2006/12/31 by Vijay Narayan, Sriram Ramaswamy, Narayanan Menon · 1 citation
Physics and Astronomy · #cond-mat.soft #cond-mat.stat-mech
paper · pdf · doi:10.1126/science.1140414
published as Science 317, 105 (2007) · This is the author's version of the work. It is posted here by permission of the AAAS. The definitive version is to appear in SCIENCE
arxiv created 2007/06/14 · arxiv updated 2011/11/09
Coherently moving flocks of birds, beasts or bacteria are examples of living matter with spontaneous orientational order. How do these systems differ from thermal equilibrium systems with such liquid-crystalline order? Working with a fluidized monolayer of macroscopic rods in the nematic liquid crystalline phase, we find giant number fluctuations consistent with a standard deviation growing linearly with the mean, in contrast to any situation where the Central Limit Theorem applies. These fluctuations are long-lived, decaying only as a logarithmic function of time. This shows that flocking, coherent motion and large-scale inhomogeneity can appear in a system in which particles do not communicate except by contact.