Ocean eddies, cosmic black holes may have much in common
Astronomers learn more about the physics of black holes.
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What do black holes and ocean currents have in common? More than meets the eye—according to a new study published by scientists from the University of Miami and the Swiss institution Eidgenössische Technische Hochschule, the movements of a large ocean eddy can fairly closely mimic that of a black hole.
An eddy is a swirling of fluid that occurs when the fluid flows past an obstacle and runs against the greater body of fluid’s reverse current. The larger eddies can extend as much as 90 or more miles in diameter and influence global climate by conveying warm and salty water to cooler locales. The southern hemisphere’s eddies have, incidentally, been increasing in number in recent years, a possible byproduct of global climate change.
Like black holes, ocean eddies may pose a danger to anything in their path. They obviously don’t suck objects into event horizons so dense that time stops and even light cannot escape, like black holes. But they do stimulate extreme weather events. And the force of their currents does cause the drowning deaths of unsuspecting swimmers who get caught in them.
Ocean eddies have been very hard to identify, as their boundaries don’t present clearly visible start and end points. The Miami and Swizerland-based science team devised a solution, however. In their study, which was published in the Journal of Fluid Mechanics, they presented a mathematical technique for pinpointing the coherent water islands within oceanic turbulence. It enabled them to isolate water eddies within surfaces of water presented to them via satellite images. And it is based on comparing the motion of ocean eddies to that of black holes.
They determined that eddies possess surrounding barriers similar to those of black holes. Light approaching a black hole is gone if it reaches the edge of it, but if it hits the edge at a certain angle, it may instead bend dramatically and form a circular orbit, eventually returning to its original position. A barrier surface of light photons, called a photon sphere, then emerges.
Certain large eddies have similar barriers, the team wrote. They consist of fluid particles that move around in loops with so much force that nothing can escape from them. If we look for these barriers, we will more easily spot the ocean eddies that created them.
The team’s results may be a boon to many future ocean studies. Longstanding questions regarding climate, the spread of environmental pollutants, and other matters may be more solvable based on this study’s findings.