Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [special-relativity]

The special theory of relativity describes the motion and dynamics of objects moving at significant fractions of the speed of light.

0
votes
0answers
27 views

Constant acceleration space travel: velocity relative to the Earth? [duplicate]

Suppose we are in a spacecraft that is moving away from the Earth along a straight line with a constant acceleration of $1G$, and that this acceleration can be sustained indefinitely. Accelerating at ...
0
votes
0answers
67 views

How can we justify time dilation if we look through an spyglass at Einstein's light clock?

Assume that a space shuttle travels in a circular path having a radius $r_s$ at a tangential speed $v_s$ - a considerable fraction of the speed of light. There is a light clock inside the shuttle ...
15
votes
1answer
257 views

What is the spin-statistics theorem in higher dimensions?

In $d = 3+1$ dimensions, the spin-statistics theorem states that fermionic particles have half-integer spin and bosonic particles have integer spin, in a well-behaved relativistic quantum field theory....
-5
votes
1answer
59 views

When we burn a match stick it did not go at $c$ speed, why?

When we burn a match stick then mass is converting into energy then according to the relativity match stick particles should go at speed of light but it did not happen why
-1
votes
0answers
29 views

why does speed of light have a limit?why cant it go faster? [duplicate]

Do we have any proof that speed of light can't go any faster? what is the reason that light cant go faster?
0
votes
3answers
92 views

Why are Spin 1/2 particles invariant to $4\pi$ rotation loops while Spin 1 particles are invariant to $2\pi$ loops?

Why do Spin 1/2 particles when turning them by 360 deg get a phase factor of -1 and a loop of 720 deg leads to the identity while for spin 1 particles a loop of 360 deg gives already the identity?
0
votes
0answers
22 views

What would happen to a vibrating string moving forward at relativistic speed?

Suppose a physical string set in a frame vibrating with enough frequency and amplitude that the middle point of the string reaches 25% of the speed of light. Now suppose that the entire frame with the ...
0
votes
0answers
40 views

Proving two space-time intervals are equivalent with matrix algebra

η=$ \begin{bmatrix} -1 & 0 & 0 & 0 \\ 0 & 1 & 0 & 0 \\ 0 & 0 & 1 & 0 \\ 0 & 0 & 0 & 1 \end{bmatrix} $ v=$ \begin{bmatrix} ct\\ x\\ y\\ z \end{...
0
votes
2answers
112 views

Rotating Rod in Special Relativity

Statement of the Problem In frame $F'$ with co-ordinates $(t',x',y',z')$, a straight rod rotates in the $x',y'$ plane with angular velocity $\omega ′$ about one of its ends. The fixed end is located ...
0
votes
5answers
102 views

Varying constants in special relativity [closed]

The first thing you learn in special relativity is: All "inertial" frames of reference are equivalent. There is a frame - invariant speed limit, usually called speed of "light." So, geometry is a ...
0
votes
1answer
95 views

Retarded time miscalculation?

I am trying different methods for finding the retarded time in an electromagnetism problem. I'm getting different results, but I'm not sure what I'm doing wrong. Consider a charge at the origin that ...
0
votes
2answers
65 views

Spacelike and timelike intervals confusion

I'm confused about this, specifically the spacetime interval. A timelike interval is one in which 2 events can be related to each other in a given reference frame within its light cone, that is, it ...
0
votes
0answers
70 views

Is there any change in temperature due to special relativity? [duplicate]

Say I am travelling in a spaceship very close to the speed of light. Would there be any change in temperature in the spaceship relative to outside the spaceship? Please explain in detail.
0
votes
1answer
20 views

Mass and energy in special relativity [conservation of energy problem] [closed]

A certain quantity of ice at $0$ celsius melts into water at $0$ celsius and in doing so gains $1.00$ kg of mass. What was its initial mass? Now the problem with my solution is that it of course ...
1
vote
0answers
116 views

What is the Lorentz group composition of two electrons?

We know that the wavefunction of an electron transforms as Dirac spinor $(1/2,0)⊕(0,1/2)$ under the Lorentz group $SO(3,1) \sim SU(2)\times SU(2).$ Which representations can we form with two ...
0
votes
1answer
77 views

Question about special relativity in Carroll lecture note

In the lecture of General relativity by Carroll, page 7 is written that: Notice the distinction between this situation and that in the Newtonian world; here, it is impossible to say (in a ...
2
votes
2answers
81 views

Is there a connection between the energy distribution and time dilation?

