M. C. Escher sketched them in pencil, now scientists are creating them out of photons.
Möbius strips are a three-dimensional shapes with only one surface. It’s not hard to make one yourself: take a strip of paper, twist it once, and tape the ends together. The result is something with length, width, and depth—but only one surface. In other words, you’ll never have to lift your finger to trace both sides of the strip you originally cut.
Real, unmanufactured Möbius strips rarely occur spontaneously in nature. That’s why they’re also commonly called impossible shapes. But now, scientists have rendered one out of light.
Light is a transverse electromagnetic wave, meaning that its oscillations move perpendicular to the direction in which its energy travels. Polarizing light confines it to certain planes depending how its electromagnetic wave or waves are oriented in space. One way to produce polarized light is to use lasers.
In 2005, physicist Isaac Freund of Israel’s Bar-Ilan University proposed the idea that light’s polarization could actually become “twisted.” Ten years later, a team led by Peter Banzer of the Max Planck Institute for the Science of Light in Erlangen, Germany has tested Freund’s hypothesis using two circularly polarized waves that intersect at a small angle with respect to each other.
Here’s Katherine Kornei, writing for New Scientist:
In 2010, Freund proposed a way to test this : prepare two polarised beams of light and allow them to interfere with each other in a particular way. The interference will cause the polarisation to twist, forming a Möbius strip.
Banzer’s team scattered two polarised green laser beams off a gold bead [a liquid crystal device called a q-plate] that was smaller than the wavelength of the light. The resulting inference introduced a polarisation pattern with either three or five twists, giving it a Möbius-like structure.
This experiment shows that, with a nudge from scientists, light in certain situations can manifest Möbius strips. The discovery could advance certain biomedical techniques (like the burgeoning field of optogenetics) that rely on an understanding of how complex light beams interact with matter.
Photo Credit: gfpeck / Flickr (CC BY-NC-ND 2.0)pl6m89th