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.
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Lorentz Invariance of kinetic terms for Weyl Spinors
Just to preface things, this exact question has been asked before here, but I don't feel like the answer really clarifies things for me.
The core issue is that we want to construct a 4-vector that we ...
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On the assumption of the nucleus having only kinetic energy in the mass gap demonstration
I have an issue in a step of the demonstration of the mass gap in the nucleus:
Suppose we have a collection of nucleons, particles that made the nucleus. If the nucleus is moving with some momentum $...
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Does proper time have two different values or meanings?
I'm trying to intuitively understand proper time which is defined as the time that is always measured in a moving observer’s or particle's rest frame and is given by the equation
$\Delta\tau = \sqrt{1 ...
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Time and measurement relation to displacement
Is there any other way to measure time without using any type of periodic motion. I think it's a no.
A clock is essentially a periodic motion in which we measure some type of periodic displacement. I ...
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Connection between kinetic and gravitational time dilation [duplicate]
I am learning about relativity and am interested in time dilation. I now exactly understand where the formula of kinetic time dilation comes from and wondered about gravitational time dilation. I have ...
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Finding the Lorentz Velocity for Relativistic Electrodynamics
I'm trying to understand something from my Special Relativity notes.
Assume here that $\vec{E}$ and $\vec{B}$ are perpendicular and $|\vec{E}|>|\vec{B}|$.
Show that there is a frame $\bar{\Sigma}$ ...
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Are there non-smooth metrics for spacetime?
I found this statement in a discussion about the application of local Lorentz symmetry in spacetime metrics:
Lorentz invariance holds locally in GR, but you're right that it no longer applies ...
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Can FTL be done in a way that it dosen't break causality? [closed]
So I was wondering if we could travel faster than the speed of light without creating time paradoxes?could we achieve FTL in a certain way that it dosen't break causality?or does FTL always break ...
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Does Relativity Theory Allow Cyclic Time Travel? [closed]
In the H.G. Wells novel "The Time Machine" and original 1960 movie we saw that the protagonist traveled from his present time to the future and back again to the present just within a few ...
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Tensionless string in Nambu-Goto action
I am studying string theory from the book "String theory and M-theory", written by Becker, Becker and Schwartz. My question is:
We are taught that one of the advantages of introducing a ...
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Proper acceleration along perpendicular directions
Let's take an object (all times mentioned in this problem are proper times). There is a constant proper acceleration
"$a$" on this object in the x-direction for time $t, 0\leq t \leq \tau$. ...
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Can you translate between Newtonian physics and special relativity physics? [closed]
I am asking for clarification on a question on a test I had recently on special relativity. The question was:
"An astronaut is travelling at a velocity of 0.866c. This gives a Lorentz factor of 2....
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Is the law of the lever equation the same in classical physics as in relativity ? Why?
In classical mechanics the balancing lever equation (law of the lever) is
$$M_1 a = M_2 b$$
Where $M_1$ is the mass at a distance $a$ from the fulcrum and $M_2$ is the mass at a distance $b$ from the ...
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In this time dilation explanation, shouldn't gravity and mass affect the example?
recently i've started "exploring" general relativity, and found this example explaining time dilation caused by velocity:
The example was taken from https://en.wikipedia.org/wiki/...
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Relativistic equation for the Doppler effect
From Robert Resnick's "Introduction to Special Relativity", the frequencies in two different inertial frames as shown below,
are related by
$$f = f'\frac{1+\beta \cos\theta'}{\sqrt{1-\beta^...
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Relativistic image doubling effect and quantum foam possible correlation? [closed]
I came across these two interesting articles about the Relativistic Image Doubling RID effect or else called Relativistic Image Pair Creation and was wondering if this phenomenon could be correlated ...
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Special Relativity and Hypersurface of Simultaneity?
In Special Relativity when I move backwards and forwards my hypersurface of simultaneity moves too.
Does time really oscillate backwards and forwards as I move around? Or is it just the application of ...
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A question on negative time and Minkowski Space
Can someone please explain why a point originating inside the cone can never be the cause of an event outside the cone? Is there a real life example of this? The only thing I can think of is from a ...
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Falling/accelerating close to the speed of light
In classical physics velocity and acceleration follow: $v = at$, so an object falling at a constant $10 m/s^2$ for 50 seconds would wind up having a velocity of $500 m/s$.
However, according to this ...
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Weinberg's definition of a single particle state of momentun $p$ $\Phi_{p,\sigma}$ using a standard momentum $k$ in his QFT book
In Weinburg's qft book (chapter 2.5), he uses a standard momentum $k$ and a lorentz transformation L to represent the momentum $p$ of a particle:
\begin{equation}p^{\mu}=L^{\mu }_{\nu}(p)k^{\nu} ...
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Einstein's remark on the invariant nature of mass
Since mass is a Lorentz invariant, it can never change to preserve the vectorial nature of the four-momentum and the other four vectors. Thus the idea that mass changes as speed increases is highly ...
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Does special relativity hold for rotating reference frames? [duplicate]
Could I, for example, create a ‘special-relativity refrigerator’: I place a fresh apple in a centrifuge, spin it up such that the tangential speed of the apple is 0.99c, then enjoy a fresh apple at my ...
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Local curvature in spacetime and spacetime symmetries?
Correct me if I'm wrong, but as far as I understand fundamental symmetries like the Lorentz invariance and the general covariance principle do not hold globally in a curved spacetime. But because it ...
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Why do wires attract when they carry current in the same direction (in relativistic sense)?
I have seen the veritasium video on this subject (https://www.youtube.com/watch?v=1TKSfAkWWN0), but I have this question which am unable to find the answer for.
I have 2 wires carrying same current in ...
