The variable speed of light (VSL) concept states that the speed of light in a vacuum, usually denoted by c, may not be constant in most cases. In most situations in condensed matter physics when light is traveling through a medium, it effectively has a slower speed. Virtual photons in some calculations in quantum field theory may also travel at a different speed for short distances; however, this doesn't imply that anything can travel faster than light. While it is usually thought that no meaning can be ascribed to a dimensional quantity such as the speed of light varying in time (as opposed to a dimensionless number such as the fine structure constant), in some controversial theories in cosmology, the speed of light also varies by changing the postulates of special relativity. However, this would require a rewrite of much of modern physics to replace the current system which depends on a constant c.
Read more about Variable Speed Of Light: Varying c in Classical Physics, Varying c in Quantum Theory, Varying c in Time, The Varying Speed of Light Cosmology
Famous quotes containing the words speed of light, variable, speed and/or light:
“For myself and my loved ones, I want the heat, which comes at the speed of light. I don’t want to have to hang about for the blast, which idles along at the speed of sound.”
—Martin Amis (b. 1949)
“Walked forth to ease my pain
Along the shore of silver streaming Thames,
Whose rutty bank, the which his river hems,
Was painted all with variable flowers,”
—Edmund Spenser (1552?–1599)
“For myself and my loved ones, I want the heat, which comes at the speed of light. I don’t want to have to hang about for the blast, which idles along at the speed of sound.”
—Martin Amis (b. 1949)
“This Light inspires, and plays upon
The nose of Saint like Bag-pipe drone,
And speaks through hollow empty Soul,
As through a Trunk, or whisp’ring hole,
Such language as no mortal Ear
But spiritual Eve-droppers can hear.”
—Samuel Butler (1612–1680)