= Microstate multiplier from photon absorption
{title2=$\Omega_f/\Omega_i\simeq\exp[hc/(\lambda k_BT)]$}
A single <photon> thermalized in a macroscopic body adds <energy> $hc/\lambda$. If its <heat capacity> is sufficiently large that the <temperature> change is negligible, the <entropy> increase is $hc/(\lambda T)$. The <Boltzmann entropy> then gives the displayed ratio of accessible <microstates>. The exponential can be enormous even though the deposited <energy> is macroscopically tiny.
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