“For relativity, it’s very important,” said physicist Martin Bojowald at Penn State University, who was not involved in the new work. “There are very few classic tests of relativity. It now seems that we are pretty close to actually using this.”
Black holes are greedy beasts. Not only do they attract matter so strongly that even light can get trapped in their great gravitational bellies, they also grab hold of the fabric of space-time in their vicinity. When a black hole spins — and astronomers expect that most do, although none have been definitively observed — it swirls its surrounding space-time around with it like water spiraling around a drain.
This phenomenon, called frame-dragging, has been proven to work even around bodies as small as Earth. Observations of two Earth-orbiting satellites over the last few decades show that the satellites drag by several feet per year as Earth’s spin tows the fabric of space and time in circles.
“If you can see it, such a tiny little effect from this minute mass that the Earth has compared to a black hole, how much easier would it be to see it around a black hole?” said space physicist Bo Thidé of the Swedish Institute of Space Physics, coauthor of a paper published online February 13 in Nature Physics. “That’s how we started.”
From other researchers’ experiments using lasers and lenses, Thidé and colleagues knew that light traveling in a straight line can be forced into a spiral if sent through the right kind of lens. The twisted beams come out looking like corkscrew-shaped fusilli pasta, Thidé says.
Read more at Wired
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