Modern physics, math, engineering would be unthinkable without the former: the fundamental method of dealing with infinitesimal numbers. Leibniz was the first to publish it. He developed it around 1673. In 1679, he perfected the notation for integration and differentiation that everyone is still using today.
The principles of binary computers based on the dual system he published in 1679. This became the basis of virtually all modern machines.
The first non- programmable computer, however, was due to Schickard (1623). Compare the computer history speedup page.
See also:
J. Schmidhuber (AI Blog, 2021). 375th birthday of Leibniz, founder of computer science.
J. Schmidhuber (2021). Der erste Informatiker. Wie Gottfried Wilhelm Leibniz den Computer erdachte. (The first computer scientist. How Gottfried Wilhelm Leibniz conceived the computer.) Frankfurter Allgemeine Zeitung (FAZ), 17/5/2021. FAZ online: 19/5/2021.
J. Schmidhuber (AI Blog, 2021). 375. Geburtstag des Herrn Leibniz, dem Vater der Informatik.