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

learn more… | top users | synonyms

1
vote
2answers
54 views

velocity bigger than light?

We know, according relativity theory, no information or matter can travel with velocity bigger than light. However, consider the following situation: a completely empty water hose is hypothetically ...
0
votes
0answers
18 views

How do I start studying astrophysics and it's relations with relativity?

I am a high school student who's very interested in astrophysics and the whole idea that space time is infact a fabric rather than nothing. Unfortunately, my school teaches no where near to any of ...
0
votes
1answer
31 views

Exercise 18b in Schutz's First course in GR

The question is as follows: Show that a timelike vector and a null vector cannot be orthogonal. So we have a timelike vector $\vec{A}$, s.t $\vec{A}^2<0$; and a null vector, $\vec{B}$ s.t ...
0
votes
4answers
50 views

Are there any known non-zero mass objects travelling at almost $c$ observed in the universe so far?

Have we ever observed a body or particle with non zero mass traveling at almost $c$? I'm asking this because according to relativity as an object approaches light speed it's mass approaches infinity, ...
1
vote
0answers
43 views

Are objects like $a^{\mu \nu} a_{\mu \nu} b^{\mu \nu}$ consistent with Einstein summation?

I'm familiar with Einstein' summation notation and I understand objects like $a^{\mu \nu} a_{\mu \nu}$ just fine. But I'm wondering why I've never come across objects like this: $a^{\mu \nu} a_{\mu ...
1
vote
0answers
27 views

Classical Quantum or Relativistic? [on hold]

An ensemble contains free electrons at 10^3 electrons per m^3 at 10^7 K. What can this ensemble be treated as: a Classical Quantum or Relativistic gas or in some overlapping domain?
1
vote
1answer
59 views

Michelson Morley experiment - why is there an interference pattern in the first place?

In descriptions of the experiment, the two arms of the interferometer have the same length. There's an interference pattern which was expected to be shifted when the system was rotated 90 degrees. But ...
1
vote
0answers
38 views

What is a Geodetic?

What is a geodetic? First I thought it was a typo (hehehe..). To me, the term "geodetic" is used to describe a curve that belongs to a congruence of geodesics...but, I also think I'm wrong. ...
0
votes
1answer
44 views

When travelling in the direction of light, what is my relative velocity?

If suppose I am traveling in the same direction as that of light, the relative velocity I am traveling with is speed of light + my speed in the direction of light. Is this correct? Does this have ...
1
vote
1answer
47 views

Is light relative? [duplicate]

I was wondering, if two cars (A and B) are going at different velocities let's say A=90km/h, B=80km/h then if we add the two speeds we get 170km/h meaning they are relative to each other. But if one ...
1
vote
0answers
31 views

Relativity Mapmaking in spacetime [closed]

The problem as stated: I do not know how I am supposed to map this. The instructions don't make sense to me and the textbook is really un-helpful. This is the map that I have to draw this on. I ...
0
votes
0answers
35 views

Does a photon arrive at the time it was emitted [duplicate]

I was thinking about the implications of time dilation and wondering if it has an effect on photons. Obviously a photon doesn't age. But is there any other effects on a photon traveling massive ...
0
votes
1answer
110 views

When will Einstein's theories become laws? [closed]

Einstein theories , specifically relativity, have been fascinating us for around 100 years yet with all the real and actual evidence of its validity we still consider it a "theory"..... How much more ...
1
vote
0answers
22 views

Topic on relativistic celestial mechanics [closed]

I have to do a small 10-15 minutes presentation about celestial mechanics, and I am searching for a topic. As a mathematician my background in physics is not very extensive, but I have some notions ...
0
votes
2answers
159 views

Does relativity violate uncertainty principle?

Let us say I sit on an electron. According to me the electron is at rest. Also, I will know the position of the electron accurately as I can take the electron as the origin. So, I know both position ...
2
votes
3answers
119 views

Is gravity Lorentz-invariant?

If I go whizzing past the Sun in my spaceship at 0.8c, I will see that the Sun looks like it has been squished. That is, it will be Lorentz-contracted along the direction of my motion (by a factor of ...
0
votes
1answer
39 views

Is the matrix representation of the Lorentz transform the same for all 4-vectors?

