Light Speed

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The Speed of Light, or Light Speed, is the maximum possibble speed in the N-Space universe, and is a constant speed of 299,792.458 km/s (often expressed as 3×108 m/s) in vacuum at which any particle of zero rest-mass (such as the photon) will automatically propagate. This value is commonly abbreviated as "c".

Description (Specifications)

Background: Special Relativity

Mass-Energy Equivalency Principle

According to the mass-energy equivalency principle arising from the Special Theory of Relativity, the energy of any particle may be described by the equation:

  • E = mc2
where:
m = mass
c = speed of light

Thus, any particle has an intrinsic "rest-energy" (E0) as defined by its mass while motionless (its "rest-mass", m0), independent of any internal thermal properties or kinetic energy it may acquire due to motion, as described by the equation:

  • E0 = m0c2.

By extension, an object has a "kinetic mass" (mk) due to its kinetic energy (Ek) while in motion relative to an independent observer that is in addition to its rest mass (m0):

  • Ek = mkc2
or
  • mk = Ek / c2

Thus, as an object accelerates relative to an independent observer, its total mass (mtot) increases:

  • mtot = m0 + mk = (E0 / c2) + (Ek / c2)


The "total energy" (Etot) of a particle is described as the sum of its rest energy (E0) and its kinetic energy (Ek) by the following equation:

  • Etot = E0 + Ek = moc2 / (1 - v2/c2)½


As a consequence, a constant force applied to a particle will produce a continually decreasing acceleration as its mass increases with velocity, implying that in fact F ≠ ma, but rather F ≈ ma for small enough values of velocity. Thus, due to the equivalency principle of mass and energy, as m → with increasing velocity, a → 0, asymptotically approaching a maximum velocity. This limiting velocity is the maximum speed of the universe, and is also the constant speed at which zero-rest mass particles (such as photons and gravitons) propagate, and is colloquially known as the speed of light as a result. It is thus impossible to accelerate an object with non-zero rest mass to the speed of light in a finite amount of time (or alternatively, it would require an infinite force (and/or an infinite amount of energy) to produce the acceleration necessary to accelerate a non-zero rest mass particle to the speed of light).

Lorentz-contraction and Time-dilation

No information currently available.

  • Speed of light constant is the same in all inertial reference frames, independent of observer motion.
  • Time dilation: t = to / (1 - v2/c2)½
  • Lorentz-contraction: l = lo × (1 - v2/c2)½

Light speed as a distance metric

No information currently available.

History & Background (Dossier)

No information currently available.

References & Contributors (Sources)

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