Knots of light
Light may seem to travel a straight line, but sometimes it gets twisted into knots. In January 2010 researchers reported using a computer-controlled hologram to twist beams of laser light into pretzel shapes. The holograms, which direct the flow of light, were specially created to send light in certain directions and shapes.
The researchers used a field of mathematics known as knot theory to study the resulting loops. These swirls of light, called optical vortices, could have implications for future laser devices, the physicists said.