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

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Why speed of light is constant with respect to any inertial frame of reference? [duplicate]

Its getting too difficult to think.if we travel at the speed of light then will light will cross us at same speed or travel with us adjacent (special theory of relativity)
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34 views

Confirmation of a concept under General Relativity and Frames of Reference

I would like to preface this by saying that this isn't necessarily meant to be a full question, though it may become that, but it rather a confirmation of my understanding of a concept. Newton would ...
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22 views

Is mass relative? [duplicate]

This question has to do with the relativistic mass of an object. I have been reading that as energy increases, so does mass to a much lesser extent, and that this applies to kinetic energy as well. ...
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3answers
79 views

Length contraction in special relativity: can space be at rest in any frame?

Suppose a rod is moving at speed $v$ relative to me along its length. $L_0 = {}$length of the rod in the frame in which the rod is at rest $L = {}$length of the rod in my frame Then $$L = L_0 \sqrt{1-...
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64 views

Lorentz transformation: Can distance between two observers depend on the observers? [on hold]

Consider reference frames S and S'. S' is moving in positive x direction at speed v relative to S. Time measured by S is t and that measured by S' is t'. When t = 0, then t'= 0. Coordinate systems ...
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0answers
49 views

Imagine I'm on a spacecraft that was accelerated to 1.0$c$ could I only move backwards? [duplicate]

Imagine I'm in a sapcecraft1 that is moving with 1.0$c$ or at least is so close to that speed that a few miles per hour would just be left to reach $c$. So when I'm traveling now in the direction ...
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3answers
105 views

Why must $v$ be $< c$ in the Lorentz transformations? Do these equations not apply to light? [duplicate]

I was trying to understand how things look from the perspective of light. Looking at the Lorentz transformations, it seems that the universe would contract along the direction of movement into a plane,...
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1answer
89 views

If Speed is Relative can Absolute Acceleration be Real

This is , I suppose not a good question , but I think I am missing something which confuses me in this question. So my question is - Velocity is relative. So suppose a car is moving at a speed 200 ...
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2answers
116 views

All reference frame are inertial? Where is the flaw in reasoning?

This is my first post here. I have a line of thoughts which might be wrong but I couldn't find the error. Suppose we have a point mass subjected to an arbitrary force $F$. In the lab reference frame ...
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31 views

Dropping Objects on Whilst Moving Seen by an Outside Observer [closed]

As shown in the image, it seems obvious to me that the answer would be $D$. However, the answer is $C$. What is flawed in my conceptual understanding?
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63 views

Relativity - Twin Paradox and Absolute Frame of Reference - Why Not? [closed]

Absolute Reference Frame is a very discussed topic here and at other forums. For me it seems natural that the Relativity twin paradox should be explain in respect to such frame. The wikipedia article ...
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1answer
71 views

Speed of light from moving source evidence [closed]

The speed of light in a vacuum is taken to be a constant $c$ from a light source moving in our frame. What experiment(s) provide direct evidence for this. To what level of precision do we know this ?
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75 views

Why cannot Paul be the observer? (Questions about Twin Paradox)

Here is the explanation to the Twin Paradox in Feynman's Lecture on Physics 16–2. we consider a famous so-called “paradox” of Peter and Paul, who are supposed to be twins, born at the same time. ...
3
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1answer
75 views

What is physical meaning of Lorentz boost?

Physical meaning of spatial part of Lorentz transform is, obviously, rotations in R-space. Does anybody have a nice physical interpretation of boosts though? I can understand to some extent off-...
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4answers
95 views

Another Special Relativity Paradox inspired by Herbert Dingle's Paradox

Suppose spaceships A and B with clocks A and B move along the same straight line at uniform speeds differing by 161 miles per second. At the moment when B passes A, their clocks both read noon. ...
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1answer
120 views

Is conservation of momentum and energy valid for non-inertial frames?

