Modeling Maxwell’s Demon

The interesting article “Engineering Maxwell’s demon” by Zhiyue Lu, Dibyendu Mandal, and Christopher Jarzynski in the August 2014 issue (page 60 ) includes a link to a video, created using the three-dimensional animation software Blender, of the device. I’ve used GlowScript to make an interactive version at http://www.glowscript.org/#/user/Bruce_Sherwood/folder/Pub/program/MaxwellDemon .

The program lets the user zoom and rotate to inspect the device, and it plots the demon’s rotational velocity component as a function of time. The plot demonstrates the counterclockwise bias over long times that the authors describe. A user can observe the increased informational entropy in the paddle positions. A modern browser that supports the 3D graphics library WebGL and a graphics card with graphics processing units are required; click “Help” in the upper right corner for details on system requirements. Click “Edit this program” to see the code, which is short for a program of this complexity. I thank the article’s authors for helpful advice.