Joseph Fourier

lived from 1768 to 1830

Fourier studied the mathematical theory of heat conduction. He established the partial differential equation governing heat diffusion and solved it by using infinite series of trigonometric functions.

Find out more at: http://www-history.mcs.st-andrews.ac.uk/history/Mathematicians/Fourier.html

Some Quotes:

The differential equations of the propagation of heat express the most
general conditions, and reduce the physical questions to problems of
pure analysis, and this is the proper object of theory.
Analytical Theory of Heat, 1822.

Heat, like gravity, penetrates every substance of the universe, its
rays occupy all parts of space. The object of our work is to set forth
the mathematical laws which this element obeys. The theory of heat will
hereafter form one of the most important branches of general physics.
Analytical Theory of Heat, 1822.

The profound study of nature is the most fertile source of mathematical
discoveries.  Quoted in M Kline, Mathematical thought from ancient to
modern times (New York, 1972).