Beams of light can, in theory, be tied into three-dimensional knots that hold their shape.
Hridesh Kedia at the University of Chicago in Illinois and colleagues found solutions to equations that govern classical electromagnetism and thus light — the visible frequencies of electromagnetic radiation.
The solutions yield trefoil knots with three loops, cinquefoil knots with five loops (pictured) and other types of torus knot. Whereas previous approaches produced only ephemeral structures, the new knots remain stable because their electric and magnetic field lines are always at right angles to each other and of equal strength. This gives rise to strands that, like rubber bands, stretch and deform but keep their shape.
Focused laser beams could potentially create such knots, which might be used for moulding plasma and other types of matter, the researchers suggest.
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Tying knots with light beams. Nature 502, 413 (2013). https://doi.org/10.1038/502413d
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DOI: https://doi.org/10.1038/502413d
