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  2. Light - Wikipedia

    en.wikipedia.org/wiki/Light

    This should not be confused with the Nichols radiometer, in which the (slight) motion caused by torque (though not enough for full rotation against friction) is directly caused by light pressure. [28] As a consequence of light pressure, Einstein in 1909 predicted the existence of "radiation friction" which would oppose the movement of matter. [29]

  3. List of states of matter - Wikipedia

    en.wikipedia.org/wiki/List_of_states_of_matter

    Strange matter: A type of quark matter that may exist inside some neutron stars close to the Tolman–Oppenheimer–Volkoff limit (approximately 2–3 solar masses). May be stable at lower energy states once formed. Quark matter: Hypothetical phases of matter whose degrees of freedom include quarks and gluons Color-glass condensate

  4. Speed of light - Wikipedia

    en.wikipedia.org/wiki/Speed_of_Light

    For example, for visible light, the refractive index of glass is typically around 1.5, meaning that light in glass travels at ⁠ c / 1.5 ⁠ ≈ 200 000 km/s (124 000 mi/s); the refractive index of air for visible light is about 1.0003, so the speed of light in air is about 90 km/s (56 mi/s) slower than c.

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

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

    The light reflected back from the spherical mirrors is diverted by beam splitter g towards an eyepiece O. If mirror m is stationary, both images of the slit reflected by M and M' reform at position α. If mirror m is rapidly rotating, light reflected from M forms an image of the slit at α' while light reflected from M' forms an image of the ...

  6. Radiation - Wikipedia

    en.wikipedia.org/wiki/Radiation

    Light, or visible light, is a very narrow range of electromagnetic radiation of a wavelength that is visible to the human eye, or 380–750 nm which equates to a frequency range of 790 to 400 THz respectively. [4] More broadly, physicists use the term "light" to mean electromagnetic radiation of all wavelengths, whether visible or not.

  7. Refractive index - Wikipedia

    en.wikipedia.org/wiki/Refractive_index

    A ray of light being refracted through a glass slab Refraction of a light ray. In optics, the refractive index (or refraction index) of an optical medium is the ratio of the apparent speed of light in the air or vacuum to the speed in the medium. The refractive index determines how much the path of light is bent, or refracted, when entering a ...

  8. Matter wave - Wikipedia

    en.wikipedia.org/wiki/Matter_wave

    The concept that matter behaves like a wave was proposed by French physicist Louis de Broglie (/ d ə ˈ b r ɔɪ /) in 1924, and so matter waves are also known as de Broglie waves. The de Broglie wavelength is the wavelength , λ , associated with a particle with momentum p through the Planck constant , h : λ = h p . {\displaystyle \lambda ...

  9. Postulates of special relativity - Wikipedia

    en.wikipedia.org/wiki/Postulates_of_special...

    1. First postulate (principle of relativity) The laws of physics take the same form in all inertial frames of reference.. 2. Second postulate (invariance of c) . As measured in any inertial frame of reference, light is always propagated in empty space with a definite velocity c that is independent of the state of motion of the emitting body.