Dr. Eric R. Weeks
Samuel Candler Dobbs Professor, Department Chair
|My web pages:|
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|Teaching:||squishy materials, sci. ed. journal club, misc.|
|Pictures:||computer generated, quasicrystals|
|Other:||about me, software, particle tracking, links|
Department of Physics
(use this for US or campus mail)
Mail stop 1131/002/1AB
400 Dowman Dr.
Atlanta GA 30322-2430
|Office:||Math/Science Center N250 (do not use for campus mail)|
|Labs:||347, 350, & 360 Emerson Hall
(404) 712-8669, -8670
Emory University |
Emory College |
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Microscopy of colloidal glasses
Also, as a physicist, I enjoy poking systems to see how they respond. How does a colloidal glass respond when locally perturbed? This sort of question has been asked for theoretical glassy systems; I study this problem using colloids. This may also help shed light on experiments with molecular glasses where perturbations were indirectly studied, but where the microscopic details were unmeasurable.
Nonlinear dynamics, complex fluids, and granular media
Why does mayonnaise act both like a liquid and a solid? What causes shaving cream to flow differently from toothpaste? These types of questions are at the heart of soft condensed matter, the study of materials with both fluid and solid properties (often called "complex fluids"). Moreover, the mechanical properties and ability to flow are in fact the defining features of soft materials, and are key to the practical utility of soft materials. The answers to these questions relate the mesoscopic structure of a complex material to its macroscopic properties (such as its viscoelastic modulus). With the wide variety of mesoscopic structures, it might be expected that the answers would depend strongly on the details of each material, and that the study of such systems would be the study of many special cases. However, recently the analogy of jamming suggests the possibility of universal behavior of complex fluids under stress, and in particular, that such systems may behave like granular media. In each case, the material behaves in many ways like a solid. The analogy of jamming depends on the microscopic behavior of such systems, yet there is little experimental evidence to support the analogy apart from macroscopic similarities between these systems.
Jammed systems are defined as systems with random structures which internally rearrange under imposed stress, so that a subset of the internal structure resists the stress; the formation of these stress-supporting regions is entirely due to the external stress. I plan to use confocal microscopy to examine the structure of complex fluids and granular systems under shear flow, to see if indeed there are microscopic similarities, and to determine if jamming is an appropriate description for any or all of these systems. Moreover, the microscopic dynamics of shear thickening colloids, colloidal glasses, and shear flow of granular systems, are interesting problems in their own right. If the theory of jamming evolves to describe these diverse phenomena, it will be because of a comprehensive and detailed experimental understanding of the microscopic dynamics in each system.
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