Colloquium

The rapidly expanding thickening universe: critical points, dethickening, superthickening, and meta material liquids

Speaker: Itai Cohen (Cornell University, Ithaca, NY)

Date and time

Abstract

Each year, millions of viewers head to YouTube to watch people walk on water. Of course, these people are not actually walking on water: as stress is applied to a suspension of cornstarch in water, the cornstarch particles come close enough to form force chains that are capable of supporting the weight of a person. While these principles help create popular videos, they can be problematic when it comes to efficient processing of industrial suspensions, which in turn has motivated many studies into this fascinating behavior. In this talk I will review what we understand about thickening, discuss universal features of the thickening transition, show how thickening can be tuned by rapid oscillation protocols to breakup or reinforce the force chains, and describe how we are starting to think of using these techniques to create metamaterial liquids whose viscosity arises from the combination of thickened and Newtonian flows. 

Itai Cohen

Short Biography
Professor Itai Cohen studies the physics of matter in motion. At Cornell, his research has focused on building robots the size of cells, controlling the shear thickening behavior of microscopic and nanoscopic particles suspended in a fluid, exploring the mechanics of materials ranging from biological tissues to origami inspired metamaterials, discovering the aerodynamic and neuromuscular mechanisms used by insects during flapping flight, and determining how audiences at heavy metal concerts coordinate their movement. Understanding how emergent behaviors arise from the microscopic rules governing these systems remains one of the biggest challenges in Physics.
Professor Cohen received his BS in Physics from the University of California at Los Angeles, and his PhD in Physics from the University of Chicago. Following his graduate studies, he was a Post-doctoral fellow in Physics and the Division of Engineering and Applied Science at Harvard University. In 2005 he joined Cornell and is currently a professor of Physics. Professor Cohen is an NSF Career grant recipient, he is a Fellow of the American Physical Society, and has served as a Feinberg and Braginsky fellow at the Weizmann Institute. He is slated to be the Rosi and Max Varon Visiting Professor at the Weizmann Institute (2021), and the van der Waals Visiting Professor at the University of Amsterdam (2022).