In the late eighteenth century, inventors began creating devices that would eventually evolve into the steam engine. In efforts to improve these devices, scientists studied the principles of work and energy. Through his studies, a scientist named Robert Boyle discovered that the pressure of a gas increases when the volume of its container decreases. Other scientist discovered new principles that characterized energy as it entered a machine or system, passed through it, and finally exited. The form of the energy coming out of a machine or system could take the form the work, motion, or heat loss. This became now as the science of thermodynamics. Thermodynamics proved to be a rich field of study, eventually producing four fundamental laws. The laws are not, however, called the First through Fourtd laws. Rather, they are the Zeroth through Third Laws of thermodynamics.
The Zeroth Laws of Thermodynamics states that if two systems. A and B, are in equilibrium with a third system, C, then they are also in equilibrium with each other. Equilibrium here means that the systems are in contact and their temperatures and pressures are the same. For example, say a room is 20 degrees Celsius and another room of the same size is 10 degrees. These rooms are not equilibrium. If a door between them is open and you wait a bit, then both room’s temperatures will either drop or rise to 15 degrees. Then the rooms are in equilibrium. If another room was already at 15 degrees and is exposed to the rooms at equilibrium, this third room will not be in equilibrium with both rooms, too. Therefore, given time, systems will be in equilibrium with all systems with which they are in contact.
The First Law is the law of conservation of energy. This law says that energy can neither be created nor destroyed. It can only shift around and change forms. For example, all the energy contained in fuel for an engine will become motion of the engine or will be given off as heat when the fuel is burned. Energy cannot simply disappear into nothing or come from nothing.
The Second Law states that entropy of a system will increase over time. Entropy is a word that means the tendency for order of a system to decrease. In other words, entropy causes all systems to move from order toward chaos. A classic example is an ice cube melting in a room order toward chaos. A classic example us an ice cube melting in a room. When it is frozen, the ice is highly ordered and has low entropy. As it melts, the molecules move more freely and become less ordered. The entropy of the system that includes the ice and the room increases as the ice melts.
The third law says that entropy will approach zero as the temperature approaches absolute zero (zero on the keivin scale). Entropy never truly equals zero because it is not actually possible to achieve a temperature of absolute zero. However, At temperature that are near absolute zero , all motion practically stops. As an example, it is more difficult to move in colder temperatures because the processes that exchange heat and energy and create work function more slowly at lower temperatures.
These laws have found broad applications, from physics and engineering, to chemistry, biology, and even information technology Engineers use them to make machines more efficient. Biologists use them to describe evolution and natural systems. Meteorologists use them to predict weather patterns. They are also the proof that perpetual motion machines-machines that keep running forever-are impossible.
There is a funny saying that relates to the laws of thermodynamics. It goes like this: “People must play. People can’t win. People can’t break even. People can’t quit.” People must play (Zeroth Law) because they must try to reach equilibrium with other systems. They cannot win (First Law) because energy cannot break even (Second Law) because entropy increases. And finally, they cannot quit (Third Law) because they cannot reach absolute zero.