If I have a four vector of the form: $$ \left( \begin{array}{ccc} T\\ \vec{X}\end{array} \right) $$ where $T$ is the analogous time component (i.e. energy, angular frequency, scalar potential, charge ...
2
votes
2answers
70 views

What happens during mass-energy conversion

A mass is another form of energy. When a mass ceases to exist as 'matter', it exists as energy - in the forms of energy we generally know ( light,heat ). But is this so simple? When a mass exists in ...
3
votes
6answers
253 views

Could the universe be accurately simulated with an infinitely powerful computer? [duplicate]

This would mean that every event happens because of what has hapened before it and there is no randomness factor. At a microscopic level, the motion of atoms is a result of the motion of other atoms ...
1
vote
0answers
28 views

Energy of a relativist electron [closed]

I need to find a way to obtain $E = mc^2(\gamma -1)$ by starting with : $E = mc \cdot p = mc \cdot v \cdot \gamma$ with $ \gamma = \frac {1}{\sqrt{1-\frac{v^2}{c^2}}}$
1
vote
0answers
72 views

Faster than the speed of light? [closed]

Just a conceptual question here. I have read that this is impossible as nothing can travel faster than light. But if an observer were travelling faster than the speed of light from a particular point ...
0
votes
0answers
29 views

Reference request for relativistic imaging

Being a high-school physics teacher, I always am searching for compelling and different approaches to the subject. In the case of (special) relativity a frequent curiosity arises while discussing what ...
3
votes
2answers
128 views

Why time slows only for moving object and not stationary observer? How the “stationary” & “moving” are decided? [duplicate]

Explanation for the questions in the title: According to the the (special theory of) Relativity, if an observer is stationary and sees a fast moving object then time runs faster for the observer ...
-1
votes
3answers
69 views

Are all conserved scalars proportional to relativistic mass? [closed]

I have read in Rindler's relativity book that all scalars depend only on the magnitude of velocity of a particle and that are conserved are proportional to relativistic mass. ...
2
votes
2answers
100 views

Particle accelerators reaching light speed [duplicate]

I just have a question in mind that's stuck in my head, and it's why particle accelerators cannot accelerate any particle to the speed of light. I'm assuming it involves Einstien's theory of ...
0
votes
2answers
105 views

Stripped twin paradox [closed]

Consider an empty space, except for Alice and Bob. Suppose Alice sees Bob move away and then come back again. Suppose Bob sees Alice move away and then come back again. Suppose either of them will ...
1
vote
2answers
70 views

Can the single object accelerate? (Relativity theory) [closed]

Suppose space is empty except for one single object. According to relativity theory it doesn't matter whether we assign a constant velocity to it or not; in both scenarios the same is predicted. The ...
0
votes
1answer
52 views

Magnetic field existence - a relativistic approach

Recently I learnt that magnetic force is equal to relativistic electrostatic force. With this approach I was able to understand the motion of a charged particle kept near a current carrying conductor. ...
0
votes
0answers
16 views

if a meteorite is moving in space fast enough to generate a lot of mass shouldn't it generate gravity because its moving? [duplicate]

is it how planets form when is happens to have alot of mass to generate a little bit of gravity, oh and bullets for example they generate mass when moving and causes it generate mass?
2
votes
1answer
53 views

Relativity of simultaneity subtle example [closed]

imagine three persons, Person A is standing next to a device these device is an AND gate if two photons(one from right and one from left) reaches the AND gate at the same time the device explodes and ...
1
vote
3answers
204 views

How can the past, the present and the future coexist at the same time? [closed]

We all heard it many times, the theory of Time suggest it is parallel rather than being linear. This leaves the door opened for alternate realities and well, immortality. However, even after reading ...
2
votes
0answers
53 views

Are gravitational waves constrained by special relativity (speed of light)? [duplicate]

In Lawrence Krauss's excellent book "Universe from Nothing" and his related lectures, he cites findings of the BOOMERANG-instrument observations in Anarctica as used to measure the diameter of ...
0
votes
1answer
52 views

How can I properly learn relativity with an electrical engineering background? [closed]

I want to properly learn the theory of relativity, purely for self-interest. When I say relativity, I mean both flavours: special and general. Are there any good books which go into both the ...
1
vote
0answers
29 views

