Tagged Questions

A specific reference frame that describes its coordinates in a manner that does not depend on time and is isotropic.

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Static model of the Earth motion

Believe it or not, an old man I know in 2015 still negates the Earth orbital motion around the Sun. He believes the earth is rotating on itself and acknowledges this gives day and night on every ...
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Shape and even connectedness of accelerating components in SR is frame dependent?

In some inertial frame consider a disk of radius 1 lightyear at rest. Then along the edge of the disk there are some people in spacesuits at rest hovering right above the disk (which has negligible ...
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Electromagnetic Tensor under Lorentz transformation, $F'(\Lambda x)= \Lambda F(x) \Lambda^T$?)

Suppose we have a configuration of electric and magnetic fields $E(x1,x2,x3,x4)$ and $B(x1,x2,x3,x4)$, they depend of position and time for a fixed coordinate system. And I want to know how someone in ...
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Is there an absolute accelerated frame of reference?

I know from special relativity and from a little common sense that there is no absolute inertial frame of reference; that is, physics acts the same no matter what velocity you go at. However, that ...
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How to add together non-parallel rapidities?

How to add together non-parallel rapidities? The Lorentz transformation is essentially a hyperbolic rotation, which rotation can be described by a hyperbolic angle, which is called the rapidity. I ...
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Space and time variant? But together invariant?

I admit I'm having difficulty with spacetime. I don't understand how unifying space and time, seemingly variant quantities, results in an invariant spacetime. All texts and references talk about using ...
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Gallilean Transformations with Linear Acceleration

I'm wondering if it is possible at all to use Galilean transformations to simplify this problem. Consider two massive objects (Objects A and B) in space. The two objects are attached via a spring ...
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Derive Galilean transformation. (The meaning of the relativity)

In the book The meaning of the relativity Einstein says that in classic mechanics two postulates are previously supposed: 1.- The time is absolute. 2.- The longitude is absolute. And this implies ...
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Value of $E_x$ through an $X-\textrm{boost}$

Suppose I'm standing at the (0,0,0) point of a coordinate system and I see an electric field where $E_x=f(t,x,y,z)=\sin(x\cdot y\cdot z\cdot t)$ and at time $t_0=0$ I start moving on the x-axis at ...
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Relativity of simultaneity: light source inside and outside

(Orange are light sources and red are observers) There is a train, which is moving right. In each side, there is a light source, which emits light when the train passes certain point on a track. And ...
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Simple Rotating frame of reference

I have a car moving in straight line with certain time-varying acceleration and there is another car moving in a curvilinear way along some curved path with some time-varying acceleration. The ...
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Can an event occur before or after the other one depending on what frame of reference we are in?

Two buses moving relative to each other with 30% the speed of light (4 light-min apart). Now by some mysterious way bus 1 comes to the knowledge that after 3 min-bus 2 time bus 2 is going to explode. ...
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3-body system centre of mass

I have a three body system of point masses that represent mercury, earth and the sun. I want them to orbit about a common centre of mass, but I think the centre of mass will move. I need the centre of ...
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How would you prove/verify that the real forces are independent of frame of reference?

How would you prove/verify that the real forces are independent of frame of reference?
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Absoluteness of Simultaneity?

Here is a very good proof that simultaneity is absolute, not relative. The question: Is this proof wrong, or is Einstein? Can you prove it? What is the mistake in the proof, if any? If there is none, ...
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Forward and Behind Frames of Reference

It's my understanding that light travels at the same speed in all inertial frames of reference. Suppose there's a small train car 5 feet long (at our rest point of view) traveling at a constant speed ...
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Light cones and reference frames

I'd like to know what does it mean exactly to find a reference frame in which two events occur at the same time or in the same space coordinates. As I picture it if we have two events A and B in a (x, ...