Speed of light is a constant in any direction:
Maxwell's equations don't directly prove that the speed of light is invariant in all inertial frames (i.e., same for all observers regardless of motion). That principle comes from Einstein's theory of Special Relativity.
But Maxwell's equations suggest that the speed of light is:
- Constant in a given medium (e.g., vacuum),
- Independent of the source of the wave.
The fact that light speed appears as a constant of nature in Maxwell's equations — without reference to any observer — is what led Einstein to postulate its invariance in all inertial frames.
Summary:
- Maxwell's equations predict that electromagnetic waves travel at a speed which can be calculated using the formula:
- v = 1 / √(μ₀.ε₀)
- ... where v is the speed of the electromagnetic wave, μ₀ {pronounced mu_zero} is the permeability of free space, and ε₀ {pronounced epsilon_naught} is the permittivity of free space.
- This speed matches the experimentally measured speed of light (c).
- Therefore, light is an electromagnetic wave that travels at a constant speed in vacuum, as derived from fundamental laws.
