Particle Physics is Founded on This Principle!

Take your first steps toward understanding gauge field theory, which underlies everything we know about particle physics! Sponsored by Blinkist: Start your free trial and get 25% off! https://www.blinkist.com/elliot

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Conservation laws, symmetries, and in particular gauge symmetries are fundamental to the construction of the standard model of particle physics. And as we've seen in past videos, the link that connects symmetries and conservation laws is Noether's theorem. In this video, we'll see how it all extends to field theories. We'll learn to formulate a local conservation law by writing down its continuity equation, which describes how charge is conserved in any region of space. Then we'll see how these conservation laws appear any time we have a field theory with a continuous symmetry. We'll learn about the symmetry of electromagnetism, called U(1), that leads to the conservation of electric charge. And finally, we'll see how to write down the simplest example of a gauge theory by coupling to the electromagnetic potential. The global U(1) symmetry becomes a local symmetry thanks to the covariant derivative, and we arrive at a U(1) gauge theory! The standard model is a generalization of all this.

Field theory fundamentals:    • Field Theory Fundamentals in 20 Minutes!  

Intro to Noether's theorem:    • Symmetries & Conservation Laws: A (Ph...  

The principle of least action:    • Explaining the Principle of Least Act...  

The Lagrangian for a special relativistic particle:    • The Special Relativistic Action, Expl...  

The Lagrangian for a general relativistic particle:    • How Einstein Uncovered the Path a Par...  

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About physics mini lessons:
In these intermediate-level physics lessons, I'll try to give you a self-contained introduction to some fascinating physics topics. If you're just getting started on your physics journey, you might not understand every single detail in every video---that's totally fine! What I'm really hoping is that you'll be inspired to go off and keep learning more on your own.

About me:
I’m Dr. Elliot Schneider. I love physics, and I want to help others learn (and learn to love) physics, too. Whether you’re a beginner just starting out with your physics studies, a more advanced student, or a lifelong learner, I hope you’ll find resources here that enable you to deepen your understanding of the laws of nature. For more cool physics stuff, visit me at https://www.physicswithelliot.com.