Maxwell formulates the theory of electromagnetism
- Date
- 1865–1873
- Category
- Science, technology & invention
- Region
- Britain (Cambridge / London)
- Era
- Modern
- Significance
The Scottish physicist James Clerk Maxwell unified electricity, magnetism, and light into a single mathematical theory.
In his 1865 paper 'A Dynamical Theory of the Electromagnetic Field' he expressed the behaviour of electric and magnetic fields in a set of equations and introduced the concept of displacement current, leading to the prediction that oscillating fields propagate as waves travelling at the speed of light. He inferred that light itself is an electromagnetic wave. Maxwell consolidated and extended this work in his two-volume Treatise on Electricity and Magnetism (1873), giving the most complete contemporary account of the field. His equations, later cast into their familiar compact form by Oliver Heaviside and Heinrich Hertz, predicted electromagnetic waves beyond the visible spectrum; Hertz experimentally generated and detected radio waves in 1887, confirming the theory. Maxwell's synthesis ranks among the greatest achievements of theoretical physics, providing the foundation for radio, radar, and modern telecommunications and helping to set the stage for relativity and quantum theory in the twentieth century.
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Empires active in 1865–1873
- French Colonial Empire (Second)1830 CE – 1962 CE
- Russian Empire1721 CE – 1917 CE
- British Empire1583 CE – 1997 CE
- Qing Dynasty1636 CE – 1912 CE
- Spanish Empire1492 CE – 1976 CE
- Portuguese Empire1415 CE – 1999 CE
Related science, technology & invention events
- Opening of the Suez Canal17 November 1869
- Darwin publishes On the Origin of Species24 November 1859
- Third Plague Pandemic begins in Yunnan1855 (origin in Yunnan); global spread from 1894
- Bell Patents the Telephone1876
- Edison's Electric Light and Central Power1879 (Pearl Street 1882)
- Germ Theory of Disease Established by Pasteur and Koch1882 (Koch's tuberculosis bacillus, 24 March)
Further reading
The wider story
A Little History of Science
Warm, jargon-free tour of discovery from Babylonian stargazers to the genome.
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