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

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special relativity from minkowsky space-time [closed]

is there any use for learning special relativity from einstein's postulates once you understand the minkowskian structure of space-time . why isn't it straight away taught using minkowski geometry
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Tensors in special relativity [duplicate]

I'm trying to understand tensors, but I've come across the following question: Let $T^{\mu\nu}$ by a $(2,0)$ tensor. Give the definitions of $T_\mu^{\,\nu}$, $T_{\mu\nu}$, and ...
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Black holes and Time Dilation at the horizon

What is the difference between proper time and the observer time? Whilst thinking about Black holes, when we see the Schwarzschild metric $$c^2\tau ^2 = \left ( 1 - \frac{r_{s}}{r} \right )c^2t^2 - ...
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What is imaginary time? [duplicate]

I am not professional physicist; but I am curious about Stephen Hawking's "imaginary time". It would be better to elaborate exactly what it is. I am not confused because of the word "imaginary" but I ...
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Lorentz transformations, why $t$ and not $t'$?

In the derivation of the Lorentz tranformation you get the fromuls: $$x=k(x'-ut')$$ $$x'=k(x+ut)$$ where $k$ is a constant that is yet to be determied ($k= \frac{1}{\sqrt{1-\frac{u^2}{c^2}}}$) ...
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Moving towards a clock at .866C [duplicate]

If you set up a clock that sends out a light pulse every second, and move towards it at a speed of .866c, will the clock appear to run faster?
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How can time dilation be symmetrical? [duplicate]

I recently posted a version of the twin paradox with a twist but here I'd like to propose a new thought experiment all together. Take two clocks, A & B, and place A 1 AU away from B. Once the ...
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Twin Paradox Without Acceleration

So I've been doing a lot of reading about the twin paradox and have encountered several different explanations that strive to resolve it. First off let me start by saying general relativity is not an ...
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Is space-time a Kantian concept - just a concept of the working mind? [closed]

Is space time a Kantian concept – that is, just a concept of the mind at work? That is that there is no ‘out there’ – it’s in the ‘mind’? Relativity might work but it certainly requires a stretch of ...
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Arguments for finite speed of physical processes

When beginning a study of the special theory of relativity, one discovers that the theory of special relativity has as an axiom that the laws of physics are invariant with respect to transformations ...
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Conservation of 4-momentum in special relativity

I understand that the inner product of two 4-vectors is conserved under the Lorentz transformations, so that the absolute value of the four momentum is the same in any reference frame. This is what I ...
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188 views

Is time subjective?

In Minkowski spacetime time is subjective [or more precisely: time is different for every particle/ reference frame]. It is the coordinate time of an observer whose reference frame travels up the ...
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what if the time is zero in one reference frame

Consider measuring the length of an object in another frame of reference. Of course this should happen at the same instance in the frame of reference the measurement takes place in. but using Lorentz ...
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A question on an exercise from Gravitation by Misner, Thorne and Wheeler

My question is on problem 4.1 of Gravitation. In a generic case of electric field and magnetic field(i.e not $E=0$ or $B=0$ or $E$ and $B$ perpendicular), define the direction $\hat{n}$ unit vector , ...
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2answers
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Energy definition in special relativity

I'm going through the early homework assignments for my special relativity course and I've got myself a little confused about energy. I've got a basic understanding of what the 4-momentum is, having ...
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Existence and uniqueness of solutions to $\nabla^a T_{ab}$ in general (or special) relativity

The equation in the title of this question can be a relativistic analogue of the Navier-Stokes equation (in the sense that, in the low-velocity limit, it reduces to Euler's equation when $T_{ab}$ is ...
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179 views

Relationship between the continuity equation and the wave equation

What exactly is the relationship between the continuity equation and the wave equation? Suppose $J^\mu$ is a contravariant vector that satisfies the continuity equation $\partial_\mu J^\mu=0$. Let ...
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2answers
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Equilibrium: Inertia & Applied Force

Thank you for taking the time to read this. I am lay and will understand if the question is closed. My understanding is that in a vacuum, a constant force of $n$ applied to an object of mass $m$, ...
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4answers
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Time dilation derivation of special relativity

In almost all of the derivations using the postulates of special relativity (SR), we use experiments involving light signals. For example, we make a clock using a light signal or measure lengths using ...
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Is proper time an intrinsic value of Minkowski space?

