Electromagnetic vacuum energy with a wavelength cutoff
= Electromagnetic vacuum energy with a wavelength cutoff
{title2=$u=2\pi^2\hbar c/\lambda_{\min}^4$}
Counting two transverse <polarizations> and <zero-point energy> $\hbar ck/2$ per mode gives $u=\hbar ck_{\max}^4/(8\pi^2)=2\pi^2\hbar c/\lambda_{\min}^4$. This is a bare cutoff-dependent mode sum, not a classical incident radiation bath or a renormalization-independent absolute observable.