This blog is intended as a repository of bits and pieces for my friends, students and anybody else interested. In particular, it contains applets and illustrations emerging from conversations, seminars and classes.

The audience: anybody interested in physics, geometry and algebra.  The ideas will be presented in an expository style.  An interested reader will be directed to further literature.

Recent recurring subjects: geometry and relativity, celestial sphere, a puzzle. Near future: Apollonian disk packing, Lie algebras, ...

Frequency: About once a week (intended).

The tab "Geometry" will take you to the list of illustrations from different posts for a quick access

One of the inspirations for this blog was the geometry program Cinderella created by Ulrich Kortenkamp and J├╝rgen Richter-Gebert.  So many ideas can be quickly conveyed by a simple interactive applet that it would a sin not to use it outside the basic geometry.  Unfortunately Cinderella was hit by the ban on Java in web pages.  Fortunately, Geogebra is an equally capable program, which is based on Javascript, hence was not affected by the ban.  And this is the one I will be using until Cinderella fixes the problem.