What is proper time? Is it a part of Minkowski space (that is a mere spacetime interval)? Or is it an intrinsic characteristic of massive particles (a sort of "aging")? Example: In the following ...
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Application of special relativity on sound waves

What is the difference between an electromagnetic wave and other waves that amounts to the EM wave following the Special Relativity. I have been reading about the Special Relativity for some time, and ...
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1answer
52 views

Deriving Lorentz transformation - Serway

in Serway, the derivation of Lorentz transformation started from these two equations $$x′=\gamma(x−ut),$$ $$x=\gamma(x′+ut′).$$ The book derived the first equation and then deduced the second. Is ...
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1answer
87 views

How can Lorentz contraction be “directly” measured?

If one is watching a relativistic object of e.g. spherical shape, which emits enough light to be detectable, it will, despite being Lorentz contracted, appear of its natural shape, although rotated. ...
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Explain polarization in RF in which the conductor is stationary

Consider a metal rod parallel to $x$-axis moving with velocity $\vec v =(0,v,0)$ perpendicular to magnetic field $\vec B=(0,0,B)$. Lorentz force will give rise to the electric field $\vec E = - ...
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Driving car with (almost) the speed of the light and switch the headlights on [duplicate]

I'm curious what will happen if we 'drive' a car with (almost) the speed of light, and all of sudden we switch the car headlights on? Will the car headlights ray have double speed (speed of ...
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2answers
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“Vectors” (i.e. 1-tensors) their definition and motivation for relativity

I'm reading Einstein Gravity in a Nutshell (by Zee) and here he defines a vector as an object which is invariant under coordinate representation; concretely, if in one coordinate representation, $V$, ...
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51 views

How much time passed for the passenger traveling with at speed-of-light spaceship? [duplicate]

Let's suppose we have a spaceship with the exact speed of light. If a traveller takes this spaceship to go to proxima centauri (approximately 4 years light away from Earth) and come back, we (as ...
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Is it ok to have two events $A$ and $B$ so that for one person $A$ occurs before $B$ but for another $B$ preceds $A$

Imagine two laser beams A and B are released at the same moment to bounce between two mirrors, A was moving and B was at rest, doing the calculations I found that for a person at rest B would reach ...
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One question about derivation of Maxwell equations

I saw the following way of derivation of Maxwell equations: author starts from Lorentz transformations for the 3-vector of force, then he applies them for the Coulomb law, after that gets the Lorentz ...
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what about doing the laser beam in a moving reference frame but with a ball

I realize the situation where a laser beam moves vertically in a moving vehicle but what if the laser beam was a normal ball If we do the same steps of the proof considering that the velocity of the ...
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2answers
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Is it possible to derive Lorentz transformation equation without Einstein's postulates?

overview Einstein's proof for the Lorentz transformation is given here: from $O$'s view point, $x^2+y^2+z^2 = (ct)^2$. form $O'$'s view point, $x'^2+y'^2+z'^2 = (ct')^2$. We find that Einstein ...
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Relativity and the Higgs field

We know very well that as the velocity of an object increases, its relativistic mass also increases because of an increase in its energy which is directly equivalent to mass. We also know that the ...
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Dragon Ball Z: Hyperbolic Time Chamber *(also increased gravity training) [closed]

Firstly, I am sorry if this seems like a joke. It is not. I have always loved the Dragon Ball series, so this question has been on my mind for a while. Can ...
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Why does the light intensity increase as I approach a distance light source?

Analogy: assume that I have constant rain fall and I have a water bucket to collect this rain. If I am rest relative to the earth, I will catch a certain amount of rain. However, if I now move towards ...
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Energy carried by photon not conserved?

