Page "Friedrich Bessel" Paragraph 7

In the second decade of the 19th century while studying the dynamics of ' many-body ' gravitational systems, Bessel developed what are now known as Bessel functions.

Critical for the solution of certain differential equations, these functions are used throughout both classical and quantum physics.

Even in the absence of any work in astronomy, Bessel's role in developing the functions which now bear his name would have, by itself, placed him among the most significant and influential mathematicians of the 19th century.