Conservation laws of momentum and energy are said to be the most basic principles of physics. Are they also valid for non-inertial frames, and in what way?
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3answers
149 views

Interpretation of terms in the Lorentz Transformation

What is the physical significance of the term "${vx}/{c^2}$" in $$ t' = \gamma \left(t- \dfrac{vx}{c^2}\right) $$ It has got something to do with clock synchronization but cant derive the 'correction ...
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1answer
202 views

Herbert Dingle's paradox modified

Suppose two spaceships A and B have on them clocks A and B move along the same straight line at uniform speeds differing by 161 miles per second. And suppose they are at positions A and B in space ...
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1answer
62 views

If we traveled at almost the speed of light would objects appear the same?

We see objects with our eyes as object emits/reflects light. Say if we travel at almost the speed of light can we see the objects normally?
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2answers
126 views

Special Relativity: Verifying a general boost matrix is in the Lorentz group

I'm attempting the problem shown below. Using the hint, I have so far found: \begin{align}B^T \eta B &= \begin{pmatrix}\gamma & -\gamma\beta^j \\ -\gamma \beta_k & \delta_k^j+\frac{(\...
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1answer
20 views

Heliocentric to barycentric coordinates

I have a system with a central body and "particles" orbiting around it. The system is described in heliocentric coordinates. I am trying to obtain the velocity of the central body in barycentric ...
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0answers
38 views

A photon lives life as a flat-lander? [duplicate]

Think length contraction... I was thinking about going close to the speed of light the other day, and I was thinking about the idea that, if you went close to the speed of light, time would slow down ...
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2answers
92 views

Can't reach speed of light, but relative to who?

Imagine a stationary person (with respect to a spaceship) floating in space and looks at a clock on the spaceship going 0.5c and sees it's clock ticking slower than his own, and concludes that it is ...
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1answer
44 views

Why would two inertial frames be distinguishable, if the coordinate of an event perpendicular to the motion would be different? [closed]

This question arises from the classical example: imagine a laboratory frame, and a space shuttle frame, the space shuttle moving in the laboratory frame with a constant velocity, let's say in the $x$ ...
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2answers
100 views

Will accelerated observer see radiation from the charge that is at rest in observers's frame?

So I had a huge debate about this with my friends. Imagine that you are in a non-inertial frame of reference. For simplicity, assume that frame is accelerated along x-axis. You have held a charge in ...
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1answer
50 views

Relativistic transformation of electrical current [closed]

If, in frame $S$, we have an electrically neutral wire with some current $I$, modelled as positive charges moving in $x$ direction and negative charges moving in $-x$ direction, then how would one ...
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28 views

How to prove that the Einstein velocity addition is a one-parameter composition formula of a one parameter group? [duplicate]

How to prove that the Einstein velocity addition is a one-parameter composition formula of a one parameter group?
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5answers
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Is it possible to stay up while riding a bike on a moving sidewalk without actually moving?

If I ride a bicycle on a moving sidewalk so that I am not in effect moving at all relative to the ground, will I fall over?
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83 views

The path that a light beam takes in empty space

First excuse me if this question is very simple for you but for me and for my friend is not. Recently we were discussing what path a light beam will follow in a box moving at a constant velocity in ...
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1answer
41 views

Time variable in Lorentz transformations

When an object goes with a speed near from the light celerity, it inflates in the direction of its speed. The inflation rate is given by Lorentz transformations as follows: $x'= γ(x-vt)$ where $v$ ...
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1answer
86 views

Derivation of Lorentz Transformations

How can I derive the Lorentz transformations? I don't want to use hyperbolic functions and the fact that the light waves travel by forming spherical wavefronts. Is there a way to derive the Lorentz ...
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2answers
89 views

How can we know that the speed of light is constant?

Science say that within a constant time frame the light travels a constant distance. But if time is relative how can it be possible to use it as a reference to say that something is constant?
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28 views

Is it true that the free body cannot remain at rest in inhomogeneous and anisotropic space?

