In the final case for N = 1000 (Fig. , 9), we find nearly identical results as for the N = 100 case (Fig. ). Thus, interestingly, the collective effects involved in linear transmission spectroscopy inside the cavity are converged with only 100 coupled molecules for the model system considered here. This is likely due to the fact that the dynamics among the collective states are only sensitive to collective quantities, √ NA 0 , as shown in recent theoretical works . While the converged simulation requires averaging over a statistical ensemble of molecules, in the experiment, this is automatically accounted for due to time-evolving thermal fluctuations of the molecules.