Colloquium Fall 2022

Talks (unless otherwise indicated) are in Davis 301 from 4:00–5:00 PM on Mondays. Refreshments begin at 3:30 PM on the second floor of Davis.

To make sure you get email updates, add yourself to the mathstu (if a student) or mathothers (if not) email groups. Or check the Colby Math Facebook page.

You can see next semester’s schedule.

September 19

Fernando Gouvêa
Colby College
Mr. Euler, you can’t do that!

Title

Abstract

As we all know, in mathematics you have to do things carefully and correctly. But nobody seems to have told Leonhard Euler, the greatest mathematician of the 18th century, certain things that all calculus students know. This talk is about Euler doing the wrong things and still getting the right answer. Everything in the talk is about infinite series and figuring out what their sums are, so if you know about series and convergence you’ll enjoy following Euler’s steps.

 

October 24

Stephanie Dobson
Colby College
Animal communication enables collective migration in a dynamic ocean

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Abstract

Blue whales (Balaenoptera musculus) in the eastern North Pacific ocean migrate annually between southern breeding and northern foraging, yet the precise mechanics and cues of migration remain unknown. The population is known to communicate with a variety of call types over distances of hundreds of kilometers. Empirical evidence from hydrophones proposes that these calls are a main driver of the breeding migration, but it is believed that environmental cues and events, social communications, and breeding patterns all factor into migration decisions. Here, we utilize an individual-based model to examine the role of long-range social communication in driving the timings of the collective migrations. We measure and compare population-level outcomes of migration decisions based on combinations of individual foraging behaviors, prey intake, and social communications against a yearday-driven migration mechanism and a null (non-migratory) model. Our results help extract the important role of social communication in blue whale migrations and find that social communications are necessary to reproduce realistic and observed migration patterns. Moreover, the socially informed strategies enable flexible migration timings that maximize prey intake in dynamic conditions and anomalous years.

 

October 31 Diamond 122

Leo Livshits
Colby College
“What Is … ?” Colloquium:  Lengthy Adventures

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Abstract

I was once told to imagine “unbending a curve without stretching it”. My mind’s eye produced images of a thin piece of wire being unbent, and of wire molecules being rearranged in the process. “Isn’t the outer length of a semi-circular wire longer than the inner length?” teased the Devil’s advocate. “Think of a bend in a road; isn’t this why we use the differential in cars?”

I tried to quiet the little Devil by imagining thinner and thinner wires, and was gaining an upper hand until the pesky objector noted that “at some point you have to go so sub-atomic that there is no discernible wire to speak of.”  But if I abandon the idea of “unbending without stretching”, how exactly do I make sense of a length of a curve? When the inner voice piped in with “… and what is a curve, anyway?”, I decided it was time to get serious about the issue.

In this “What is … ?” colloquium aimed at students, we will discuss common and less common notions of length for a curve in multiple dimensions and go on a brisk jaunt through some subtle but fundamental ideas of Analysis. The talk will serve as a shameless advertisement of the value of MA338 & MA439 to one’s intellectual development and peace of mind.

 

November 7 (Runnals Dinner Guest Speaker) Olin 001

Talea Mayo
Emory University
Climate Change Impacts on Hurricane Storm Surge Risk

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Abstract

 

November 28 Diamond 122

Changningphaabi Namoijam
Colby College
Number Theory and Function Fields

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Abstract

In classical number theory, we study integers and objects related to integers. We can consider polynomials as analogues of integers because there are many results in the world of polynomials that complement ones from the classical case. For example, there is an analogue of the irrational number π. In this talk, we will explore this analogous π and some other number theoretic results relating to polynomials.