The influential physicist known for his contributions to quantum mechanics and the uncertainty principle is Werner Heisenberg. His principle asserts that certain pairs of physical properties, like position and momentum, cannot both be precisely measured simultaneously. This groundbreaking idea fundamentally changed our understanding of subatomic particles and laid the groundwork for the development of modern physics. Heisenberg's work had far-reaching implications, influencing various fields and leading to a deeper comprehension of the nature of reality at quantum levels.