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Superfluid transport of information in turning flocks of Starlings
Associate Professor, Department of Physics
University of Rome, La Sapienza
Collective decision-making in biological systems requires all individuals in the group to go through a behavioral change of state. During this transition, the efficiency of information transport is a key factor to prevent cohesion loss and preserve robustness. The precise mechanism by which natural groups achieve such efficiency, though, is currently not fully understood. In this talk, I will present an experimental study of starling flocks performing collective turns in the field. We find that the information to change direction propagates across the flock linearly in time with negligible attenuation, hence keeping group decoherence to a minimum. This result contrasts with current theories of collective motion, which predict a slower and dissipative transport of directional information. To explain the experimental results we propose a new model of collective motion. Its key ingredient is the presence of a conservation law, generated by the rotational symmetry of the system, which naturally leads to a linear dispersion relation as the one observed in natural flocks. The theory belongs to the same universality class as superfluid transport, and also provides a quantitative expression for the speed of propagation of the information, according to which transport must be swifter the stronger the group's orientational order. This prediction is verified by the data. Biography
Irene Giardina received a Ph.D. degree in theoretical physics from the University of Rome La Sapienza in 1998. From 1999 to 2001 she worked as post-doctoral fellow at the University of Oxford and at the Laboratoire de Physique Theorique, CEA Saclay, where she studied a variety of problems in disordered and complex systems. In 2001 she was appointed research scientist at the Institute for Complex Systems, of the National Research Council in Rome. Together with Andrea Cavagna, she set up a new lab dedicated to apply methods from statistical physics to study collective behavior in animal groups and biological systems. From 2013 she is Associate Professor at the Department of Physics, University of Rome La Sapienza, and she is currently Visiting Professor at the Initiative for the Theoretical Sciences, Graduate Center, City University of New York.
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