Conservation and Generation of Entropy

The atomic disorder in a warm object and, therefore, the entropy in it have remarkable and well-defined characteristics, some of which have already been mentioned. They will be described in more detail in the following. 

Experiment 3.1 Brownian motion-. Brownian motion is a tremulous, random movement of tiny particles distributed in a liquid (e.g., drops of fat in milk) or particles stirred up in a gas (e.g., smoke particles in air). This kind of movement can be observed under a microscope for indefinite amounts of time without it letting up. 

Conservation The atomic disorder and agitation in a thermally insulated body which is left to itself remain undiminished for an unlimited amount of time. An object contains entropy—we can say— whose amount S cannot decrease if it is in a thermally insulating (adiabatic) envelope, because entropy cannot penetrate thermally insulating walls (Fig. 3.8). 

The agitation manifests itself among others by the microscopically visible Brownian motion (Experiment 3.1). Therefore, it can be regarded not only as theoretically constructed but as directly observable. 

The amount of entropy an object contains depends upon its state. Identical objects in the same state contain identical amounts of entropy. The entropy contained in an object that is composed of pieces is the sum of the entropies of 

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