In an imaginary frame of reference traveling with a photon, the length of the path traveled is 0. If the length of the path is 0, isn't it similar to say that the photon is either at the source or at ...
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1answer
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What invariant counting process derives the Minkowski metric?

Starting with Euclidean space, suppose I make a number of copies of a coordinate system all coincident at the origin, together with copies of a standard unit length. For any space interval common to ...
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Understanding the “$\pi$” of a rotating disk

Let us say you are in an inertial reference frame with a circular planar disk. If you take your meter measuring rods (or perhaps tape measure) you can find the diameter and circumference of the disk. ...
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Would infinite time elapse relative to an outside observer if an object was completely at rest?

Here's my reasoning... time dilation due to velocity: t'=t√(1-v^2) v expressed as a % of the speed of light. If you are moving through distance at the speed of light, to an observer at rest relative ...
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Lorentz transformation via light clocks in parallel direction

In order to derive the Lorentz transformation one can use the picture of a light clock. A Photons bounces back and forth between two mirrors. This is then observed in two different inertial systems. ...
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Binding energy and invisible mass

The gravitational binding energy of a sphere is: $U=\frac{3GM^2}{5r}$, the mass defect is $\Delta E=\Delta m c^2$. Putting: $M=\frac{4}{3}\rho\pi r^3$, we get: $$U=\frac{16}{15}G\rho^2\pi^2 r^5$$. Now ...
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Why doesn't time change in the non-relativistic limit of Lorentz transformations?

A simple boost in the $x$ direction is given by: $$ \Lambda = \begin{pmatrix} \cosh(\rho) & \sinh(\rho) & 0 & 0 \\ \sinh(\rho) & \cosh(\rho) & 0 & 0 \\ 0 & 0 & 1 & ...
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3answers
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Special relativity and imaginary coefficient of the time coordinate

I read somewhere that part of Minkowski's inspiration for his formulation of Minkowski space was Poincare's observation that time could be understood as a fourth spatial dimension with an imaginary ...
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1answer
55 views

Relativity Question Fireworks explosion

A firecracker explodes at the origin of an inertial reference frame. Then, 2.0 microseconds later, a second firecracker explodes 300m away. Astronauts in a passing rocket measure the distance between ...
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Why is the speed of light arbitrarily the limit? [duplicate]

I know Einstein was great and all. Why is it that exactly at the speed of light is where infinite energy is required to accelerate any object with mass? Is it simply because the math of relativity ...
5
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1answer
98 views

NASA Theoretical Faster Than Light Space Travel (IXS-Enterprise)

I was recently reading about NASA Faster than Light proposed spaceship, it supposedly will bend spacetime behind the spacecraft, so technically instead of bringing the ship to the destination, "it ...
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1answer
63 views

Can you calculate unix timestamps (universal clock) from any planet?

Given the definition of unix timestamp as the number of seconds elapsed since January 1st, 1970 as GMT+0, without leap seconds, is it possible to create a universal clock that will generate the ...
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Is the total cross section a Lorentz Invariant?

In Peskin and Schroeder's book (P&S), on the botton of page 106, the authors say that the total cross section transforms as its only non-invariant factor, namely: $$ {1 \over E_{A} E_{B} |v_A - ...
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1answer
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How to get the accurate relativistic momentum form for photons? [duplicate]

I have studied from Griffiths, the relativistic form of momentum is $$p = \frac{1}{\sqrt{1-\frac{v^2}{c^2}}} m_0v$$ Now when I evaluate the momentum for photon, I just insert $v=c$ and $m_0=0$ and I ...
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A Subtle Connection Between Time Dilation in SR and GR - Why is this so?

I've been reading a book on General Relativity lately (Gravitation and Cosmology, Weinberg), and I was reading about the weak field approximation. It derived the time dilation in a weak gravitational ...
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Why should photons obey the rules of causality?

This may have a quick answer, but it has been on my mind so here it goes: why, if according to special relativity, do photons obey the rules of causality, if they are inherently timeless. According to ...