Nodal sets of random spherical harmonics

Mikhail Sodin
Tel Aviv University
February 17, 2017
Abstract: In the talk I will describe what is known and (mostly) unknown about asymptotic statistical topology and geometry of zero sets of random spherical harmonics of large degree. I plan to discuss (a) several provoking open questions and (b) the first non-trivial lower bound recently obtained with Fedor Nazarov (work in progress) for the variance of the number of connected components of the zero set.

Log lower bound on the number of nodal domains on some surfaces of negative curvature

Steven Zelditch
Northwestern University
February 17, 2017
Abstract: An open problem is to prove that for any (or at least any generic) Riemannian metric, there is some sequence of eigenfunctions of the Laplacian for which the number of nodal domains tends to infinity. It sounds easy but as yet there are almost no examples of such metrics except for separation of variables situations, and the results of Ghosh-Reznikov-Sarnak and of Junehyuk Jung and myself. This talk is about a quantitative improvement in which we give a log lower bound for the number of nodal domains for negatively curved `real Riemann surfaces'.

Equidistribution of random waves on shrinking balls

Melissa Tacy
Australian National University
February 17, 2017
Abstract: In the 1970s Berry conjectured that the behavior of high energy, quantum-chaotic billiard systems could be well modeled by random waves. That is random combinations of the plane waves e^{ik ·x}. On manifolds it is more natural to randomize over the eigenfunctions of the Laplace-Beltrami operator. In this talk I will present results showing that such random waves equidistribute on balls that shrink with the eigenvalue. This is joint work with Xiaolong Han.

$C^\infty$ closing lemma for three-dimensional Reeb flows via embedded contact homology

Kei Irie
Kyoto University
February 16, 2017
$C^r$ closing lemma is an important statement in the theory of dynamical systems, which implies that for a $C^r$ generic system the union of periodic orbits is dense in the nonwondering domain. $C^1$ closing lemma is proved in many classes of dynamical systems, however $C^r$ closing lemma with $r > 1$ is proved only for few cases. In this talk, I'll prove $C^\infty$ closing lemma for Reeb flows on closed contact three-manifolds. The proof uses recent developments in quantitative aspects of embedded contact homology (ECH).

Post Concert Discussion

Gamelan Galak Tika and David Lang
February 10, 2017
Edward T. Cone Concert Series: February 10, 2017

A concert of new and traditional Balinese music will be performed by Boston’s large percussion orchestra, Gamelan Galak Tika. An ensemble comprised of gongs, metallophones and hand drums, cymbals, vocals, bamboo flutes and spiked fiddles, Gamelan Galak Tika is approximately thirty members strong, drawing membership from the Massachusetts Institute of Technology students, staff and community. A concert talk with David Lang and the artists will follow the Friday, February 10 performance.