Newswise – When humans, animals, and machines move through the world, they’re always pushing against something, whether it’s ground, air, or water. Until recently, physicists thought it was a constant, following the law of conservation momentum. Now, researchers at the Georgia Institute of Technology have proven otherwise – when bodies exist in curved spaces, it turns out they box actually move without pushing against anything.
The findings were published in Proceedings of the National Academy of Sciences on July 28, 2022. In the paper, a team of researchers led by Zeb Rocklin, an assistant professor in Georgia Tech’s School of Physics, created a robot confined to a spherical surface with unprecedented levels of isolation from its environment, so that these curvature-induced effects would predominate.
“We let our shape-changing object move on the simplest curved space, a sphere, to systematically study motion in curved space,” Rocklin said. “We learned that the predicted effect, which was so counter-intuitive that it was dismissed by some physicists, actually happened: when the robot changed shape, it moved slowly around the sphere of in a way that could not be attributed to environmental interactions.”
Creating a Curved Path
Researchers set out to study how an object moves through a curved space. To confine the object to the sphere with minimal interaction or exchange of momentum with the environment in the curved space, they let a set of motors run on curved tracks like moving masses. They then connected this system holistically to a rotating shaft so that the motors always move on a sphere. The shaft was supported by air bearings and bushings to minimize friction, and the alignment of the shaft was adjusted with Earth’s gravity to minimize residual gravity force.
From there, as the robot continued to move, gravity and friction exerted slight forces on it. These forces hybridized with curvature effects to produce strange dynamics with properties that neither could induce by itself. The research provides an important demonstration of how curved spaces can be achieved and how this fundamentally challenges physical laws and intuition designed for flat space. Rocklin hopes that the experimental techniques developed will allow other researchers to explore these curved spaces.
Applications in space and beyond
Although the effects are small, as robotics becomes increasingly precise, understanding this curvature-induced effect may be of practical importance, just as the slight gravity-induced frequency shift has become crucial. to allow GPS systems to accurately transmit their positions to orbiting satellites. Ultimately, the principles of how the curvature of space can be harnessed for locomotion can allow spacecraft to navigate the highly curved space around a black hole.
“This research also relates to the ‘Impossible Engine’ study,” Rocklin said. “Its creator claimed that it could move forward without any propellant. This engine was indeed impossible, but because space-time is very slightly curved, a device could actually move forward without any external force or emitting propellant – a new discovery.
Quote: Shengkai Li, Zeb Rocklin, et al. “Forceless and Impulseless Locomotion via Dissipation: Robotic Swimming in Curved Space via Geometric Phase.” Proceedings of the National Academy of Sciences. DOI: 2200924119.
About Georgia Institute of Technology
The Georgia Institute of Technology, or Georgia Tech, is a top 10 public research university developing leaders who advance technology and improve the human condition. The Institute offers degrees in business, computer science, design, engineering, liberal arts, and science. Its nearly 40,000 students representing 50 states and 149 countries study at the main campus in Atlanta, at campuses in France and China, and through distance and online learning. As a leading technology university, Georgia Tech is an engine of economic development for Georgia, the Southeast, and the country, conducting more than $1 billion in research annually for government, industry, and the society.