Wilson, Charles Thomson Rees (1869-1959) was a British physicist who won the 1927 Nobel Prize in physics for his 1912 invention of the cloud chamber. The Wilson cloud chamber was a device that made the paths of electrically charged subatomic particles visible, allowing scientists to study these particles.

Wilson was born on Feb. 14, 1869, in a town near Glencorse, Scotland, to John Wilson, a sheep farmer, and Annie Clark Harper. He studied science and received his bachelor's degree in 1887 from Owens College in Manchester, England. He received a degree in physics from Sidney Sussex College in Cambridge, England, in 1892. From 1894 to 1896, he conducted research at the Cavendish Laboratory under the direction of British physicist Sir Joseph John Thomson, whose research led to the discovery of the electron.

Fascination with such meteorological phenomena as halos produced by sunlight on mist stimulated Wilson's greatest work. Intending to reproduce such optical phenomena in a laboratory setting, Wilson used a device called an expansion chamber that produced fog and rain. Through repeated efforts, he created a vapor in an atmosphere free of dust particles. This indicated to him that water droplets form by condensing around ions (atoms that have an electric charge) rather than dust particles, as commonly believed among scientists at that time. Wilson's discovery strongly supported the existence of ions, atoms, and molecules.

Using the cloud chamber, Wilson could photograph atomic particles made visible by means of water droplets condensed on the ions produced along their paths. This remarkable discovery gave scientists visual evidence that these particles existed beyond theory. Today, devices called tracking chambers, sampling calorimeters, and scintillators have replaced Wilson cloud chambers.

Focusing on atmospheric electricity, Wilson went on to create a new form of electroscope, with which he was able to measure the electric field in the atmosphere with 100 times greater sensitivity than any prior device.

He died on Nov. 15, 1959, in Carlops, Scotland.