Laws of Thermodynamics

24.03.2015 |

Episode #8 of the course “Scientific laws and theories everyone should know”

The physicist C.P. Snow (who was also a writer) stated that a person who was not a scientist and didn’t know about thermodynamics was similar to a scientist who never studied Shakespeare. This famous statement was stated to show that it was important for non-scientists to learn about thermodynamics and be familiar with the significance of the field.

Thermodynamics examines how energy works in a given system, whether it is an engine or the core of the earth. Thermodynamics can be boiled down to group of fundamental laws. Snow wittily summarized the laws as follows: “You can’t win,” “You can’t break even,” and “You can’t quit the game.”

In stating that you cannot win, Snow explains that since the matter cannot be lost, you can’t achieve one ideal without changing something else (i.e., E=mc²). Additionally, Snow suggests that for an engine to do any work, heat must be given. However, in all except expertly closed systems, an amount of heat is invariably lost in the process, which serves as an introduction to the second law.

Snow then states you can’t break even. Here he suggests that because of increasing entropy, it is impossible to go back to a past state of energy. Energy that is packed into one place will diffuse to a place that has lower concentration.

And for the third law, “You can’t quit the game,” this refers to absolute zero. This number represents the smallest plausible temperature, which is zero Kelvin or -273.15 degrees Celsius and -459.67 degrees Fahrenheit. Once a system arrives at absolute zero, all molecules stop moving, kinetic energy can’t exist, and entropy reaches the lowest value it will ever have. However, in the world as we experience it, you cannot get to absolute zero (but some experts have tried to get close).


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