A PHYSICIST HAS EXPLAINED AN OBSERVATION BY LEONARDO. Instapundit called attention to a recent paper by a physicist, Christophe Eloy, which provides a mathematical explanation for an observation made by Leonardo da Vinci which has never been satisfactorily explained. This article in Wired by Kim Krieger of ScienceNOW describes what Eloy has done. Graphic artists routinely use Leonardo’s rule to create realistic computer-generated trees. “The rule says that when a tree’s trunk splits into two branches, the total cross section of those secondary branches will equal the cross section of the trunk.” If the two branches split into four, the total cross section of those will equal the cross section of the trunk. The article has a mathematical formula to express the rule and some helpful illustrations. The rule actually gives an approximation; the most accurate approximation varies with the species of the tree.
The explanation for why the tree growth fits the formula is that the trees are optimizing resistance to wind forces. This means that research relating to the Eiffel Tower and skyscrapers is now relevant to tree growth.