## The Many Faces of Discreteness: From Granular Crystals and Layered Optical Media to Bose-Einstein Condensates and Beyond

Hey all,

The last talk of the semester will be given this Wednesday from 6-7 in LGRT 1634 by Panos Kevrekidis. Come join us for pizza, soda, and math!
Abstract: We’ll touch on different aspects of discrete systems, as they arise in a variety of recent experiments pertinent to physical applications. We will start from the “traditional” spatial discreteness and how it affects elastic traveling waves in so-called acoustic or granular crystals. We will continue with a form of discreteness (or, more accurately, periodicity) in the evolution variable for pulses passing through a so-called layered optical medium and we will end with an example where the discrete number of components plays a crucial role in the dynamics of two coupled Bose-Einstein
condensates in atomic physics. In each example, we will present the relevant dynamical models and we will attempt to mesh the mathematical analysis and numerical computations with experimental results.

## No Math Club Tonight

Hi all,

Sorry for the late notice. Math Club is cancelled tonight. (4/20)

## How many rabbits will Fibonacci have after 500 years?

This week (4/13) Elizabeth Drellich will give a talk, “Generating Functions: how many rabbits will Fibonacci have after 500 years?” Come join us for pizza and math from 6-7 PM in LGRT 1634!

Abstract: We are all familiar with the Fibonacci sequence, 1,1,2,3,5,8,… It has a very easy formula, each term is the sum of the two previous terms. If I asked for the 100th term in the sequence, you could figure it out in 5 minutes or so. But to find the 1000th or 100000th term might be overly time consuming. Generating functions give us a way to get a simple formula for the nth term of the sequence.

We will look at some simple recurrence relations, including the Fibonacci sequence, and find explicit formulas for their nth terms.

All you need to know about this talk is the definitions of sequences, and power series. If you a currently taking Math 132, you will be able to understand and appreciate this talk. However for all undergrads and most grad students, this should be new and exciting material.

## Malthusian Law and the CIA World Factbook

This week (4/6) Professor Jenia Tevelev will give a talk “Malthusian Law and the CIA World Factbook.” The Malthusian law is a dire prediction that the world’s population will double every 50 years or so. Quite surprisingly, this has very interesting consequences for the statistics of various data accumulated in the CIA World Factbook. Come join us for pizza and math from 6-7 PM in LGRT 1634!