I have a probably stupid dilemma; studying the Drude theory of metals we found $\epsilon_r = 1-\frac{\omega_p^2}{\omega^2}$. Now if $\omega>\omega_p$ it follows that $\epsilon_r <1$ so the refractive index $n$ must be $< 1$ too. If that is true, the e.m. wave can propagate in the metal with speed greater than the speed of light. What am I missing?


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