The meanings of entropy

Entropy is a basic physical quantity that led to various, and sometimes apparently connicting interpretations. It has been successively assimilated to diierent concepts such as disorder and information. In this paper we're going to revisit these conceptions, and establish the three following results: Entropy measures lack of information; it also measures information. These two conceptions are complementary. Entropy measures freedom, and this allows a coherent interpretation of entropy formulas and of experimental facts. To associate entropy and disorder implies deening order as absence of freedom. Disorder or agitation is shown to be more appropriately linked with temperature. 68 Entropy 2005, 771] 69 "No one knows what entropy really is, so in a debate you will always have the advantage" J. Von Neumannn1]