A more serious note in memory of Anatole Katok:
"Entropy measures the unpredictability
of a system that evolves over time."
— Alex Wright, BULLETIN (New Series)
OF THE AMERICAN MATHEMATICAL SOCIETY
Volume 53, Number 1, January 2016, Pages 41–56
http://dx.doi.org/10.1090/bull/1513
Article electronically published on September 8, 2015:
FROM RATIONAL BILLIARDS
TO DYNAMICS ON MODULI SPACES
Abstract:
"This short expository note gives an elementary
introduction to the study of dynamics on certain
moduli spaces and, in particular, the recent
breakthrough result of Eskin, Mirzakhani,
and Mohammadi. We also discuss the context
and applications of this result, and its connections
to other areas of mathematics, such as algebraic
geometry, Teichmüller theory, and ergodic theory
on homogeneous spaces."
See also the lives of Ratner and Mirzakhani.