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Long-Lived Giant Number Fluctuations in a Swarming Granular Nematic

2007; American Association for the Advancement of Science; Volume: 317; Issue: 5834 Linguagem: Inglês

10.1126/science.1140414

1095-9203

Vijay Narayan, Sriraṁ Ramaswamy, Narayanan Menon,

Ecosystem dynamics and resilience

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.