2025/10/08 by Falko Ziebert, Ziebert, Falko, Igor M. Kulić +1
Engineering · Physics and Astronomy · #Advanced Materials and Mechanics #Biological Physics (physics.bio-ph) #FOS: Physical sciences #Micro and Nano Robotics #Modular Robots and Swarm Intelligence #Soft Condensed Matter (cond-mat.soft)
paper · pdf · doi:10.48550/arxiv.2510.06830
openalex publication_date 2025/10/08 · openalex created_date 2025/10/18 · openalex updated_date 2026/07/28
There is this old, eternal question: Why don't animals have wheels? In this perspective we show that they actually do. And they do so in a physically extraordinary way -- by combining incompatible elasticity, differential geometry and dissipative self-organization. Nature's wheel -- the ``wheel-within'' -- has been mysteriously concealed in plain sight, yet it spins in virtually every slender-body organism: in falling cats, crocodilians spinning to subdue their prey, rolling fruit-fly larvae, circumnutating plants and even in some of our own body movements. Flying somehow under the radar of our cognition, in recent years the wheel-within also tacitly entered the field of soft robotics, finally opening our eyes for its ubiquitous role in Nature. We here identify its underlying physical ingredients, namely the existence of a neutrally-stable, shape-invariant and actively driven elastic mode. We then reflect on various man-made realizations of the wheel-within and outline where it could be spinning from here.