06/09/2026
“What is the world made of?” Today we say atoms, and that’s thanks in part to John Dalton. He was the first to put forward experimental evidence of elements and matter being composed of extremely small particles, which he called atoms.
Born on this day exactly 255 years ago, Dalton is renowned for his pioneering work in physics and chemistry. Dalton theorized that every form of matter — solid, liquid or gas — was composed of indivisible and indestructible building block, or atoms. He proposed that all atoms of an element were identical, but that different elements had atoms of differing size, mass and chemical properties. This was the first complete attempt to describe all matter in terms of atoms and their properties.
Although advances in science and technology have proven this theory was not exactly correct, it did lay the foundation for how we now understand matter at an atomic and sub-atomic level.
