Long-lived giant number fluctuations in a swarming granular nematic
Long-lived giant number fluctuations in a swarming granular nematic
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DOI：
10.1126/science.1140414
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发表时间：
2007-07-06
期刊：
影响因子：
56.9
通讯作者：
Menon, Narayanan
中科院分区：
文献类型：
--
作者：
Narayan, Vijay;Ramaswamy, Sriram;Menon, Narayanan
连贯移动的鸟群、野兽群或细菌群是具有自发定向秩序的生命物质的例子。这些系统与具有这种液晶顺序的热平衡系统有何不同？工作与流化单层的宏观棒在液晶相，我们发现巨大的数字波动与标准偏差线性增长的平均值相一致，在任何情况下，中心极限定理适用。这些波动是长期存在的，只作为时间的对数函数衰减。这表明，群集、相干运动和大尺度不均匀性可以出现在一个系统中，在这个系统中，粒子除了接触之外不进行通信。
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.