Vijay Balasubramanian

New Capabilities

Professor of Physics at University of Pennsylvania

Since Santiago Ramón y Cajal first mapped neurons in 1888, scientists assumed the brain optimizes its wiring by taking the shortest path between connections—the biological equivalent of finding the fastest route on a map. For over a century, that assumption held. Then high-resolution brain imaging revealed something strange: neurons branch at right angles, sprout dead-end buds, and take seemingly inefficient routes. The math didn't fit. In January 2026, researchers at Northeastern University published a paper on the cover of Nature showing why. The mathematics physicists developed in the 1980s to describe vibrating strings in higher dimensions—the foundation of string theory—almost perfectly predicts how neurons, blood vessels, and plant roots actually branch. The brain isn't minimizing wire length. It's minimizing surface area.

Updated Mar 19