While you can twist physical materials into a Möbius strip — to make chairs, tables and even buildings — until now it’s been impossible to do the same with light. But researchers from the Max Planck Institute for the Science of Light have changed that.
It was suggested back in 2005 by Isaac Freund at Bar-Ilan University in Israel that the polarisation of light -- which describes the direction the waves oscillate -- could become twisted. Peter Banzer, the Max Planck researcher, built on this idea to create an experimental set-up capable of forming a Möbius strip.
It uses two polarised beams of light which are allowed to interfere with each other. In fact, they're bounced off a gold bead smaller than the wavelength of, creating a looped polarisation pattern with three or five twists -- very similar to a Möbius strip. If you're being pedantic, you'd correctly point out that a Möbius strip actually has one twist, and you'd be right, but give these guys a break. Speaking to New Scientist, Banzer explained:
"These results are the first (experimental) proof that Möbius strips really exist, which has been a decade-long question in the community. These findings emphasise the richness of light and its properties."
It's a neat trick, for sure, and it could help change the way we think about interactions of light in the future. The researchers even suggest that these strips could be used to trap particles. [Science via New Scientist]