Scientific theories make predictions about the real world that depend upon our knowing certain parameters governing the behavior. Sometimes, like in Newton's laws, these parameters (the force due to gravity and the masses of the objects) are known. But in many cases, some or many of the parameters are either unknown or significantly uncertain.
Some years back, Colin Hill (then a Physics graduate student of mine, now CEO of Gene Network Sciences) got interested in biology. He dragged me out to talk with Rick Cerione (then in Molecular Medicine at the Vet college) and his student Guillermo Calero about how proteins interact to transmit signals inside cells (and how, when they mutate, cells can become cancerous). Another student, Kevin Brown, soon got involved, and we stumbled onto the existence of sloppy models...
|Sloppy models are multiparameter models, whose behavior depends only on a few stiff combinations of parameters, with many sloppy parameter directions largely unimportant for model predictions. We've found them ubiquitous in systems biology, in physics and in mathematics.|