Recent content by sadness

I mean, you can not write the derivative to z* without the help of splitting into x and y. I see your point now. Thanks for pointing out my mistake.

Okay. One can somewhat define it formally, but it's not a very decent derivative I think. May I ask that what's your opinion on the point I raised in the post #30?

but how do you define the derivative with respect to z*?

If phi and phi star are really independent variables, we should get Hamiltonian density as: \mathcal{H}=\pi\partial_0\phi+\pi^*\partial_0\phi^*-\mathcal{L} while the true answer is: \mathcal{H}=\pi\partial_0\phi-\mathcal{L}.(I made a mistake here, the first expression is right. Thanks for...

In the appendix B of Goldstein's classical mechanics (3rd edition), the authors discussed the dihedral group and said: "Notice how the group elements in class 3 involve only \sigma_1 and \sigma_3. Thus, they are independent of the matrices I and \sigma_2, as is expected from the structure of...

Thanks. I understood what the authors meant now.

On page 10 of Goldstein's classical mechanics, it was said: "If V_{jj} were also a function of the difference of some other pair of vectors associated with the particles, such as their velocities or (to step into the domain of modern physics) their intrinsic "spin" angular momenta, then the...