Key words: critical phenomena, paired correlation function, scale transformations, scale invariance, optical diagnostics of the critical state of fluids
In this paper we have solved the «fluctuation theorem» on the mesoscopic length scale for the first time in a direct way. An analytical expression for the pair correlation function of the critical state of fluid was obtained, where the density variance is the parameter that could be easily defined by optical measurements. By comparison of our result with the Ornstein—Zernike pair correlation function we have got the Fisher index η= 0.25 to increase the convergence. It was shown that the obtained results provide a reliable theoretical basis for optical diagnostics of the critical state of fluids.
doi:10.1134/S1990793124701331