On the decrease of entropy in a thermodynamic system by the intervention of intelligent beings.

01' II whe fol'll call esta onl whf:' tem tive veil 81 fal' pcrl chi! hut reg intl' A pos of p as a t.im ing inte Itt R Thl\ T HERE is an objection, already historiCILI, against the universal validity of tim Second Law of Thermodynamics, which illdeed looks rather ominous. The ohjectioll 1M embodied in the notion of :\Iaxwell's dcnlllll, who in a different form appear... en'n nowlL days again and again; perhaps not umCRHOIl ably, inasmuch as behind tilt' prcciHllIy formulated question quantitative <,Olnll'C' tions seem to be hidden which to date IIIL\'" not been clarified. The objection in itH odIC' nal formulation concerns a tIl'IIIOII who catches the fast molecules and lets till' ,dolY ones pass. To be sure, the objt:-ction mil hI! met with the reply that man cnnlLot in pdll ciple foresee the value of a thel'lllully 'hit' tuating parameter. However, onc' ('ILIlIIO! deny that we can very well ml'Ul'lllrCl lit" value of such a fluctuating pal'UIIH'lm' I\llll therefore could certainly gain ellf'rl/;~' ILl. thI! expense of heat by arranging (Jill' illt (,I'Vt'l' entropy in connection with the lIleasure· ment, therefore, need not be greater than Equation (1) requires. Maxwell's Demon