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This content is taken from the University of Liverpool's online course, Energy: Thermodynamics in Everyday Life. Join the course to learn more.

Skip to 0 minutes and 4 seconds Last week, we met the second law of thermodynamics, which controls why anything happens at all, and looked at how it limits the efficiency of everything. This week, we’ll combine the first and second laws, following the example of an American mathematician, Willard Gibbs, to arrive at the concept of available, or free energy. The concept of Gibbs energy is ingenious, because it allows us to ignore entropy changes in the environment, which are usually very hard to quantify. And we do this by only considering the changes in the system that we’re analysing or designing. Gibbs energy must decrease in all real processes, but we can create coupled processes in order to allow some that don’t satisfy this condition to exist.

Skip to 0 minutes and 49 seconds And we’ll take a look at how nature does this trick. Finally, I’ll introduce the third law of thermodynamics, which says it’s impossible to reach absolute zero - zero Kelvin. And we’ll take a glimpse at recent research that suggests we might be able to achieve temperatures beyond zero, or negative absolute temperatures. We’ll wrap up the course with a quiz and the final stage of the perpetual motion design competition.


In this week we will combine the first and second laws of thermodynamics following the example of Willard Gibbs which will lead to the concept of free energy. Watch Eann introduce the week, which includes a look at the third law and recent research about the world beyond absolute zero.

(Please note that 40 seconds into the video Eann means to say the Gibbs energy must decrease in all real processes)

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This video is from the free online course:

Energy: Thermodynamics in Everyday Life

University of Liverpool