Our Next Colloquium

DateThursday, March 31, 2022
Time 11:30 AM
Location McCreary 115, Bowen Auditorium
Speaker Byungchul Cha, Muhlenberg College
Talk Title

Diophantine approximation: how well (or badly) can you approximate an irrational number by rationals?

Talk Abstract

Did you know that 22/7 and 355/113 approximate the number pi astonishingly well? (If you have a calculator with you, try them now!) In this talk, we introduce some basic notions of "Diophantine approximation", a branch of number theory where one is concerned with approximability of irrational numbers by rationals. We will review some old and new results in Diophantine approximation. Contributions made by undergraduate students will be highlighted.


Dr. Cha is a Professor of Mathematics at Muhlenberg College in Allentown, PA.  After teaching at Hendrix College for three years, Dr. Cha came to Muhlenberg College in 2007.  During his Ph.D. program at Johns Hopkins University, he specialized in number theory.  Dr. Cha's research interests include elliptic curves, distribution of zeros of L-functions, and intrinsic Diophantine approximation.  More generally, he is interested in anything related to prime numbers, such as 2, 3, 5, 7, etc.