Events at Physics
Events on Tuesday, October 4th, 2011
- Chaos & Complex Systems Seminar
- Topological chaos
- Time: 12:05 pm
- Place: 4274 Chamberlin
- Speaker: Jean-Luc Thiffeault, UW Department of Mathematics
- Abstract: Topological chaos is a type of chaotic behavior that is `forced' by the motion of obstacles in some domain. I will review two topological approaches, with applications in particular to stirring and mixing in fluid dynamics. The first involves constructing systems such that the fluid motion is topologically complex, usually by imposing a specific motion of rods. I will discuss optimization strategies that can be implemented. The second is diagnostic, where flow characteristics are deduced from observations of periodic or random orbits and their topological properties.
- Theory Seminar (High Energy/Cosmology)
- A global perspective on string inflation
- Time: 4:00 pm
- Place: Chamberlin 5280
- Speaker: Ted van der Aalst, Leiden University
- Abstract: Although inflation is a coarse phenomenon in classical gravity, it is remarkably difficult to describe it in (worldsheet) string theory due to a sensitive dependence on global information of the theory. This sensitivity provides an opportunity to probe stringy phenomena by cosmological observations, but only if the model is fully rooted into string theory. We will discuss some of the requirements for obtaining string inflation both in a supergravity context as well as from a worldsheet perspective. At the worldsheet level, inflation indeed poses coarse but generic conditions on the worldsheet theory, manifesting itself via non-perturbative effects.