Researchers from the Georgia Institute of Technology have proven that robotic motion in curved spaces moves without pushing against something. But physicists until recently believed that when humans, animals, and machines move throughout the world, they always push against something, whether it’s the ground, air, or water that is constant, following the law of conservation of momentum.
According to the study published in Proceedings of the National Academy of Sciences on July 28, 2022, the team of researchers led by Zeb Rocklin, assistant professor in the School of Physics at Georgia Tech created a robot confined to a spherical surface with unprecedented levels of isolation from its environment, so that these curvature-induced effects would predominate.
Stating that we let our shape-changing object move on the simplest curved space, a sphere, to systematically study the motion in curved space, Rocklin further said, “We learned that the predicted effect, which was so counter-intuitive it was dismissed by some physicists, indeed occurred: as the robot changed its shape, it inched forward around the sphere in a way that could not be attributed to environmental interactions”.
The goal of the research was to determine how an object traveled across a curved area. They let a set of motors travel along curved rails as moving masses in order to restrict the object on the sphere with the least amount of contact or momentum exchange with the surroundings. In order to ensure that the motors constantly move on a sphere, they next connected this system holistically to a rotating shaft. In order to reduce friction, the shaft was supported by air bearings and bushings, and the position of the shaft with respect to Earth’s gravity was altered in order to reduce any remaining gravitational force.
Gravity and friction began to have a little effect on the robot as it moved forward after that. These forces hybridized with the curvature effects to create a peculiar dynamic that has qualities that neither force could have created on its own. The study offers an important illustration of how curved spaces are possible and how they fundamentally defy laws of physics and common sense that are based on flat space. Rocklin expects that future researchers will be able to investigate these curved areas using the experimental methods that have been created.
Although the effects are negligible, as robotics becomes more accurate, understanding this curvature-induced effect may become extremely relevant from a practical standpoint, much like how the slight frequency shift brought on by gravity became essential for GPS systems to accurately transmit their positions to orbital satellites. Ultimately, the principles of how a space’s curvature can be harnessed for locomotion may allow spacecraft to navigate the highly curved space around a black hole.
According to Rocklin, this research also relates to the ‘Impossible Engine’ study. “Its creator claimed that it could move forward without any propellant. That engine was indeed impossible, but because spacetime is very slightly curved, a device could actually move forward without any external forces or emitting a propellant — a novel discovery”, said Rocklin.