User zabop

27 votes

2 answers

564 views

Why is this a first integral? - particle near Schwarzschild black hole

asked Apr 3, 2021 at 17:27

11 votes

1 answer

515 views

How to solve equation of motion of cosmological scalar field

ordinary-differential-equations mathematical-physics

asked Mar 12, 2021 at 10:31

4 votes

1 answer

249 views

Solving heat equation using Fourier-series with non-homogeneous assymetric bondary conditions

ordinary-differential-equations partial-differential-equations fourier-analysis fourier-series linear-pde

asked Oct 3, 2020 at 23:06

4 votes

1 answer

85 views

Why is $\delta^b_e\nabla_c {R_{cad}}^e$ equal to $\nabla^b {R_{cadb}}$ - ie how to contract the Bianchi identity properly

riemannian-geometry general-relativity

asked Dec 4, 2020 at 0:25

3 votes

2 answers

494 views

Proof that each element of finite arbitrary group belongs to unique conjugacy class - question on step which takes inverse of a product

abstract-algebra group-theory proof-verification finite-groups

asked Sep 21, 2018 at 13:57

3 votes

2 answers

497 views

Why do all elements commute in centre of an arbitrary finite group?

abstract-algebra group-theory proof-writing finite-groups

asked Sep 21, 2018 at 15:44

3 votes

1 answer

80 views

Why is the definition of sin and cos in terms of exponentials is similar to the definition of $L_x$ & $L_y$ in terms of raising & lowering operators?

trigonometry complex-numbers exponential-function quantum-mechanics

asked Mar 14, 2019 at 17:33

3 votes

0 answers

66 views

How to estimate parameter functions of Sturm-Liouville operators using functional gradient descent?

python sturm-liouville

asked Jan 13 at 22:56

3 votes

1 answer

382 views

Solving the heat equation in spherical polars with nonhomogeneous boundary conditions

ordinary-differential-equations partial-differential-equations heat-equation eigenfunctions sturm-liouville

asked Oct 3, 2020 at 11:49

2 votes

2 answers

100 views

Is Mercator projection an affine trasformation?

linear-algebra differential-geometry map-projections

asked Sep 1, 2021 at 19:13

2 votes

0 answers

231 views

Shortcut to find imaginary part of analytic function given real part, without standard form of Cauchy-Riemann equations?

calculus complex-analysis cauchy-riemann-equations

asked Dec 3, 2019 at 11:45

2 votes

1 answer

235 views

How to 2D Fourier Transform a chequerboard-like function by hand?

integration fourier-transform

asked Dec 4, 2019 at 11:33

2 votes

1 answer

31 views

Poisson's equation-like formula in axis-symmetric Galactic potential in terms of Oort constants

mathematical-physics mathematical-astronomy

asked May 5, 2021 at 14:47

2 votes

1 answer

49 views

Deriving the first moment of Collisionless Boltzmann Equation in Spherical Polar Coordinates

mathematical-astronomy

asked Jan 1, 2021 at 2:08

2 votes

1 answer

209 views

Calculation of Christoffel symbols of Schwarzschild metric using Lagrangian

general-relativity

asked Jan 12, 2021 at 0:19

2 votes

0 answers

54 views

How many independent connection coefficients are there for a given dimensional metric?

mathematical-physics general-relativity

asked Mar 12, 2021 at 19:10

2 votes

2 answers

123 views

Is it special for a Lagrangian to equal its first integral?

functional-analysis mathematical-physics euler-lagrange-equation general-relativity mathematical-astronomy

asked Apr 3, 2021 at 21:06

1 vote

1 answer

446 views

How to take algebraic Bianchi identity into account when calculating the number of independent components of Riemann curvature tensor

combinatorics riemannian-geometry mathematical-physics general-relativity

asked Mar 13, 2021 at 10:58

1 vote

0 answers

25 views

Parametrized solution for motion of radially infalling object

mathematical-physics mathematical-astronomy

asked Mar 30, 2021 at 16:39

1 vote

0 answers

20 views

How to find curve which I have the tangent vector field to in polar coordinates?

fluid-dynamics

asked Jan 31, 2021 at 7:19

1 vote

0 answers

38 views

How to find the right combination of general solutions to fulfill nonhomogeneous boundary conditions when solving heat equation in spherical polars

integration ordinary-differential-equations partial-differential-equations greens-function

asked Oct 6, 2020 at 0:35

1 vote

1 answer

362 views

How to interpret invariant subspaces in the definition of irreducible representation?

