example to explore the classical analog of the Berry phase.



Analytic formula for the geometric phase of an asymmetric top by Nicholas A. Mecholsky. DOI:  10.1119/1.5093302

Ping-pong ball cannon: Why do barrel and balls fly in the same direction? by Thorsten Pöschel, Daniel S. Nasato, Eric J. R. Parteli, Jason A. C. Gallas, and Patric Müller. DOI: 10.1119/1.5088805

The fortuitous chain reaction by J. M. Pearson. DOI: 10.1119/1.5089204

Levitation? Yes, it is possible! by Alberto T. Pérez, Pablo García-Sánchez, Miguel A. S. Quintanilla, and Armando Fernández-Prieto. DOI: 10.1119/1.5092451

Measuring the magnetization of a permanent magnet by B. Barman, and A. Petrou. DOI: 10.1119/1.5092452

Causality and dispersion relations by Tejas Dethe, Harmeet Gill, Dylan Green, Andrew Greensweight, Luis Gutierrez, Muyuan He, Toshiki Tajima, and Kevin Yang. DOI: 10.1119/1.5092679

Electron mobility in graphene without invoking the Dirac equation by Chaitanya K. Ullal, Jian Shi, and Ravishankar Sundararaman. DOI: 10.1119/1.5092453

Reconciliation of the Rosen and Laue theories of special relativity in a linear dielectric medium by Michael E. Crenshaw. DOI: 10.1119/1.5092584

An experimental information gathering and utilization systems (IGUS) robot to demonstrate the “physics of now” by Ronald P. Gruber, and Ryan P. Smith. DOI: 10.1119/1.5093293


Combined demonstration of non-viscous and viscous flow by Stephen M. Durbin. DOI: 10.1119/1.5086010

Computational Physics

Statistical physics meets biochemistry: Wang-Landau sampling of the HP model of protein folding by Alfred C.K. Farris, Thomas Wüst, and David P. Landau. DOI: 10.1119/1.5093292

Book Reviews

What is Real? The Unfinished Quest for the Meaning of Quantum Physics by Christopher A. Fuchs. DOI: 10.1119/1.5089208

Beyond Weird: Why Everything You Thought You Knew About Quantum Mechanics is Different byMano Singham. DOI: 10.1119/1.5091791


American Journal of Physics 87, 320 (2019); https://doi.org/10.1119/1.5093296

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