All Questions
13
questions
-2
votes
1
answer
65
views
Lorentz transform causes Faster than light motion for Spacelike-separated object?
Consider a 5-meter rod which exists on the x-axis of a frame of reference:
Now consider an observer moving at a velocity $0.1c$ relative to this reference frame, from right to left. Their frame of ...
0
votes
0
answers
51
views
Geometric definition absolute velocity in affine spaces
currently I am reading the following paper by Halvorson and Clifton (https://arxiv.org/abs/quant-ph/0103041) where they try to argue that localizable particles are inconsistent with relativistic ...
- 21
2
votes
0
answers
179
views
An interpretation of special relativity? [closed]
Consider a 4-dimensional space $\mathrm{S}$ in which all objects move at the same speed $c_S$ but in different directions. For the objects A and B that move in directions $\overrightarrow{u_A}$ and $\...
- 21
0
votes
4
answers
184
views
Spaceships with relativistic instruments
I wonder if it is possible, for future spaceships, to have somekind of instruments on board, that will tell the pilot what his true speed through spacetime is and how much time dilation he is ...
- 107
3
votes
2
answers
702
views
Proper time and 4-velocity
Now, 4-velocity is defined as $\mathbf u^\mu$ = $dx^\mu/d\tau$, $\tau$ being the proper time.
And then the four momenta is $\mathbf P^\mu$= $m_0$$\mathbf u^\mu$.
My doubt is, suppose we have two ...
- 453
0
votes
4
answers
129
views
Observed Behavior of Light When Relative Motion $> c$
I am trying to wrap my head around some of the implications of relativity. Hopefully somebody can help enlighten me with a specific example I am wondering about:
We have 2 objects, A and B, that are ...
- 113
0
votes
1
answer
345
views
Another question about Four-velocity derivation
Consider,again (Question about derivation of four-velocity vector) the following:
For a massive particle with position $x^{\mu}(t) = (x^{0},x^{1},x^{2},x^{3}) \equiv (x^{0},\vec{x})$ we define the ...
- 3,085
1
vote
2
answers
237
views
Naive question about the need to construct the 4-velocity
Special relativity was not born as a 4-covariant theory. Instead, Einstein derivated the kinematical quantities without spacetime,therefore without 4-vectors.
Consider then the following:
First ...
- 3,085
2
votes
2
answers
517
views
Applying Lorentz Transformation
Lorentz Velocity Transformation:
$$v_x = \frac{v_x' + u}{1+\frac{uv_x'}{c^2}}\tag1$$
$$v_x' = \frac{v_x - u}{1-\frac{uv_x}{c^2}}\tag2$$
The speed of spaceship and scoutship are given relative to ...
1
vote
5
answers
577
views
What is so special about the factor $\sqrt{1-{v^2/c^2}}$ in special relativity?
I am studying a book about relativistic equations and special relativity, and I keep seeing $\sqrt{1-{v^2/c^2}}$ everywhere. It is not, as with most of the concepts in special relativity, simply a ...
- 39
1
vote
3
answers
212
views
Relativity and time
Einstein's relativity states that times goes slowly in a moving clock.That means if my friend moves at a speed of $v$ his time will go slowly. But I am also moving at a speed of $-v$ relative to him. ...
- 1,400
-2
votes
1
answer
109
views
What do things move relative to?
When someone says that a spacecraft in otherwise empty space is traveling at a constant velocity of 10 km/h (for the sake of convenience) then what is the reference point for which this measurement ...
- 147
2
votes
1
answer
212
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 ...
- 275