# Atmospheric Sciences

### What Is Randomness?

Anastasios Tsonis, Professor

Course: ATM SCI 194, SEM 001
Class Number: 53485
Credits: 3 NS
Time: TR 9:30 – 10:45 AM
Place: EMS E424A

### Course Description:

This unique course explores the definition, sources and role of randomness. A joyful discussion with many non-mathematical and mathematical examples leads to the identification of three sources of randomness: randomness due to irreversibility which inhibits us from extracting whatever rules may underlie a process, randomness due to our inability to have infinite power (chaos), and randomness due to many interacting systems. Here, all sources are found to have something in common: infinity. The discussion then moves to the physical system (our universe).Through the quantum mechanical character of small scales, the second law of thermodynamics and chaos, randomness is shown to be an intrinsic property of nature - this is consistent with the three sources of randomness identified above. Finally, an explanation is given as to why rules and randomness cannot exist by themselves, but instead have to coexist. Many examples are presented, ranging from pure mathematical to natural and social processes, that clearly demonstrate how the combination of rules and randomness produces the world we live in.

The course and the textbook are tailored for people who have finished high school math.

### About the Instructor:

Anastasios Tsonis has a background in Physics and Mathematics and a Ph.D in Atmospheric Sciences. He has published 115 peer reviewed papers and six books. He was one of the first scientists to promote the application of Chaos theory and nonlinear data analysis in Atmospheric Sciences. He and his post-doctoral fellow Jim Elsner in a series of papers in the late 1980s popularized and introduced this theory to meteorologists. Their research has led to the Tsonis criterion, to a method bearing their names, and to a statistical test also bearing their names. The Tsonis Criterion refers to the necessary number of points required in attractor reconstructions. The Tsonis-Elsner method is a method used to distinguish low-dimensional chaos from random fractal processes. The Elsner-Tsonis test is a statistical test designed to assess the significance of climate oscillations. In addition, they have introduced the notion of connected subsystems in the climate system. In 2004 Tsonis was the first scientist in the world to apply the new concepts of ‘small-world’ networks to atmospheric sciences. By now there are special sessions on climate networks in both AGU and EGU general assemblies, as well as individual workshops solely dedicated to this subject. His research in this area has led to the discovery of a new dynamical mechanism for major climate shifts. This mechanism explains all major global temperature shifts in the 20th century. Tsonis has also done significant research in the area of global change, where he have developed and published a theory about the relationship of global temperature and the frequency of El Nino.