Dan Goldman (Georgia Tech)

"Surprises in self-deforming systems"

Abstract: Often in classical mechanics we study systems which can be represented by point-like particles and are subject to external forcing. In contrast, in living systems we encounter extended objects which undergo internal forcing to generate cyclic changes in shape or configuration. Such dynamics occur across scales, from proteins undergoing conformational changes to cells crawling on surfaces to centipedes wiggling through soil and debris. The physics of such “self-deforming” systems is remarkably rich, especially when coupled to non-trivial environments. In this talk I will narrate a few examples of surprising emergent dynamics in living and nonliving systems arising from the interplay of traveling waves of body bending and environmental heterogeneities. In particular, I will describe how undulatory limbless robophysical models that mix wave and particle-like properties can mechanically “diffract” in regular arrays of obstacles and exponentially localize in disordered environments. Such insights have proven useful in highlighting the importance of mechanics in living systems, e.g. the role of passive dynamics in the locomotion of snakes and nematode worms in heterogeneous environments. Discovery of principles of self-deforming systems is informing and guiding the potential commercialization of elongate robots that can self-propel effectively in dirty, dull, and dangerous situations.