If the astronauts suddenly drifted into the interstellar void, they would have to propel their bodies to safety, kicking and swinging their limbs towards heaven in the void.
Unfortunately for them, physics is unforgiving, leaving them floating hopelessly forever. If only the universe was warped enough, their defeat might not have been in vain.
Centuries before we went to tow the Earth, Isaac Newton briefly explained why things move. Whether it’s expelling gas, pushing it against solid ground, or swinging a flipper against a liquid, the momentum of the action is maintained by the number of elements involved, creating a reaction that propels the body forward.
Exhale the air around the bird’s wings or the water around the fish’s tail, and the effort of each flap will propel in one direction as with the other, leaving the poor animal flapping feebly with no net movement to its destination.
In the early twenty-first century, consider physicists a loophole for this rule. If the three-dimensional space in which this movement occurs is curvilinear, changes in the shape or position of objects do not necessarily follow the usual rules of how momentum is exchanged, which means that there is no need for a motive.
The warped geometry of space-time itself might mean the deformation of an object — a right kick, a flutter, a flutter — only that you might notice a subtle net change in its position.
On the other hand, the idea that the curvature of space-time affects motion is as easy as watching a rock fall to the ground. Einstein discussed this more than a century ago in his Theory of general relativity.
But showing how rolling hills and valleys in curvy space can affect the body’s ability to propel itself is another ball game.
To put this in action without traveling to the nearest space warp. Black hole A team of researchers from the Georgia Institute of Technology, Cornell University, the University of Michigan and the University of Notre Dame built a model of curved space in the laboratory.
The mechanical version of their spherical chamber consists of a set of motor-driven blocks that run along a curved rail track. Attached to a rotating arm, the entire setup is positioned so that the gravitational pull and frictional pull are minimal.
- A “space” swimmer who moves on a rotating arm trajectory. (Georgian Technology)
While mass doesn’t break with the physics that dominates our rather flat universe, the system is balanced so a bend in the path would have the same effect as space warping dramatically. Or so the team hoped.
As the robot moves, the combination of gravity, friction and bending is combined into motion with unique properties that are best described by the geometry of space.
“We let our shape-shifting object move in the simplest curved space, a sphere, to systematically study motion in curved space,” says Georgia Tech physicist Zip Rocklin.
“We learned that the expected effect, which is so counterintuitive that some physicists have rejected it, did occur: when the robot changes shape, it moves forward around the sphere in a way that cannot be attributed to environmental interactions.”
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Even if the effect is small, using experimental results that are in line with this theory could help place the technology better in areas where the curvature of the universe is significant. Even in a gentle regression like Earth’s gravity, understanding how restrained motion can change ultra-fine location over the long term can become even more important.
Of course, physicists went the route without fuel. ‘Impossible Engine’ Before. Minor hypothetical powers in experiments have their way of coming and going, resulting in endless debate about the validity of the theory behind them.
More research using more precise machines could reveal more insights into the complex effects of swimming at the sharp edges of the universe.
For now, we can only hope that the gentle tilt of the void surrounding the hapless astronaut will be enough to see him reach safety before the oxygen runs out.
This research was published in PNAS.