In the page 5 of which Mechanics by written L.D.Landau, this book said "If we were to choose an arbitrary frame of reference, space would be in-homogeneous and an-isotropic. This means that, even if a ...
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2answers
228 views

How is 4-current a 4-vector?

I am looking at Jackson sec 11.9, where he states that the $\rho,\bf{J}$ form the 4-current $$J^\alpha=(c\rho,\bf{J})$$ Jackson says this is from the invariant of the 4-divergence $\partial^\alpha ...
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2answers
119 views

How to interpret Hermann Minkowski's comments on the construction of spacetime

What did Minkowski mean by his statement: "The views of space and time which I wish to lay before you have sprung from the soil of experimental physics, and therein lies their strength. They are ...
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2answers
95 views

Why does Special Relativity apply to more than just light?

It is my understanding that time dilation is derived from the constancy of the speed of light in vacuum. I would assume this implies that the quirky consequences would therefore apply only to light. ...
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2answers
58 views

Pole and Barn Paradox w/ Spacetime Interval

I'm having trouble with a pole and barn paradox problem. The problem is as follows: A pole vaulter is running with a pole at $ v=\frac{\sqrt3}{2}c $. Her pole has a proper length of $L$. She runs ...
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1answer
50 views

Does curved spacetime arise from inhomogeneity of gravitational field?

In general relativity textbooks such as Sean Carroll's Spacetime and Geometry, there is often a line of reasoning that goes like this: Strong equivalence principle states that free falling frames ...
3
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1answer
80 views

Homogeneity and isotropy and derivation of the Lorentz transformations

In deriving the Lorentz transformations I have found (from reading a few different sets lecture notes) that it is argued that they must be linear and thus there general form must be $$x'=Ax+Bt,\quad t'...
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31 views

Inertial coordinate systems [duplicate]

In Newtonian mechanics, by the following two assumptions: (i) The time is absolute. (ii) The length is absolute. it is easy find the relations betweem two coordinate systems with uniform motion ...
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2answers
76 views

Definition of the Lorentz transformations [closed]

Until very recently I believed that the Lorentz transformations were defined as "the transformations that carry one inertial reference frame into another". In Wikipedia's page we find something along ...
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1answer
47 views

An example of a theory that respects the Weak Equivalence Principle but violates the Einstein Equivalence Principle

The Weak Equivalence Principle has any one of the following forms: the inertial mass is equal to the gravitational mass there exists a preferred class of trajectories through spacetime, known as ...
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1answer
31 views

Newton's 2nd law for rotation (accelerated rolling and inertial frame of reference) [duplicate]

I need help in understanding why, in accelerated rolling, the center of mass must be at the origin of an inertial frame of reference in order for the second law to be applicable. Thanks!
4
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2answers
115 views

Two inertial frames (different angles)

The motion of the earth relative to a star changes the angle at which the star is perceived. Consider to inertial frames of reference I and I'. I' moves with velocity w relative to I along the x-axis. ...
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1answer
37 views

Coordinate Transformation in Classical Mechanics

The coordinates in one inertial frame are represented by $(x,t)$. Under coordinate transformation, the coordinates in another inertial frame can be represented by $f(x(t),t)$. It can be shown that the ...
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2answers
54 views

Does the constancy of the speed of light in vacuum hold for any observer in GR as well?

From SR, we know that the speed of light in a vacuum is the same for all observers, regardless of the motion of the light source. But in GR, does it still hold for all observers? I mean the constancy ...
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21 views

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 ...
2
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2answers
78 views

Twin paradox in special relativity: length contraction

Can the concept of twin paradox be applied to length contraction as well? meaning that the twin which is in spaceship will have its meter rod "actually" contracted while he will see his brother's ...
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1answer
55 views

Which reference frame decides the relative velocity of two reference frames?

The following thought experiment is often used to introduce Special Relativity: The thought experiment fails to specify which reference frame establishes $\vec{v}$--the observer on earth or the ...