Can anyone please help me understand what is descibed bellow? Scenario 1. We have a pair of atomic clocks. Let's call them clock A and clock B. We switch both of them on at the same time. Clock A ...
1
vote
0answers
25 views

conventional matrix notation for distance interval

Why matrix notation for distance interval is represented by this? $$g_{\mu \nu}\Delta X^{\mu}\Delta X^{\nu}=(\Delta X)^Tg (\Delta X)=\Delta X^{\mu}\Delta X^{\nu}g_{\mu \nu}$$ Could you explain ...
1
vote
2answers
90 views

Paradox are all 4D distances zero?

The 4 dimension distance from the origin of a point is $\sqrt{x^2+y^2+z^2-t^2}$. Which means the 4 dimensional distance on the light-cone is zero. Take a point A and a point B in the future at ...
0
votes
1answer
58 views

Dirac matrices in 1+1 dimensions

Given $\gamma^\mu$ in 1+3 dimensions with signature $(+,-,-,-)$, how can I obtain Dirac matrices in 1+1 dimensions expressed in terms of the $\gamma^\mu$?
-6
votes
1answer
39 views

SuperString theory and mass-energy equivalence [closed]

Please ignore the previous question. As I had said that I knew that the energy released in electron-positron mutual annihilation is 511keV in form of gamma rays. Please reply- What is(or whether there ...
2
votes
3answers
69 views

Explanation of Lenz's Law phenomena

If we drop a magnet through a copper pipe (without it touching any of the sides), it would fall slower than it would if there were no pipe. Having the pipe otherwise accelerate the magnet would be in ...
0
votes
0answers
41 views

Retrieving the non-relativistic formulas for electric and magnetic fields from relativistic formulas

I was checking the formulas for the electric and magnetic fields components E and B given in this link from Wikipedia: https://en.wikipedia.org/wiki/Classical_electromagnetism_and_special_relativity#...
1
vote
1answer
54 views

Poincare group and free theories

How exactly is the Poincare group related to the free relativistic theories in quantum field theory? I know Poincare group is the Lorentz group along with translations but don't see any connected why ...
0
votes
0answers
38 views

How to calculate mass from time dilation and radius?

I'm new to this site and I'm been searching the internet all over for this solution. I'm looking for an equation, that if given the time dilation at the surface of an object and its radius, it will ...
2
votes
3answers
84 views

Space (Lorentz-Fitzgerald) contraction

Lorentz transform can be written, according to wikipedia, as: $$ \begin{align} ct' &= \gamma \left( c t - \beta x \right) \\ x' &= \gamma \left( x - \beta ct \right) \\ y' &= y \...
3
votes
5answers
402 views

Could be possible to build a 4-vector in special relativity whose spatial component was the electric field E?

Hi everyone and sorry for my English. I would like to know if I can build a legitimate 4-vector as $E^\alpha=(E^0,\mathbf{E})$. I'd like you to check if my way is correct. 1- We already know that $\...
0
votes
1answer
61 views

Why do two moving inertial frames of reference atribute the same velocity to each other?

In both relativity and Newtonian mechanics, it is a self-evident axiom according to which two inertial observers who move relative to each other measure the same velocity of, say, $v$. I want to know ...
0
votes
0answers
35 views

A Scalar Function Tranformation — Question on Notation in 't Hooft Document

I started reading a document by Gerard 't Hooft which can be found here. Right at the start I am puzzled by a simple expression. It is equation 2.2 showing how a scalar function transforms. I ...
1
vote
1answer
85 views

$\partial^{\nu} \partial_{\nu}$ vs. $\partial_{\nu} \partial^{\nu}$

I was doing a problem regarding field theory. I am given the following lagrangian density: $$\mathcal{L}=\frac{1}{2}\partial_\mu\phi_i\partial^\mu\phi_i-\frac{m^2}{2}\phi_i\phi_i$$ for three scalar ...
1
vote
3answers
104 views

How does relativity affect the view of different observers

I understand how the Lorentz contraction works but was thinking about how that would manifest itself as perspective of a distant object by two different observers. One is traveling at high velocity ...
-1
votes
2answers
87 views

Relativity thought experiment - spaceship travelling at speed of light [closed]

I have basis knowledge in special relativity, but I haven't studied it for too long and I'm stuck in a simple thought experiment. Assume that there is a spaceship departing from the earth at speed of ...
0
votes
1answer
67 views