Getting an object to travel at or near light speed by adding velocities [duplicate]

Firstly I'll just give a brief example of where my query came from. I was watching the episode of Futurama where Bender meets God after being fired from the planet express ships torpedo tube. The crew ...
1
vote
0answers
17 views

Basic Special Relativity Problem [closed]

A cylindrical rocket 10 m long and 2 m in diameter moves at a speed $ V=0.9c $ with respect to earth, where $c$ is the speed of light in vacuum. I. Knowing that the pilot's heart beats 70 times per ...
0
votes
0answers
27 views

Real and relative velocity formula

What i need is a thing more complicated than the usual relative velocity formula. Imagine a radar. You are at the center, moving at some angle, but lets make it clear, you are always at the center. ...
0
votes
1answer
120 views

F=ma is true in an accelerating coordinate system [closed]

There are plenty of similar topics about the physical or intuitive meaning of the equivalence principle or statement such as ''laws of physics are true in every frame of reference''. Usually answers ...
0
votes
2answers
51 views

Double the mass in the universe, double the inertia

If I double (halve) the mass in the visible universe, will my inertia double (halve)? I think it should, at least as soon ''I have received the news of this doubling''. But what does the General ...
4
votes
1answer
53 views

Would a star be observed to burn brighter traveling at relativistic speeds?

Would a star, similar to our own, be observed to "burn" differently at relativistic speeds? I am only thinking this because the observed relativistic mass would change.
-1
votes
1answer
71 views

Can you break causality if you are able to instantaneously perceive a distant system? [closed]

It is known that relativity plus FTL communication implies violation of causality, but now I propose the following thought experiment: Suppose that you have a magical spyglass that can be used to ...
3
votes
0answers
87 views

Why Use the Non-Relativistic Momentum Operator in Relativistic Quantum Mechanics?

In deriving the Klein Gordon equation one starts out with the relativistic energy relation E^2 = p^2 + m^2 and substitutes the quantum momentum operator that corresponds to non-relativistic QM, p = -i ...
1
vote
0answers
42 views

Reading about how Einstein ended up with GR [closed]

I would like to learn about the road that Einstein's train-of-thought traveled from special relativity to general :). I am also interested in dead ends and stuff. Can someone recommend articles, ...
0
votes
0answers
34 views

Stress-Energy Tensor of Riemann's Curvature Field

Einstein, in "The Foundation of the General Theory of Relativity," as well as most modern lecturers in the subject, use a pseudo-tensor for the stress-energy of the gravitational field. By ...
0
votes
0answers
32 views

Charged Universe and charge-dependent inertia/anti-inertia

I posted this same question as a follow up for the main question here. I expected to get a quick answer but since none have come up I raise it as a topic in its own right. So the question is: Suppose ...
0
votes
1answer
92 views

Relativistic explanation of Radiation

I ask this question again in a simpler, shorter form. Maxwell's equations can be derived with Special relativity starting from the Coulomb's law. Therefore all the phenomena of classical ...
1
vote
0answers
45 views

What would happen, gravitationally, to ships passing by each other at high speeds vs high accelerations?

Consider this scenario: Two identical space ships, the SS Observer and the SS Accelerator. In scenario A, the SS Accelerator is accelerated up to near C, stops accelerating, then flies past the SS ...
0
votes
0answers
26 views

What would be seen if a firing laser is accelerated to relativistic speeds then back?

Consider this scenario: Two identical space ships, the SS Observer and the SS Accelerator. Each ship is spherical with a band of mirrored material around the outside and contains a green laser. They ...
0
votes
0answers
45 views

The Inertial theory of Sciama and an electromagnetic analogue

In 1952 D. W. Sciama introduced a paper On the origin of inertia. It presents a method in which inertia could arise from other mass in the universe. It goes along these lines: If you try to ...
0
votes
1answer
49 views

Relative speed of Geostationary satellite with respect to earth?

I was wondering whether relative speed of geostationary satellite with respect to earth is zero or not.Since angular velocity of satellite about earth is same as angular speed of earth about its own ...
2
votes
1answer
57 views

Is there a gravitational radiation reaction force?

As you may know, the linearized relativity theory (or gravitoelectromagnetism), obeys equations analogous to Maxwell's equations in electrodynamics. These equations in ED result in the troubling ...