Nature has a way of finding optimal solutions to complex problems. For example, despite the billions of ways for a single protein to fold, proteins always fold in a way that minimizes potential energy. Slime mold, a brainless organism, always finds the most efficient route to a food source, even when presented with an obstacle. A jump rope, when held on both ends, always ends up in the same shape, a curve known as catenary. This kind of optimization is explained by what’s known as a variational principle: any other deformation – or variation – of the shape found by the protein, mold or jump rope would require more energy. Our group has found that some lasers use the same principle. The research is described in Physical Review Letters. This manuscript can be found here. See also a press release from Harvard SEAS here.