is: the microscopic random motion of pollen grains and other small particles suspended in gases or liquids. [P7.1, P8.1]
was first observed: by the botanist Robert Brown (1773-1858). [P7.1, P8.1]
was explained: as the result of numerous unseen molecular collisions, by Albert Einstein (1879-1955) in 1905. [P7.1, P8.1]
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