Macroscopic Properties of Entropy

Entropy changes the state of an object noticeably. If matter, for example, a piece of wax or a stone, contains little entropy, it is felt to be cold. If, however, the same object contains more or a lot of entropy, it can feel warm or even hot. If the amount of entropy in it is continuously increased, it will begin to glow, firstly dark red, then bright white, subsequently melt, and finally vaporize like a block of iron would, or it may transform and decompose in another way, as a block of wood might. Entropy can also be removed from one object and put into another. When this is done, the first object becomes cooler and the second, warmer. To put it succinctly Entropy plays a role in all thermal effects and can be considered their actual cause. Without entropy, there is no warm and cold and no temperature. The obvious effects of entropy allow us to observe its existence and behavior quite well even without measurement devices. 

Spreading Entropy tends to spread. In a uniform body, entropy will distribute itself evenly throughout the entire volume of the body by flowing more or less rapidly from locations of higher entropy density (where the body is especially warm) to areas where the body is cooler and contains less entropy (Fig. 3.2). 

If two differently warm bodies touch each other, entropy will flow from the warmer one to the cooler one (Fig. 3.3). 

There are substances which conduct entropy very well, such as silver, copper, aluminum, and diamond, and others, such as wood, foamed plastic, or air, which only allow entropy to pass through them very slowly (Fig. 3.4). 

Bad conductors, however, are used to contain entropy. A vacuum acts like an especially good insulation. Entropy is also able to penetrate layers without matter by radiation, but this process takes place rather slowly at room temperature or below. This property is used in thermoses to keep hot beverages hot and cold 

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