= Yang-Mills existence and mass gap
{c}
{wiki=Yang–Mills_existence_and_mass_gap}
* https://www.youtube.com/watch?v=-_qNKbwM_eE Unsolved: Yang-Mills existence and mass gap by J Knudsen (2019). Gives 10 key points, but the truly hard ones are too quick. He knows the thing though.
\Video[https://www.youtube.com/watch?v=j3fsPHnrgLg]
{title=Yang-Mills 1 by David Metzler (2011)}
{description=
Playlist: https://www.youtube.com/watch?v=j3fsPHnrgLg&list=PL613A31A706529585&index=13
A bit disappointing, too high level, with very few nuggests that are not Googleable withing 5 minutes.
Breakdown:
* 1 https://www.youtube.com/watch?v=j3fsPHnrgLg[]: too basic
* 2 https://www.youtube.com/watch?v=br6OxCLyqAI?t=569[]: mentions <groups of Lie type> in the context of <classification of finite simple groups>. Each group has a little diagram.
* 3 https://youtu.be/1baiIxKKQlQ?list=PL613A31A706529585&t=728 the original example of a <local symmetry> was <general relativity>, and that in that context it can be clearly seen that the local symmetry is what causes "forces" to appear
* https://youtu.be/1baiIxKKQlQ?list=PL613A31A706529585&t=933 <local symmetry> gives a conserved current. In the case of <electromagnetism>, this is electrical current. This was the only worthwhile thing he sad to 2021 Ciro. Summarized at: <local symmetries of the Lagrangian imply conserved currents>.
* 4 https://youtu.be/5ljKcWm7hoU?list=PL613A31A706529585&t=427 <electromagnetism> has both a global symmetry (<special relativity>) but also <local symmetry>, which leads to the conservation of charge current and forces.
<quantum field theory lecture by tobias osborne 2017/lecture 3> properly defines a <local symmetry> in terms of the context of the <lagrangian density>, and explains that the conservation of currents there is basically the statement of <Noether's theorem> in that context.
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\Video[https://www.youtube.com/watch?v=vMiY7zlBOFI]
{title=Millennium Prize Problem: Yang Mills Theory by David Gross (2018)}
{description=2 hour talk at the <Kavli Institute for Theoretical Physics>. Too mathematical, 2021 Ciro can't make much out of it.}
\Video[https://www.youtube.com/watch?v=pCQ9GIqpGBI]
{title=Lorenzo Sadun on the "Yang-Mills and Mass Gap" <Millennium Prize Problems>[Millennium problem]}
{description=Unknown year. He almost gets there, he's good. Just needed to be a little bit deeper.}