<< Waves surround us all the time: sound waves in the noise around us, light waves enabling us to see, and according to quantum mechanics, all matter has a wave nature. Most of these waves, however, do not resemble the regular train of waves at the shore of the ocean—the pattern is much more chaotic. Most significantly, the whirls and eddies form lines in space called vortices. Along these lines, the wave intensity is zero, and natural wave fields - light, sound and quantum matter - are filled with a dense tangle of these null filaments >>
Knots in chaotic waves. July 29, 2016.
http://m.phys.org/news/2016-07-chaotic.html
Alexander J. Taylor & Mark R. Dennis. Vortex knots in tangled quantum eigenfunctions. Nature Communications. Published 29 Jul 2016 DOI: 10.1038/ncomms12346 OPEN
http://www.nature.com/ncomms/2016/160729/ncomms12346/full/ncomms12346.html