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advanced_tools:legendre_transformation [2017/12/04 08:01] 127.0.0.1 external edit |
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====== Legendre Transformation ====== | ====== Legendre Transformation ====== | ||
- | <tabbox Why is it interesting?> | + | <tabbox Intuitive> |
- | <blockquote> | + | |
- | The Legendre transform shows up whenever we minimize or maximize something subject to constraints. That happens a lot. | + | |
- | + | ||
- | <cite>https://johncarlosbaez.wordpress.com/2012/01/19/classical-mechanics-versus-thermodynamics-part-1/</cite> | + | |
- | </blockquote> | + | |
- | + | ||
- | The Legendre transformation is a useful mathematical tool that is used in thermodynamics, classical mechanics and quantum field theory. | + | |
- | + | ||
- | Maybe the most famous application is that in classical mechanics, quantum mechanics and quantum field theory the Hamiltonian and the Lagrangian are connected by a Legendre transformation. | + | |
- | + | ||
- | Moreover, the Legendre transformation is used in thermodynamics to motivate the connection between the internal energy, enthalpy, and Gibbs and Helmholtz free energies. | + | |
- | + | ||
- | <blockquote> | + | |
- | Both uses can be compactly motivated if the Legendre | + | |
- | transform is properly understood. Unfortunately, that transform is often relegated to a footnote in | + | |
- | a textbook, or worse is presented as a complicated mathematical procedure. [...] In a nutshell, a Legendre transform simply changes the | + | |
- | independent variables in a function of two variables by application of the product rule. | + | |
- | + | ||
- | <cite>https://www.aapt.org/docdirectory/meetingpresentations/SM14/Mungan-Poster.pdf</cite> | + | |
- | </blockquote> | + | |
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | <tabbox Layman?> | + | |
<note tip> | <note tip> | ||
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</note> | </note> | ||
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- | <tabbox Student> | + | <tabbox Concrete> |
* See: [[http://aapt.scitation.org/doi/pdf/10.1119/1.3119512|Making sense of the Legendre transform]] by R. K. P. ZiaEdward, F. RedishSusan, R. McKay | * See: [[http://aapt.scitation.org/doi/pdf/10.1119/1.3119512|Making sense of the Legendre transform]] by R. K. P. ZiaEdward, F. RedishSusan, R. McKay | ||
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- | <tabbox Researcher> | + | <tabbox Abstract> |
<note tip> | <note tip> | ||
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</note> | </note> | ||
| | ||
- | <tabbox Examples> | + | <tabbox Why is it interesting?> |
+ | <blockquote> | ||
+ | The Legendre transform shows up whenever we minimize or maximize something subject to constraints. That happens a lot. | ||
- | --> Example1# | + | <cite>https://johncarlosbaez.wordpress.com/2012/01/19/classical-mechanics-versus-thermodynamics-part-1/</cite> |
+ | </blockquote> | ||
- | + | The Legendre transformation is a useful mathematical tool that is used in thermodynamics, classical mechanics and quantum field theory. | |
- | <-- | + | |
- | --> Example2:# | + | Maybe the most famous application is that in classical mechanics, quantum mechanics and quantum field theory the Hamiltonian and the Lagrangian are connected by a Legendre transformation. |
+ | |||
+ | Moreover, the Legendre transformation is used in thermodynamics to motivate the connection between the internal energy, enthalpy, and Gibbs and Helmholtz free energies. | ||
+ | |||
+ | <blockquote> | ||
+ | Both uses can be compactly motivated if the Legendre | ||
+ | transform is properly understood. Unfortunately, that transform is often relegated to a footnote in | ||
+ | a textbook, or worse is presented as a complicated mathematical procedure. [...] In a nutshell, a Legendre transform simply changes the | ||
+ | independent variables in a function of two variables by application of the product rule. | ||
+ | |||
+ | <cite>https://www.aapt.org/docdirectory/meetingpresentations/SM14/Mungan-Poster.pdf</cite> | ||
+ | </blockquote> | ||
- | |||
- | <-- | ||
- | | ||
- | <tabbox History> | ||
</tabbox> | </tabbox> | ||