Gear Theory — Entanglement — Spooky action at a distance explained? [duplicate]

Nothing can travel faster than the speed of light. Not even an electrical signal. Entanglement seems to violate this. But, does it? Imagine 100 gears lined up in sequence all the way across a ...
3
votes
1answer
65 views

Faster than light speed transfer of certain event

I am CS/Math person I am not quite sure what it means in physics information cannot be transferred faster than light (FTL). I tried to understand the proof of no transfer theorem but I lacked the ...
1
vote
2answers
87 views

What is the reasoning behind 1 step in Einstein's derivation of the Lorentz Transformation

In Einstein's book "Relativity" there is a wonderful derivation of the Lorentz transformation, requiring no more than high school algebra (pp. 117 - 121). It is quite clear but I do not understand ...
1
vote
1answer
37 views

About $(0,1/2)$ representations

While studying representations of Lorentz group, we get the generators to be $J_{i}$ - rotations and $K_{i}$ - boosts. We define $N_{i}^+$ and $N_{i}^-$ operators and these operators obey the same ...
1
vote
2answers
53 views

Reflective photon rocket

A space-craft, also of rest-mass $M_0$ and initially at rest, is propelled by reflecting a plane-parallel beam of photons, generated at a rate $αM_0$ from a stationary source mounted on the launch pad,...
1
vote
2answers
217 views

How can the universe be dodecahedron-shaped?

Physicsworld references "Dodecahedral space topology as an explanation for weak wide-angle temperature correlations in the cosmic microwave background" by J.-P. Luminet et al., published in Nature (...
0
votes
1answer
50 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 ...
1
vote
2answers
66 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 ...
-2
votes
1answer
72 views

How can I go and also not go faster than light?

Suppose I am in a spaceship. In this spaceship there is also my friend. So my friend and my relative velocity is zero. So no matter how fast my ship goes my friend's velocity relative to me is zero($0$...
-2
votes
1answer
45 views

The delay of light in the air in the experience of Michelson

An experiment to test the special theory of relativity was carried out in the air. Therefore, the speed of light is equal to the phase velocity of light; it is different from the speed of light in a ...
0
votes
2answers
41 views

Momentum in the rest frame

I am a little confused over the terminology of the rest frame. Say a photon collides with a massive particle then from the rest frame of the massive particle would it be the photon or the particle ...
1
vote
0answers
32 views

Is the speed of light greater if traveling at an initial velocity greater than zero? [duplicate]

I'm reading "a brief history of time" and he states "the speed of light should be the same whatever the speed of the source, and this has been confirmed," (24). Why is it not increased if it has an ...
0
votes
0answers
32 views

Variation of vector field under Lorentz transformation and gauge transformation

In a paper I am reading, it is stated that under a Lorentz transformation, the coordinates transform as $x^{\mu} \to \Lambda^{\mu}_{\nu}x^{\nu}$, and so the change in the (vector) field at the same ...
1
vote
0answers
29 views

Momentum in capacitor field; How can an EM field have zero momentum density but non-zero momentum flux?

Consider the case of a simple, stationary parallel plate capacitor oriented with its plates lying in the x-y plane. The E-field is simply given by: $$\vec{E} = \frac{Q}{\epsilon_0A}\hat{z} $$ with ...
0
votes
2answers
84 views

Clock in a sealed box at half the speed of light. How would it know it is moving?

Consider a clock enclosed in a sealed box here on earth syncronized with my wrist watch. I send the boxed clock around the galaxy a couple of times at half the speed of light (or the full speed of ...
0
votes
0answers
52 views

Everyday magnetism as a consequence of perfect balance of electrical effects

Consider two charges moving in space, both at the same speed and parallel to each other. Because they are moving, they will behave like two currents and will have a magnetic field associated with ...
1
vote
1answer
65 views

Why would it take so great distance for an object to have the acceleration due to gravity?

Let's suppose that in a certain reference frame, a hyperbolic coordinate is used, i.e. $(x,t)=(r\cosh \omega, r \sinh \omega)$. On each hyperbola $r=R$, where $R>0$ is a constant, the proper ...
0
votes
1answer
56 views

Distance contraction in special relativity

Say that a comet explodes over Jupiter. And we were watching this from earth. There should be a time lag in reality as the light takes finite time to reach us. Now if we supposed an inertial frame ...