• Corpus ID: 119278376

Why walking is easier than pointing: Hydrodynamics of dry active matter

  title={Why walking is easier than pointing: Hydrodynamics of dry active matter},
  author={John Toner},
  journal={arXiv: Soft Condensed Matter},
  • J. Toner
  • Published 2 December 2018
  • Physics
  • arXiv: Soft Condensed Matter
Although human beings have known about the phenomenon of "flocking"- that is, the coherent movement of large numbers of creatures (flocks of birds, schools of fish, herds of woolly mammoths, etc.)- since prehistoric times, it is only in the last two decades that we have begun to truly understand this phenomenon. In particular, the surprising fact that a very large collection of organisms in two dimensions cannot all {\it point} in the same direction, but can quite easily {\it move} in the same… 

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  • Rev. Lett. 17, 1133 (1966); P. C. Hohenberg, Phys. Rev. 158, 383 (1967); N. D. Mermin, J. Math. Phys. 8, 1061
  • 1967


  • Rev. E 81, 061916
  • 2010


  • Rev. E, 63, 17101
  • 2001

and D

  • Bartolo , Nature Materials 17, 789793
  • 2018


  • Rev. E 77, 046113
  • 2008

This description of the fundamental logic of the hydrodynamic approach, including the lovely phrase "bury your ignorance" that so nicely summarizes it

  • Hydrodynamic Fluctuations, Broken Symmetry, and Correlation Functions
  • 1975

These necessarily have the same RG eigenvalues as those we found here for λ 0 1 , etc. alone, independent of the arbitrary choice of z, χ