Negative Temperature

In this study, we are interested in the statistical interpretation of the notion of temperature, based on some of the concepts used to demonstrate its existence. Our work comprises 4 main chapters The first chapter is concerned with explaining the two physical meanings of temperature: the thermodynamic meaning, where temperature is described by the agitation of the particles that make up matter, and follows the equipartition theorem, whereas the statistical meaning is based on the link between entropy and energy. The second chapter will deal with the notion of entropy and its interpretations, statistical where it expresses the lack of information, and thermodynamic where it is described by the 2 principles; The second which gives us in which direction the transformation made and the 3rd of Nernst where entropy at 0 kelvin is zero. The third chapter deals with the notion of negative temperature, its history, definition, demonstration of its existence theoretically, and finally the fourth chapter which looks at the field of application of this notion.