SCIENCE - Light knots: Physicists use Maxwell's equations to describe field lines that encode torus knots and links

(Phys.org) —A team of physicists, two from the U.S., and one each from Poland and Spain has used Maxwell's equations to describe field lines that encode all torus knots and links. As they describe in their paper published in the journal Physical Review Letters, the result of using the equations could lead to a method of creating light in the real world that can be tied into knots ...

http://phys.org/news/2013-10-physicists-maxwell-equations-field-lines.