Topological antiqued mechanical toy
Hirofumi Wada, Hayato Mizobata, Shuto Ueno, Taiju Yoneda

TL;DR
This paper investigates the physical principles behind Jacob's ladder, revealing its topological and mechanical properties through experiments, simulations, and theory, and uncovering its unique coexistence of kink and antikink waves.
Contribution
It combines experimental, numerical, and theoretical analysis to uncover the topological and mechanical nature of Jacob's ladder, a classic children's toy.
Findings
The toy is bistable under gravity, acting as a topological soliton.
Kink and antikink waves coexist due to the toy's floppiness, unlike in topological chains.
Experimental observation of pair annihilation of kink and antikink waves.
Abstract
{\it Jacob's ladder} -- a classic children's toy -- is a simple mechanical frame comprising rigid blocks connected by strings that shows curious unidirectional flipping waves. Nonetheless, its physical origin remains elusive. By combining experiment, numeral simulation, and theory, we show that understanding the underlying design principle of this toy requires diverse physical ideas. First, we conduct a water-tank experiment that excludes the domino-like mechanism, thus defying widespread expectations. Subsequently, we analytically demonstrate that the toy is bistable under gravity, thus implying its kink wave as a class of topological solitons. The waves are surprisingly reminiscent -- both experimentally and theoretically -- to those in the Kane--Lubensky topological chain, owing to the stiffening of zero modes by the pretension under gravity. However, a close examination based on the…
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
