# Mathematical Digest

### Short Summaries of Articles about Mathematics

in the Popular Press

"Lightning Forks Illuminated," by Philip Ball. *Nature Science Update,* 10 April 2002.

The apparent similarities in branching in systems as diverse as blood vessels,diverging streams, and lightning forks has captivated many imaginations. NowDutch researchers have given a mathematical explanation for these similarities.Their study shows how lightning forking arises out of a condition calledLaplacian instability, which was already known to be behind many other kinds ofbranching behavior.

*--- Rafe Jones*