All Questions
4
questions
3
votes
1
answer
82
views
Does quasi-symmetry preserve the solution of the equation of motion?
In some field theory textbooks, such as the CFT Yellow Book (P40), the authors claim that a theory has a certain symmetry, which means that the action of the theory does not change under the symmetry ...
- 51
4
votes
2
answers
466
views
Confusion about symmetry and conservation
I think I am misunderstanding the concept of symmetry in Lagrangian mechanics or maybe I am misunderstanding the content of Noether's theorem. Let me elaborate:
Suppose $L(q,\dot q,t)$ is the ...
- 56
3
votes
2
answers
2k
views
Detailed conditions for symmetries of Lagrangian
Edit: To clarify the question, I am asking why we are justified in calling a continuous symmetry a symmetry of a system when it changes the Lagrangian by a total derivative of a function of $t, q(t)$ ...
- 31
4
votes
1
answer
609
views
Trivial conserved Noether's current with second derivatives
I'm considering a symmetry transformation on a Lagrangian
$$ \delta A = \int L(q +\delta q, \dot{q} + \delta \dot{q} , \ddot{q} + \delta \ddot{q}) dt $$
the general variation takes the form
$$ \...
- 2,299