# Tagged Questions

A theorem that relates continuous symmetries (continuous transformations that don't affect the value of the lagrangian) to quantities conserved in time.

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### Problems with the strong interaction and the rest of the standard model [duplicate]

This question has been heavily revised from what I asked earlier: Michio Kaku, in his QFT a Modern Introduction says (in paraphrase) that the $SU(3)$ gauge symmetry of the strong interaction must be "...
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### What does Michio Kaku mean when he says that the Strong Interaction must be “penciled in” to the Standard Model [on hold]

This is a very heavily revised question asked earlier: Michio Kaku, in his QFT a Modern Introduction says (in paraphrase) that the $SU(3)$ gauge symmetry of the strong interaction must be "penciled ...
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### What symmetry gives you charge conservation?

This is a popular question on this site but I haven't found the answer I'm looking for in other questions. It is often stated that charge conservation in electromagnetism is a consequence of local ...
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### What is the conserved quantity of a scale-invariant universe?

Consider that we have a system described by a wavefunction $\psi(x)$. We then make an exact copy of the system, and anything associated with it, (including the inner cogs and gears of the elementary ...
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### Learning about 4 topics in physics [closed]

This isn't really a question on any of those numerous underlying concepts behind the various sub-disciplines of physics, but hear me out: I'm still in Higher Secondary, but I'd really love to know ...
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### To find the conserved quantities in a lagrangian?

Lagrangian of a particle of mass $m$ is given by $$L= \frac{m}{2}[(\frac{dx}{dt})^2 + (\frac{dy}{dt})^2 + (\frac{dz}{dt})^2]-\frac{V}{2}(x^2+y^2)+ W\sin(\omega t)$$ Is energy conserved here since ...
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### Noether current for the Yang-Mills-Higgs Lagrangian

I am trying to calculate the Noether current, more specifically, the energy density of the Yang-Mills-Higgs Lagrangian. Please refer to the equations in the Harvey lectures on Magnetic Monopoles, ...
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### Noether Current when the Lagrangian depends on second derivative of the fields

Let a Lagrangian density for a field theory of $N$ fields $\left\{\phi_i\right\}_{i=1}^N$ be given. Assume that the Lagrangian density depends on the fields, their spacetime derivatives, and their ...
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### Noether's theorem in classical field theory (proof)

Noether's theorem for classical field theory state that if for each closed region $\Omega \in \mathbb{R}^4$ the action $I_{\Omega}$[$\phi$] is invariant under a differentiable transformation of one ...
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### A brief idea about Noether's Theorem? [closed]

I've recently been lead to believe that a certain "Noether's Theorem" could prove to be a very helpful tool in physics. I've only just started reading up on Lagrangian mechanics, but I'd like to get ...
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### On a trick to derive the Noether current

Suppose, in whatever dimension and theory, the action $S$ is invariant for a global symmetry with a continuous parameter $\epsilon$. The trick to get the Noether current consists in making the ...
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### Lorentz transformation and symmetries of the Lagrangian [duplicate]

Since the Lagrangian of our quantum field theories is covariant under Lorentz transformations I'm asking myself if there is any link to some symmetries (like that we get from gauge transformations ...
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### Prove energy conservation using Noether's theorem

I wonder how you prove that energy is conserved under a time translation using Noether's theorem. I've tried myself but without success. What I've come up with so far is that I start by inducing the ...