Category Archives: Uncategorized

A 10-minute video summarizes this article: tinyurl.com/AFlatEarthModel A one-hour physics colloquium based on this article. 50-minuta versio tinyurl.com/PlataTero, kun partopreno de Derek Roff. In the US and in Britain there are organized groups of people who strongly believe that the … Continue reading →

Consider the following interaction between a proton and an electron: The electric forces between the proton and electron exhibit “reciprocity.” That is, the electric force that the proton exerts on the electron is equal in magnitude and opposite in direction … Continue reading →

People sometimes ask, “What is the source of the energy expended by a magnet to attract another magnet, giving it kinetic energy? After all, the magnet doesn’t get colder.” The energy aspects of a magnet accelerating another magnet can indeed … Continue reading →

Because the magnetic force on a moving charge is perpendicular to the velocity, the work done by a magnetic force is zero. However, in a multiparticle system it can happen that magnetic forces can rearrange the energy within the system, … Continue reading →

A colleague identified a puzzle concerning Faraday’s law. A circular loop at the center of a long solenoid with time-varying magnetic field will run a current due to the emf, which is the path integral of the (curly) non-Coulomb electric … Continue reading →

Here is a time line for the development of VPython, an extension to the Python programming language that makes it unusually easy to generate navigable real-time 3D animations (vpython.org). 1997: While at Carnegie Mellon, after writing a volume on introductory … Continue reading →

I have a story to tell about pseudowork, the integral of the net force along the displacement of the center of mass, which is different from the true work done by a force on a system, which must be calculated … Continue reading →

In 1966-1969 I was active in an experimental particle physics group at Caltech and taught intro physics using the Feynman Lectures on Physics as the textbook, which was a fantastic experience. I often saw Feynman at lunch in the Caltech … Continue reading →

David Hestenes’ goal for geometric algebra is to subsume under one umbrella many different kinds of mathematics used by scientists and engineers (see the Hestenes web site, and especially his Oersted Medal Lecture). The key to this unification is to … Continue reading →

A talk given at a Santa Fe Science Cafe, 2013 Jan. 16 Abstract of the talk Video of the talk Interview on KSFR radio (15 minutes; choose the 3rd audio option) The great discovery by Maxwell about 150 years ago … Continue reading →