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63 questions with no upvoted or accepted answers
5 votes
0 answers
808 views

Uses of the Angular Momentum 4-Tensor

The angular momentum 4-tensor has 6 independent components, three angular momentum components and three new guys. Some call these new guys the 'boosts', but since they are the conjugate momentum of ...
David Elm's user avatar
  • 1,911
4 votes
0 answers
168 views

Timelike, spacelike etc. for higher-order tensors

Vectors $V^\mu$ in relativity can be classified into those which are timelike, spacelike and null. A similar classification is available for tensors: A tensor $$T^{\mu_1\mu_2...\mu_p}_{\phantom{\mu_1\...
Joshua Tilley's user avatar
3 votes
0 answers
68 views

Counting independent components of Lorentz tensor

Say I have Lorentz tensors $A^{\mu\nu}$ and say this Lorentz tensor is symmetric under $\mu \Leftrightarrow \nu$ and there are only $p^\mu$ and $q^\mu$ as the physical Lorentz vectors involved. If so, ...
Quantization's user avatar
3 votes
0 answers
90 views

Tetrad basis: a doubt on "Comoving" and "Static" tetrads

In the awesome paper $[1]$, Müller then gives us a plethora of spacetimes and their basic geometrical objects like the form of the line element, Christoffel symbols, Krestchmann scalars and so on. ...
M.N.Raia's user avatar
  • 3,085
3 votes
0 answers
923 views

The connection between classical and quantum spins

I have two questions, which are connected with each other. The first question. In a classical relativistic (SRT) case for one particle can be defined (in a reason of "antisymmetric" nature of ...
user avatar
2 votes
0 answers
43 views

Fundamental invariants of a Lorentz tensor

As answered in this question, an antisymmetric tensor on 4D Minkowski space has two Lorentz-invariant degrees of freedom. These are the two scalar combinations of the electromagnetic tensor (as proven ...
Spinoro's user avatar
  • 21
2 votes
0 answers
75 views

How do Maxwell's equations follow from the action of Lorentz generators on field strength?

Following Warren Siegel's book on Field theory (pg. 223), one might derive the action of Lorentz generators $S_{ab}$ on an antisymmetric 2-tensor field strength $F_{cd}$ which arises for example in ...
Sanjana's user avatar
  • 785
2 votes
0 answers
81 views

Help understanding Gauss' and Stoke's Theorem in Minkowski space in index notation

My professor said that it's easy to generalize to these definitions of Stoke's and Gauss' theorem from the 3 dimensional versions but didn't say much else. He threw the following on the chalk board: $$...
DingleGlop's user avatar
2 votes
0 answers
124 views

Weinberg's proof that $F^{\alpha \beta}$ is a tensor

I am interested in Weinberg's approach to proving that $F^{\alpha \beta}$ is a tensor in his book Gravitation and Cosmology. He begins by rewritting the Maxwell equations as: $$\frac{\partial}{\...
jake walsh's user avatar
2 votes
0 answers
74 views

Find the energy-impulse tensor of a fluid of charged dust from the action principle

I have the total action given by: $$S_{tot} = -\frac{1}{16\pi c}\int d\Omega\ F^{\mu \nu}F_{\mu \nu} + \sum_{i=1}^{N}\bigg(-\frac{q}{c}\int dx_i^\mu A_\mu - mc \int ds_i\bigg) \\= \int d\Omega\ \frac{...
Serena Bruzzesi's user avatar
2 votes
0 answers
104 views

Wald General Relativity Exercice 4.5 - Derivation of Tensor Calculus Identity Relevant to "Effective Gravitational Stress Tensor"

This is a lot of text so I apologise, its hard to pose this question concisely while still being clear. In the text, Wald derives to second order deviation from flatness an expression for the "...
Leuca Patmore's user avatar
2 votes
0 answers
184 views

The form of QED Vertex Correction

In chapter 6 of Peskin-Schroeder's text Introduction to Quantum Field Theory it is argued that the form of vertex correction for QED can only have the following form (since we have only the constants, ...
self.grassmanian's user avatar
2 votes
0 answers
152 views

Momentum in capacitor field; How can an EM field have zero momentum density but non-zero momentum flux?

Consider the case of a simple, stationary parallel plate capacitor oriented with its plates lying in the x-y plane. The E-field is simply given by: $$\vec{E} = \frac{Q}{\epsilon_0A}\hat{z} $$ with ...
1MegaMan1's user avatar
  • 340
2 votes
1 answer
305 views

Derivation of 4-current $j$ being a 4-vector in Landau-Lifschitz: Formulation with rigorous mathematical treatment?

Here on Stack exchange, there appeared the question on how to derive the 4-current actually being a Lorentz-tensor. One of the answers (How do we prove that the 4-current $j^\mu$ transforms like $x^\...
Quantumwhisp's user avatar
  • 6,763
2 votes
0 answers
237 views

Tensor Calculus/Vector Calculus and so on in special relativity book recommandation

I want to learn calculus 1,2,3 vector calculus, analysis and so on in special relativity. But I never found a good and clear book/source on it. Can someone recommend an easy book or internet source on ...

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