# Constraints on speed of light?

1. Oct 4, 2009

### Quickless

The speed of light is fast but far from instantaneous. What constrains the speed of light to be what it is? e.g. c = f(xi)

Life is good,

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2. Oct 4, 2009

### Integral

Staff Emeritus
In the 1860's Maxwell found that c = $\frac 1 {\sqrt {\epsilon_0 \mu_0} }$

Where $\epsilon_0$ is the permitivity and $\mu_0$ is the permeability of free space.