User Filippo

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If the contraction of some quantity is a tensor, is that quantity a tensor?

answered Dec 18, 2022 at 15:34

5 votes

Using tensor products in the bra-ket notation

answered May 22, 2021 at 13:12

4 votes

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Continuity equation as a four-divergence. Possible misunderstanding of contravariance, covariance, or metric signature

answered Nov 24, 2023 at 2:46

3 votes

What is an example of three numbers that do not make up a vector?

answered Jun 13, 2023 at 8:04

2 votes

Check the transformation of coordinates between 2 basis for a tensor of rank 2

answered Jun 27, 2023 at 21:16

2 votes

Mathematical rules for dimensional analysis

answered Sep 27, 2022 at 8:35

2 votes

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What to understand by $\langle \phi | \hat{A}|\psi \rangle$?

answered Sep 28, 2022 at 11:47

2 votes

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Is every idempotent density operator the sum of orthogonal projections?

answered May 24, 2020 at 18:37

1 vote

Reciprocal lattice in 2D

answered Feb 11, 2021 at 12:58

1 vote

Intuitive explanation: how does a LED work?

answered Feb 19, 2021 at 15:41

1 vote

I get an extra term when I try to derive $\nabla\!\!\!\!/\ ^2=\nabla_\mu \nabla^\mu+\frac{1}{4}[\gamma^\mu,\gamma^\nu]F_{\mu\nu}$

answered Mar 31, 2021 at 14:17

1 vote

Proof an infinite dimensional/continous completeness relation $\int|x\rangle \langle x| dx=1$

answered Apr 9, 2021 at 7:33

1 vote

Definition of $k^0$ in Getzler's proof of the Atiyah-Singer index theorem

answered May 19, 2021 at 9:17

1 vote

What does it mean to say "tensors transform sensibly"?

answered Jul 28, 2021 at 10:13

1 vote

Why not define tensors under Galilean or Poincare transformations?

answered Dec 21, 2022 at 9:24

1 vote

Contravariant Components (Susskind's book)

answered Dec 24, 2022 at 9:28

1 vote

Understanding the bra-ket antilinear correspondence

answered Oct 17, 2022 at 15:38

1 vote

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Transformation of coordinates between 2 basis for a tensor of rank 2

answered Jun 28, 2023 at 19:05

0 votes

Question Regarding Vectors

answered Mar 17, 2023 at 11:23

0 votes

Transpose of (1,1) tensor

answered Aug 18, 2021 at 7:25

0 votes

What is the equivalent to $\Box A^\alpha =- \mu_0 J^\alpha$ using differential forms?

answered Oct 13, 2021 at 16:54

0 votes

Raising and Lowering Indices using the Metric Tensor

answered Apr 9, 2022 at 16:01

0 votes

$F$ transforms like a tensor $\Rightarrow B$ transforms like a pseudo vector

answered Sep 9, 2022 at 9:43

0 votes

Explanation of $\sum_n\langle\psi_n(x)|(O\psi_n)(x)\rangle=:(\mathrm{tr}\,O)(x)=\mathrm{tr}\int\frac{\mathrm{d}k}{(2\pi)^4}e^{ikx}Oe^{-ikx}$

answered Apr 1, 2021 at 18:00

0 votes

Is the equation $[\nabla_{\mu},\nabla_{\nu}]=F_{\mu\nu}$ correct? If yes, how does it have to be interpreted?

answered Mar 20, 2021 at 15:39

0 votes

Ordering of Indices in $\Lambda^\mu_{\space\space\nu}$

answered Dec 7, 2020 at 12:57

-1 votes

Books about arrow of time

answered Jan 14, 2021 at 7:56

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27 Answers

If the contraction of some quantity is a tensor, is that quantity a tensor?

Using tensor products in the bra-ket notation

Continuity equation as a four-divergence. Possible misunderstanding of contravariance, covariance, or metric signature

What is an example of three numbers that do not make up a vector?

Check the transformation of coordinates between 2 basis for a tensor of rank 2

Mathematical rules for dimensional analysis

What to understand by $\langle \phi | \hat{A}|\psi \rangle$?

Is every idempotent density operator the sum of orthogonal projections?

Reciprocal lattice in 2D

Intuitive explanation: how does a LED work?

I get an extra term when I try to derive $\nabla\!\!\!\!/\ ^2=\nabla_\mu \nabla^\mu+\frac{1}{4}[\gamma^\mu,\gamma^\nu]F_{\mu\nu}$

Proof an infinite dimensional/continous completeness relation $\int|x\rangle \langle x| dx=1$

Definition of $k^0$ in Getzler's proof of the Atiyah-Singer index theorem

What does it mean to say "tensors transform sensibly"?

Why not define tensors under Galilean or Poincare transformations?

Contravariant Components (Susskind's book)

Understanding the bra-ket antilinear correspondence

Transformation of coordinates between 2 basis for a tensor of rank 2

Question Regarding Vectors

Transpose of (1,1) tensor

What is the equivalent to $\Box A^\alpha =- \mu_0 J^\alpha$ using differential forms?

Raising and Lowering Indices using the Metric Tensor

$F$ transforms like a tensor $\Rightarrow B$ transforms like a pseudo vector

Explanation of $\sum_n\langle\psi_n(x)|(O\psi_n)(x)\rangle=:(\mathrm{tr}\,O)(x)=\mathrm{tr}\int\frac{\mathrm{d}k}{(2\pi)^4}e^{ikx}Oe^{-ikx}$

Is the equation $[\nabla_{\mu},\nabla_{\nu}]=F_{\mu\nu}$ correct? If yes, how does it have to be interpreted?

Ordering of Indices in $\Lambda^\mu_{\space\space\nu}$

Books about arrow of time