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The following questions (in no particular order) which I had submitted have been "Deleted by Community":

2. Is average speed an invariant?

Is the value of average speed an invariant?,
specificly the value of the average speed, with respect to suitable(1) specific participants, say $P$ and $Q$, of some specific participant, say $A$, as $A$ moved from $P$ and $Q$?

Expressing the value of the average speed of $A$ wrt. $P$ and $Q$ as

$$v_{PQ}[~A~] := c~\beta_{PQ}[~A~],$$

where $c$ denotes the signal front speed, and $\beta_{PQ}[~A~]$ is a specific real number,
and where the average refers to the trial from $P$ and $A$ having departed from each other until $P$ and $A$ having reached each other,
does the value of $\beta_{PQ}[~A~]$ depend on the assignment of coordinate values to the relevant unique events $\varepsilon_{AP}$ and $\varepsilon_{AQ}$ (and/or to other events)?

Does the real-number value $\beta_{PQ}[~A~]$ change if coordinate values which are assigned to event $\varepsilon_{AP}$ are being changed, or if coordinate values which are assigned to event $\varepsilon_{AQ}$ are being changed?

Note also, that the real-number value $\beta_{PQ}[~A~]$ can be expressed in terms of intervals "between" certain pairs of the relevant events, e.g.

$$\beta_{PQ}[~A~] = \frac{s^2[~\varepsilon_{AP}, \varepsilon_{AQ}~] - s^2[~\varepsilon_{FQ}, \varepsilon_{AQ}~]}{s^2[~\varepsilon_{AP}, \varepsilon_{AQ}~] + s^2[~\varepsilon_{FQ}, \varepsilon_{AQ}~]},$$

where event $\varepsilon_{FQ}$ denotes the (unique) event of the future ("forward") light cone of event $\varepsilon_{AP}$ in which $Q$ took part (in coincidence with some suitable participant $F$); and that (presumably) the values of intervals are invariant.

(1: Specifily, $P$ and $Q$ remaining separate and at rest with respect to each other; i.e. constituting members of an inertial system in the sense of Rindler: "simply an infinite set of point particles sitting still in space relative to each other".)


2d
revised What's the physical meaning of a “sphere”, and a pair (or even a series) of “concentric spheres”, in a region with Schwarzschild geometry?
(v3.141592: Footnote to specify the meaning of "physical meaning" in the context of [tag:general-relativity].)
Jul
30
revised Angle sum of triangle in Schwarzschild solution
corrected spelling the name of K. Schwarzschild (also in the title);cmp. https://en.wikipedia.org/w/index.php?title=Schwarzschild_Solution
Jul
27
revised How to derive the Schwarzschild metric?
corrected spelling the name of K. Schwarzschild; cmp. https://en.wikipedia.org/wiki/Schwarzschild_metric
Jul
27
revised Schwarzschild Solution
corrected spelling the name of K. Schwarzschild (in the title); cmp. https://en.wikipedia.org/wiki/Schwarzschild_metric
Jul
27
revised Curvature based derivation of Schwarzschild Metric
corrected spelling the name of K. Schwarzschild; cmp. the link which was already present in the OP
Jul
27
revised Is momentum an invariant?
(v3.1: referring specificly to the sense of the word "invariant" as used in the theory of relativity.)
Jul
27
revised Is momentum an invariant?
(v3.14159: capitalization still matters!)
Jul
24
revised Angle between two momenta in particle physics (principal axis of a two-body decay vs. center-of-mass motion in the lab)
suggested an expansion of the title to make it more descriptive and specific. Also: some gentle copy-editing
Jul
24
revised Angle between two momenta in particle physics (principal axis of a two-body decay vs. center-of-mass motion in the lab)
(v3.14159265: a bit neater, still ...)
Jul
23
revised Angle between two momenta in particle physics (principal axis of a two-body decay vs. center-of-mass motion in the lab)
(v3.1415926: matching squares, instead of square root)
Jul
23
revised Angle between two momenta in particle physics (principal axis of a two-body decay vs. center-of-mass motion in the lab)
(v3.141592: replaced incorrect dot multiplication by plain scalar multiplication; rearranging terms suitably. Also some additional formatting.)
Jul
23
revised Angle between two momenta in particle physics (principal axis of a two-body decay vs. center-of-mass motion in the lab)
(v3.14159: copy-editing.)
Jul
23
revised How to achieve vertical lift using magnets
title modified; copy editing
Jul
16
revised Why do we use Mie scattering to describe light scattering off large objects?
spelling corrected
Jul
9
revised Two apparent contradictions in SR involving time dilation and length contraction
(v3.1415: more copy-editing)
Jul
9
revised Two apparent contradictions in SR involving time dilation and length contraction
(v3.141: corrected/inverted duration ratio; and some copy-editing)
Jul
4
revised Simple Harmonic Motion in Special Relativity
(v3.141592: mistaken minus-sign removed.)
Jul
3
revised Must the product of the two complementary quantities in an uncertainty relation have unit $\text{Js}$?
Expressed the Uncertainty Principle (also) as **in**equality; and corrected spelling the surname of M. Planck.
Jul
3
revised Must the product of the two complementary quantities in an uncertainty relation have unit $\text{Js}$?
corrected an omission (exponent) and minor spelling
Jul
2
revised Accuracy and Error of Atomic Clocks
some corrections and copy-editing