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Birth, Death, and Flight: A Theory of Malthusian Flock

Event Details

Event Dates: 

Thursday, December 13, 2012 - 5:00am

Speaker Name(s): 

John Toner

Speaker Affiliation(s): 

University of Oregon
Seminar Type/Subject

Event Details & Abstract: 

I study “Malthusian Flocks”: moving aggregates of self-propelled entities (e.g., organisms, cytoskeletal actin, microtubules in mitotic spindles) that reproduce and die. Long-ranged order (i.e., the existence of  a non-zero average velocity) is possible in thesesystems, even in  spatial dimension d=2. Their spatiotemporal scaling structure can be determined exactly in d=2;  furthermore, they  lack both the longitudinal sound waves and the giant number fluctuations found in immortal flocks. Number fluctuations are very persistent,  however,  and propagate along the direction of flock motion, but at a different speed.