Which philosopher theorized that all physical objects are made up of atoms?

Democritus is recognized for his groundbreaking theory that all physical objects are composed of indivisible units known as atoms. He proposed that everything in the universe is made up of tiny, unchangeable particles that are in constant motion, a concept that laid the foundational ideas for the field of atomic theory in modern science. Democritus believed that these atoms differed in size, shape, and weight, which determined the properties of the materials they formed. This philosophical perspective marked a significant shift from earlier thoughts about matter, moving from a more elemental-based understanding to a theory of fundamental particles, thereby influencing future scientific inquiry and debate on the nature of matter.