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  2. Foucault's measurements of the speed of light - Wikipedia

    en.wikipedia.org/wiki/Foucault's_measurements_of...

    In 1850, Léon Foucault measured the relative speeds of light in air and water. The experiment was proposed by Arago, who wrote, Two radiating points placed one near the other and on the same vertical, shine instantly in front of a rotating mirror. The rays from the upper point reach this mirror only by passing through a tube filled with water ...

  3. Speed of light - Wikipedia

    en.wikipedia.org/wiki/Speed_of_Light

    v. t. e. The speed of light in vacuum, commonly denoted c, is a universal physical constant that is exactly equal to 299,792,458 metres per second (approximately 300,000 kilometres per second; 186,000 miles per second; 671 million miles per hour).

  4. Michelson–Morley experiment - Wikipedia

    en.wikipedia.org/wiki/Michelson–Morley_experiment

    They set a limit on the anisotropy of the speed of light resulting from the Earth's motions of Δc/c ≈ 10 −15, where Δc is the difference between the speed of light in the x- and y-directions. [33] As of 2015, optical and microwave resonator experiments have improved this limit to Δc/c ≈ 10 −18.

  5. Photon - Wikipedia

    en.wikipedia.org/wiki/Photon

    A photon (from Ancient Greek φῶς, φωτός (phôs, phōtós) 'light') is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless particles that always move at the speed of light ...

  6. Corpuscular theory of light - Wikipedia

    en.wikipedia.org/wiki/Corpuscular_theory_of_light

    The fact that light could be polarized was for the first time qualitatively explained by Newton using the particle theory. Étienne-Louis Malus in 1810 created a mathematical particle theory of polarization. Jean-Baptiste Biot in 1812 showed that this theory explained all known phenomena of light polarization. At that time polarization was ...

  7. 2011 OPERA faster-than-light neutrino anomaly - Wikipedia

    en.wikipedia.org/wiki/2011_OPERA_faster-than...

    End results. On July 12, 2012, the OPERA collaboration published the end results of their measurements between 2009 and 2011. The difference between the measured and expected arrival time of neutrinos (compared to the speed of light) was approximately 6.5 ± 15 ns. This is consistent with no difference at all, thus the speed of neutrinos is ...

  8. Aberration (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Aberration_(astronomy)

    In 1727, James Bradley provided a classical explanation for it in terms of the finite speed of light relative to the motion of the Earth in its orbit around the Sun, [3] [4] which he used to make one of the earliest measurements of the speed of light. However, Bradley's theory was incompatible with 19th-century theories of light, and aberration ...

  9. Treatise on Light - Wikipedia

    en.wikipedia.org/wiki/Treatise_on_Light

    Optics. Published. 1690. Treatise on Light: In Which Are Explained the Causes of That Which Occurs in Reflection & Refraction (French: Traité de la Lumière: Où sont expliquées les causes de ce qui luy arrive dans la reflexion & dans la refraction) is a book written by Dutch polymath Christiaan Huygens that was published in French in 1690.