Charles-Édouard Guillaume

Charles-Édouard Guillaume was a Swiss physicist whose research on nickel–steel alloys led to Invar and Elinvar, materials notable for their unusually stable dimensions and elastic properties. He received the 1920 Nobel Prize in Physics.

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Nobel Prize in Physics: An annual international award recognizing outstanding contributions to physics. The 1920 prize recognized Guillaume’s discovery of anomalies in nickel–steel alloys.
Thermal expansion: The change in a material’s dimensions as its temperature changes. Invar’s defining anomaly is its exceptionally low thermal expansion over a useful temperature range.
Pendulum clock: A clock that measures time through the regular oscillation of a pendulum. Invar rods reduce temperature-driven changes in pendulum length and clock rate.
Nickel–iron alloy: A metallic material composed primarily of nickel and iron, often with other elements added. Guillaume mapped how nickel content altered the expansion of iron-based alloys.
Pierre Weiss: A French physicist known for foundational work on magnetism and ferromagnetism. Weiss’s magnetic research provides a scientific counterpart to Guillaume’s study of nickel alloys.
Invar: A nickel–iron alloy with unusually low thermal expansion near room temperature. Guillaume identified and developed this alloy after finding anomalous expansion in nickel–steel compositions.
Precision measurement: Measurement designed to minimize uncertainty and control systematic error. Guillaume’s work connected stable alloy dimensions with the reliability of reference instruments.
International Prototype of the Metre: The platinum–iridium bar that served as the international definition of the metre from 1889 to 1960. Guillaume’s metrology career centered on maintaining precision standards such as this prototype.
Albert Einstein: A theoretical physicist who developed the theories of special and general relativity. Einstein shared the 1920 Nobel Prize announcement with Guillaume, though for an earlier award year.
Elinvar: A nickel–iron–chromium alloy whose elastic modulus changes little with temperature. This alloy extends Guillaume’s work from dimensional stability to temperature-stable elasticity.