abstract-algebra representation-theory definition

asked Oct 12, 2018 at 11:26

1 vote

0 answers

162 views

How to show that the gradient of a vector field is an order 2 tensor - and what can we learn from doing it wrong?

linear-algebra proof-writing tensors

asked Jun 26, 2019 at 21:31

1 vote

2 answers

143 views

How can $(A \times \nabla) \times B$ be rearranged?

calculus multivariable-calculus vector-spaces vector-analysis vector-fields

asked Aug 12, 2019 at 16:18

1 vote

1 answer

45 views

Do the free indices referring to the same dimension have to be denoted by the same letter on both sides of an expression when using Einstein notation?

linear-algebra vectors tensors index-notation

asked Oct 15, 2019 at 9:29

1 vote

1 answer

236 views

Proof that $H \cap K$ is a group if $H$ and $K$ are subgroups of $G$ [duplicate]

abstract-algebra group-theory proof-verification

asked Sep 21, 2018 at 19:28

1 vote

1 answer

46 views

Clarification of definition of quotient group - Does $Na, a \in G$ mean "cosets of $N$ in $G$"?

abstract-algebra group-theory definition

asked Oct 19, 2018 at 13:59

1 vote

1 answer

85 views

What property does the function hold which values equal the complex conjugate of the function with argument with opposite sign?$X(-\nu)=X^*(\nu)?$

complex-analysis functions terminology

asked Feb 4, 2019 at 18:12

1 vote

2 answers

199 views

Is there any matrix $A$ for which $A^{\dagger}A=AA^{\dagger}$ but $A\neq A^{\dagger}$?

linear-algebra matrices

asked Mar 9, 2019 at 13:05

1 vote

5 answers

47 views

How do I get the equality $\sum_{l-s}^{l+s}(2j+1) = (2l+1)(2s+1)?$

summation

asked Mar 12, 2019 at 13:37

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52 Questions

Why is this a first integral? - particle near Schwarzschild black hole

How to solve equation of motion of cosmological scalar field

Solving heat equation using Fourier-series with non-homogeneous assymetric bondary conditions

Why is $\delta^b_e\nabla_c {R_{cad}}^e$ equal to $\nabla^b {R_{cadb}}$ - ie how to contract the Bianchi identity properly

Proof that each element of finite arbitrary group belongs to unique conjugacy class - question on step which takes inverse of a product

Why do all elements commute in centre of an arbitrary finite group?

Why is the definition of sin and cos in terms of exponentials is similar to the definition of $L_x$ & $L_y$ in terms of raising & lowering operators?

How to estimate parameter functions of Sturm-Liouville operators using functional gradient descent?

Solving the heat equation in spherical polars with nonhomogeneous boundary conditions

Is Mercator projection an affine trasformation?

Shortcut to find imaginary part of analytic function given real part, without standard form of Cauchy-Riemann equations?

How to 2D Fourier Transform a chequerboard-like function by hand?

Poisson's equation-like formula in axis-symmetric Galactic potential in terms of Oort constants

Deriving the first moment of Collisionless Boltzmann Equation in Spherical Polar Coordinates

Calculation of Christoffel symbols of Schwarzschild metric using Lagrangian

How many independent connection coefficients are there for a given dimensional metric?

Is it special for a Lagrangian to equal its first integral?

How to take algebraic Bianchi identity into account when calculating the number of independent components of Riemann curvature tensor

Parametrized solution for motion of radially infalling object

How to find curve which I have the tangent vector field to in polar coordinates?

How to find the right combination of general solutions to fulfill nonhomogeneous boundary conditions when solving heat equation in spherical polars

How to interpret invariant subspaces in the definition of irreducible representation?

How to show that the gradient of a vector field is an order 2 tensor - and what can we learn from doing it wrong?

How can $(A \times \nabla) \times B$ be rearranged?

Do the free indices referring to the same dimension have to be denoted by the same letter on both sides of an expression when using Einstein notation?

Proof that $H \cap K$ is a group if $H$ and $K$ are subgroups of $G$ [duplicate]

Clarification of definition of quotient group - Does $Na, a \in G$ mean "cosets of $N$ in $G$"?

What property does the function hold which values equal the complex conjugate of the function with argument with opposite sign?$X(-\nu)=X^*(\nu)?$

Is there any matrix $A$ for which $A^{\dagger}A=AA^{\dagger}$ but $A\neq A^{\dagger}$?

How do I get the equality $\sum_{l-s}^{l+s}(2j+1) = (2l+1)(2s+1)?$