The long-standing and highly non-trivial problem of calculating the pressure fluctuations in the Gibbs equilibriumudstatistical mechanics is fully revised. The previous attempts are critically analyzed and it is shown that theudapplication of the ideas by Bogolyubov gives the full and unambiguous solution of this problem. The crucialudrole is played by the Bogolyubov's idea of quasiaverages (or rather quasidynamic) quantities specifically,udthe pressure P and dynamic compressibility ψ. The virtual conjugate field which eliminates the translationaludinvariance of the Hamilton function H in the limit ε→ 0 is the singular potential of the impenetrable walls of theudcontainer. The general relations for P and ψ in terms of the derivatives of H are obtained and some examplesudare studied i. e., the cases of the ideal vs. non-ideal as well as of uniform vs. non- and quasi-uniform (inudEuler sense) Hamilton function H describing the given system.
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