The union of special (SR) and general (GR) relativity. Use this tag if both SR and GR apply.

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Principle of locality and forces

I have a silly confusion about the statement written in the link Einstein and Locality ''external influence on A has no direct influence on B; this is known as the Principle of Local Action.'' ...
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103 views

The relativistic mechanics of a battery that is being charged and accelerated at the same time

This might be an interesting question: Let's attach a battery into one end of an electric cable. Then we rotate the battery around, with accelerating speed, using 100 Watts of power, while the ...
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126 views

Energy-Momentum Tensor under Lorentz Transformation

In relativity, the symmetric energy-momentum tensor is given by $$ T^{ij}, $$ where $T^{00}$ is the energy density and $\frac{1}{c}T^{10}$ is the momentum density. Thus: $$ \left(\frac{1}{c}T^{00}dV, ...
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403 views

Ephemeris calculations: Light time correction of the moon

I am currently trying to calculate apparent positions from raw JPL data. I've got it pretty much figured out, but there is one thing that's bugging me: Has the light time correction of the moon to be ...
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48 views

Is the charge of a current carrying wire real or hypothetical?

Realist753 Theory Relativistic Electrodynamics assert that a current carrying wire being neutral in a laboratory frame of reference appears electrostatically charged to an observer in relative ...
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68 views

Time inversion for Euler equation

Consider Euler equation for continuum body: $$\frac{\partial u^i}{\partial t}+\mathbf u\cdot \nabla u^i=- \frac{1}{\rho} \frac{\partial p}{\partial x^i} $$ where $\rho$ is the mass density, $p$ is ...
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61 views

Is the cross section of a relativistic water hose or string always a perfect circle?

Given is a very long tube, such as a water hose or a tubular string with finite thickness, that has a constant circular cross section of radius $r$ along the length and that is at rest in an inertial ...
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36 views

How do we generalize limitations on the propagation speed of sinusoidal waves to limitations for transmitting any kind of information?

Our calculations on EM waves basically deal with harmonic waves and through such calculations and relations, we derive some relations and limitations for wave like phenomena. Of these relations are ...
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108 views

How to name different approaches to relativistic quantum theory

In the introductory chapter of the QFT book by Mark Srednicki the author notes that [p. 26] So now we have two different approaches to relativistic quantum theory [...] Which [one of those two] we ...
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163 views

How do I extend the Lorentz transformation metric to dimensions>4?

How do I extend the general Lorentz transformation matrix (not just a boost along an axis, but in directions where the dx1/dt, dx2/dt, dx3/dt, components are all not zero. For eg. as on the Wikipedia ...
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91 views

Relativistic beaming - which power of the Doppler factor

The context is that I'm building a simulation of a starfield, as seen from a relativistic spaceship. (EDIT: the simulation can now be found here.) One reference that I'm using is this paper by John ...
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89 views

What is Einstein regarding as the problem of physical relativity in his lecture of 1923?

The following is the extract from Albert Einstein's lecture to the Nordic Assembly of Naturalists (July 11, 1923). If we consider that part of the theory of relativity which may nowadays in a ...
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41 views

Accelerated charge in relativistic frame

An accelerated charge radiates energy as electromagnetic waves. Imagine a point charge at rest in an inertial frame We are standing on a frame accelerating with respect to the charge. Now with respect ...
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137 views

Mercury's Orbital Precession in Special Relativity

I am researching Mercury's orbital precession. I have considered most perturbations and general relativity. I am still not satisfied. I need your help. I need a solution to Exercise 13, Chapter 6, in ...
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47 views

Conditions that the coordinate must satisfy in order to become local inertial

Consider the coordinate transformation $$ \tilde x^a=x^a+\frac{1}{2}\Gamma^a_{bc}x^bx^c $$ I have shown that at the origin $O=(0,0,0,0)$, $$ \frac{\partial\tilde g_{ab}}{\partial\tilde x^c}=0 $$ ...
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(Special Relativity) Points that can be seen by an observer

Let the metric be $$ ds^2=(1+gz)^2dt^2-dx^2-dy^2-dz^2 $$ where $g$ is a positive constant. Let an observer be stationary at $x=y=0$ on the surface $z=0$ and look upwards at an angle $\theta$, how ...
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10 views

When High-Speed Traveler is On Differently-Shaped Surface Compared to Observer, What Does Observer See When He/She Goes Around Corner?

As stated in my other question, the length of a traveler going at relativistic speeds compared to an observer only gets contracted in a single direction, i.e. the direction of motion. Well, what ...
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37 views

Relative effects of forces

Excuse me for my ignorance but I really couldn't find a solution. According to Einstein, every happening is possible to describe by both of interacted objects. Is there any other way to describe the ...
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29 views

Velocity in a pseudo-Riemannian manifold

Suppose we have a pseudo-Riemannian manifold (modeled by $\mathbb R^{p,q}$) with signature $$(\underbrace{+,+,\cdots,+}_p,\underbrace{-,-,\cdots,-}_q)$$ Meaning we have $q$ spacelike dimensions and ...
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62 views

How to move from Special to General Relativity

I have understood special relativity nicely, and right now I am trying to learn general relativity from D'Inverno's book. I an finding it rather difficult to understand the pre-requisite math (i.e. ...
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29 views

concept of density in gravitational lensing

I may just be being very dense (no pun intended) but i'm reading up on gravitational lensing and it seems to require a notion of density (e.g. see here) I'm working on a question involving light ...
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82 views

At near light speeds, are small objects in your path a problem?

A mental exercise: A space ship is accelerating toward me from far away. As it approaches me, I can observe its acceleration. This high speed ship keeps accelerating faster toward the speed of light. ...
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85 views

force on two particles moving with same velocity

When two charged particles having same charge $q$ are at rest, only electric force acts upon it: a repulsive force of magnitude $\frac{kq^2}{r^2}.$ Now let them move with a constant velocity ...
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67 views

Need help with relativistic dynamics

I understand the concept, but I'm having a hard time applying the consequences of conservation (energy/momentum). For example: A proton with kinetic energy 437 MeV hits a proton at rest elastically ...
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22 views

Period of Transmission of signals in different frames

A radar transmitter (T) is fixed to a system $S_{2}$ which is moving to the right with speed v relative to system $S_{1}$. A timer in $S_{2}$, having a period $\tau_{0}$ (measured in $S_{2}$) causes ...