General Relativity 2025

Question 1

What does the covariant derivative take into account?

Accepted Answer

Correction terms which quantify how the coordinate basis changes

Question 2

Which metric for Black Holes does one want to use to look at causality?

Accepted Answer

Kurskal-Szekeres, Eddington-Finkelstein

Question 3

Spacetime is a...

Accepted Answer

...manifold

Question 4

"I have heard enough about cats"

Accepted Answer

That poor cat..., Yes! Please, fall into the black hole, you stupid cat., What cat?!, No, forever a cat lover.

Question 5

Curvature can quantify the...

Accepted Answer

geometry of spacetime, gravitational tidal field

Question 6

What is true? The Einstein Tensor vanishes...

Accepted Answer

if spacetime is Minkowski, if the Riemann tensor vanishes everywhere, for vacuum solutions of the EFE, when spacetime is Ricci flat, meaning no energy-matter content

Question 7

The Lie derivative describes how...

Accepted Answer

tensors change under transformation of the manifold

Question 8

A static spacetime is automatically stationary

Accepted Answer

True

Question 9

The Schwarzschild solution is/has a...

Accepted Answer

spherically symmetric, vacuum solution, unique solution, static

Question 10

"The components of the torsion are zero" is equivalent to "The connection is symmetric in its lower indices"

Accepted Answer

True

Question 11

In GR the motion of a freely-falling particle can be described by the...

Accepted Answer

Geodesic equation, Euler-Lagrange equation

Question 12

What does Birkhoff's theorem state?

Accepted Answer

Every spherically symmetric vacuum solution is static and asympt. flat, The Schwarzschild metric is the unique black hole solution

Question 13

What does diffeomorphism invariance mean in GR?

Accepted Answer

Physical quantities are invariant under smooth coordinate transformations

Question 14

Which of the following transform as tensors?

Accepted Answer

The Ricci Scalar, The curvature

Question 15

What is true?

Accepted Answer

Only static spacetimes are invariant under time inversion, In static spacetime the timelike KVF is orthogonal to spatial surfaces

Question 16

Killing vectors...

Accepted Answer

generate symmetry transformations of the metric, generate symmetry trafos of all tensors constructed only from metric, generate symmetry transformations of the curvature tensor

Question 17

abla_{\mu}T^{\mu
u}=0 means that the energy is conserved...

Accepted Answer

locally

Question 18

Astronauts reaching the ergosphere of a Kerr black hole...

Accepted Answer

cannot remain at rest w.r.t. distant observers

Question 19

What is the gravitational field described by?

Accepted Answer

Christoffel Symbols

Question 20

What is the Einstein Equivalence Principle?

Accepted Answer

One can always do a transform. such that the metric is locally Minkowskian, Locally a uniform acceleration and a uniform grav. field are the same

Question 21

The Einstein tensor appears in Einstein's field equations instead of the Ricci tensor because...

Accepted Answer

it complies with local energy-momentum conservation, of the contracted Bianchi identity

Question 22

What does the equation of geodesic deviation describe?

Accepted Answer

How the separation between neighboring geodesics evolves due to curvature, How tidal forces cause relative acceleration between nearby FF particles

General Relativity 2025

Questions 22

General Relativity 2025

Questions 22