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Laws of Thermodynamics

QUESTION: When were the laws of thermodynamics first described?


As with other important laws of science, the Laws of Thermodynamics were developed through a combination of observation, experimentation, and innovation. Development of the Laws of Thermodynamics actually began thousands of years ago. Early observers and innovators took advantage of natural laws they could see every day and turned them into standards. During the nineteenth century, the Laws of Thermodynamics took leaps and bounds from theory and suggestion into accepted scientific fact. Since then, science has refined these laws into their current form.

Certain aspects of nature have always pointed to the real Laws of Thermodynamics. Heat has always moved from warm bodies to cool ones. Energy from fuels has always become energy for moving machines. These machines have always needed help to continue running, and their fuels cannot be reused forever. These aspects of energy and matter are controlled, in part, by the First and Second Laws of Thermodynamics.

As science became more sophisticated, researchers developed coherent theories about the workings of matter and energy. These ideas were not always on the right track, despite extensive initial evidence. For awhile, the opinion of many scientists was that heat energy and work energy were different types of universal fluids that flowed from object to object as they interacted. They also believed that certain interactions required no exchange of energy at all. While these theories could be explained through evidence available at the time, they were eventually proven wrong by further discoveries.

The largest advancements in developing the Laws of Thermodynamics occurred in the mid-1800s. James Prescott Joule proved experimentally that work energy and heat energy are interchangeable and are conserved. His experiment used a falling weight that drove a paddle underwater. The potential energy lost by the weight as it fell matched the heat energy gained by the water. These findings were verified independently by other scientists around the same time. So was born the First Law of Thermodynamics, the principle of conservation of energy.

Not long after, Robert Clausius developed his theories about heat and work into a concise version of the Second Law of Thermodynamics, concerning the increase of entropy in natural systems. This description was derived over the course of more than a decade of writing and experimentation. Clausius depended heavily on the findings of researchers such as Joule.

The Third Law of Thermodynamics was developed around 1906 by Walther Nernst. In early application, this law described the energy of certain processes in relation to their behavior near the temperature of absolute zero. This law would eventually be condensed and greatly simplified into its current form, stating that "the entropy of a pure perfect crystal is zero at zero degrees Kelvin." Implications and corollaries to the Third Law of Thermodynamics would eventually become keys to modern chemistry and physics.

The history of the Laws of Thermodynamics reveals more than just how science described a set of natural laws. It can teach us a great deal about our pride in "Modern Science." The Laws of Thermodynamics were in effect long before they were written in textbooks or derived in laboratories. They were as valid and real as gravity, magnetism, or DNA. And yet there was a time when brilliant men and women, using their generation's most sophisticated science, had no idea that they were true.

Every civilization's idea of "Modern Science" once supported concepts as wrong as an unmoving Earth, orbited by the Sun. It claimed that heat was an invisible fluid, or that only males held the components for human life. Scientists developed these theories based on the data that they had at the time - theories that were sometimes proven false. They believed these things because their science led them to that belief. They didn't have perfect or absolute proof, but they could make the data fit their beliefs.

Sometimes faith in science can lead brilliant men to believe things that are not true, because they haven't seen everything that science - or the universe - has to show them. Lord William Thomson Kelvin, for whom the Kelvin temperature scale is named, stated in 1895, "Heavier-than-air flying machines are impossible." One of the greatest scientists of all time was proven wrong, along with many of his colleagues, just eight years later by the Wright Brothers. There are many popular and widely accepted theories that science cannot prove beyond doubt. Yet, the way they interpret the evidence is good enough for some people to put their faith in. There is great danger in ignoring evidence that contradicts a scientific theory, claiming that the theory is "Modern Science," and so it must be true. What would Lord Kelvin say to that? Like the Laws of Thermodynamics themselves, there have been some powerful, universal, undeniable truths that science has been wrong about in the past. What theories and ideas does "Modern Science" claim today that might not be true? Are there any views of the universe that haven't proven false?

Learn More about the Second Law of Thermodynamics!

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