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speed of light
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relativistic velocity combination
invariance of the speed of light length contraction and time dilation Figure 6: Fizeau's method for measuring the velocity of light. Figure 7: Michelson's Mount Wilson experiment, 1927.
Understand refraction and why the speed of light changes when it travels through glass
relativistic mass
What would traveling at light speed really look like?
See how to break the “cosmic speed limit” of light by using a laser
Quizzes
Italian physicist Guglielmo Marconi at work in the wireless room of his yacht Electra, c. 1920.
All About Physics Quiz
Read Next
July, 2006, Launch of Space Shuttle Discovery STS-121. See attached for full caption information.
Will Light-Speed Space Travel Ever Be Possible?
Highway Night Traffic Portland, drive, driving, car, automobile.
What's the Difference Between Speed and Velocity?
Galaxy clusters like Abell 2744 can act as a natural cosmic lens, magnifying light from more distant, background objects through gravity. NASA's James Webb Space Telescope may be able to detect light from the first stars in the universe if they are gravitationally lensed by such clusters. (astronomy, space exploration, galaxies)
How Fast Is the Universe Expanding?
Albert Einstein.
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Planet Jupiter with its moon Io at left, photographed by the Cassini orbiter during the Cassini-Huygens mission, 2000. spacecraft
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Russian grand duchess Anastasia; undated photograph. (Anastasiya Nikolayevna, Tsar Nicholas II)
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William Shakespeare
The Death of Shakespeare
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Figure 13: A Maxim machine gun, belt-fed and water-cooled, operated by German infantrymen, World War I.
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speed of light: Facts & Related Content

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Facts

Also Known As electromagnetic constant • c • velocity of light

Photos and Videos

invariance of the speed of light
length contraction and time dilation
Figure 6: Fizeau's method for measuring the velocity of light.
Figure 7: Michelson's Mount Wilson experiment, 1927.
relativistic velocity combination
Understand refraction and why the speed of light changes when it travels through glass
relativistic mass
What would traveling at light speed really look like?
See how to break the “cosmic speed limit” of light by using a laser
See All Videos and Images →

Related Topics and References

Topics
Dig Deeper: More Articles That Discuss This Topic

Key People

A.A. Michelson.
A.A. Michelson
German-born American physicist
James Bradley, detail of an oil painting after Thomas Hudson, c. 1742-47; in the National Portrait Gallery, London
James Bradley
English astronomer
Harlow Shapley
American astronomer
Lene Hau
Danish scientist
Louis Essen
British physicist
Ole Rømer
Ole Rømer
Danish astronomer
Foucault, Léon
Léon Foucault
French physicist
Armand-Hippolyte-Louis Fizeau.
Armand-Hippolyte-Louis Fizeau
French physicist

Related Quizzes and Features

Quiz
Italian physicist Guglielmo Marconi at work in the wireless room of his yacht Electra, c. 1920.
All About Physics Quiz
Demystified
July, 2006, Launch of Space Shuttle Discovery STS-121. See attached for full caption information.
Will Light-Speed Space Travel Ever Be Possible?
Highway Night Traffic Portland, drive, driving, car, automobile.
What's the Difference Between Speed and Velocity?