Brownian Motion

  The nineteenth-century Scottish bostanist Robert Brown could merely report on the "Brownian", or erratic, motion of pollen in water, observed under the microscope, he had no explanation for it. Today, its know that the Brownian motion was visible effect of the fact that water is composed of particles, Brown's was the first evidence for atomism - the concept that the universe is composed of indestructible material particles that was an observation rather than deduction.