Here is classic (and difficult) physics problem that poses an interesting question: Take two points in space, Point 1 and Point 2. What is the path from point 1 to 2 that a frictionless object could ...
Study first author Manolo Rivera Lam (left) and Andrea Alberti (right) at the Institute of Applied Physics at the University of Bonn. Credit: © Volker Lannert/Uni ...