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Max value of I in a circuit
I am a EE student.I have been taught Ohm's law which says $I = \frac{V}{R}$.In the limit of$R \rightarrow 0,I \rightarrow \infty$.But I have also taken the course "Electromagnetism II" where ...
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What is $\gamma\lambda_0$ as given in the chapter Relativistic Electrodynamics of Griffiths
According to Griffiths (Chapter: Electrodynamics and Relativity, Section: Relativistic Electrodynamics)-
We have a string with positive line charge $\lambda$. And on the same string a negative line ...
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Can a Foldy–Wouthuysen transformation of Dirac equation in an EM field highlight Thomas interaction?
Based on a previous question Is the Thomas precession a correction to a Lorentz transformation or an interaction? , Thomas precession can be seen as an additional weakly relativistic interaction to ...
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The Relation Between Maxwell's Equations and the Equations of Gravitoelectromagnetism
Under certain conditions, it is possible to approximate the effects of the theory of relativity through equations very similar to those of Maxwell, but for gravity. In these equations, our "...
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Electron affinity from first principles
How accurately has the electron affinity of Hydrogen been simulated (compared to its measured value of 0.754195 eV)?
It seems like this could be a good check on whether two electrons have any ability ...
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Measuring one way speed of light using CMB dipole and quantum entanglement ;) [duplicate]
Edit: before saying this is similar to other questions please at least explain why using quantum entanglement to synchronize clocks has no benefit over the classical way of doing it. I linked an ...
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What is meant by quantum realm and how can we differentiate it from reality? [closed]
The quantum realm is a microscopic world and I have to know its properties. Is our physics applied in that world? Does time could be relative or could it be unpredictable? where does this quantum ...
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Is the Thomas precession a correction to a Lorentz transformation or an interaction?
In the heuristic derivations I have seen for the fine structure of hydrogen includes three terms spin-orbit coupling, Darwin term and corrections to the kinetic energy. For the spin-orbit coupling the ...
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Non-relativistic limit of relativistic energy [closed]
I was reading a book and came across a formula which gives relativistic kinetic energy of a moving body with velocity $v=ßc$, where $c$ is speed of light. The formula is shown in image (equation ...
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Why can't we slap a proton for instead of using particle accelerators?
Very stupid question, but since the mass of a hand is very large compared to a proton, one should be able using a solid slap to accelerate a proton to ultra-relativistic speeds. If I consider a ...
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Comparison of lengths perpendicular to the relative motion
From Resnick's Introduction to Special Relativity:
Imagine two inertial frames in relative motion along a common x-x' axis. In each frame, a stick extends up from the origin along the vertical (y and ...
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Is a blinking pole moving through a barn at relativistic speeds striped?
I am working on a hypothetical to better demonstrate length contraction and I want to verify that the hypothetical is correct.
Let's start with the classic pole-through-the-barn scenario. We have a ...
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About Lorentz transformations
Is this definition of Lorentz transformations correct?
Consider 3+1 dimensional space-time manifold $M$. Let $v,u$ are two vectors of the vector bundle and $g$ be a metric on $M$.
Now we can define ...
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What do you get when you Wick rotate classical electrodynamics?
Say you have some arbitrary distribution of 4-current density and Faraday tensor in Minkowski space, which satisfies Maxwell's equations and the Lorentz force law. Has it ever been found worthwhile ...
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Is the interference pattern of an entangled particle affected by the measurement of it's pair far enough away to take into account special relativity?
I've been considering a theoretical setup for a quantum experiment where 2 particles are prepared with entangled spin. They are then moved far away from one another where particle B is next to Bob who ...
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How does the charge conjugated lepton doublet Lorentz transform?
According to Schwartz, left- and right-handed Weyl spinors transform, infinitesimally, like
$$
\delta\psi_R = \frac{1}{2}(i\theta^j\sigma_j + \beta^j\sigma_j)\psi_R, \quad
\delta\psi_L = \frac{1}{2}(i\...
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What is the covariant version of the dipole moment?
Magnetic dipoles in a rest frame behave as a mixture of dielectric dipoles and magnetic dipoles in another moving frame. However this is sometimes controversial due to Mansuripur's paradox (see ...
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What's the difference between Lorentz transformation properties of Hermitian and Dirac adjoint lepton doublets?
If the lepton doublet transforms like a left-handed Weyl spinor under Lorentz transformations,
$$
L \longrightarrow exp\left[\frac{1}{2}(i\theta_j\sigma^j - \beta_j\sigma^j)\right]L = \Lambda_{sL}L,
$$...
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Dimension of a vector space of all tensors of rank $(k,l)$ in 4D
Dual vector space is the set of all linear functionals defined on a given vector space. The vector space and dual vector space is isomorphic and hence have the same dimension. A rank $(k,l)$ tensor is ...
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Time dilation and contradiction
Suppose we have a reference $R$ and a reference $R'$ with velocity $v \ne 0$ respect to $R$ then we know that:
$$\Delta t = \gamma \Delta t'$$
but respect to $R'$ the reference $R$ has also velocity $...
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Original Einstein papers on theory of relativity
I am looking for definitive way to get einstein original paper on theory of relativity which is both papers of special relativity and general relativity. I am software engineer with graduation in ...
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Relation between Lorentz transformations in QFT and GR [duplicate]
I often have difficulty expressing certain doubts because I am not (not even my self, yes) fully aware of what's going on that bothers me, so forgive me if the question isn't the clearest.
I noticed ...
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What is the velocity in the Lorentz equation relative to when considering a vacuum?
The Lorentz Equation
$\mathbf{F}=q(\mathbf{E}+\mathbf{v} \times \mathbf{B})$
involves a velocity vector $\mathbf{v}$. What is this velocity relative to? Based on e.g. this resource, it seems that when ...
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Gravity vs. EM: action at a distance
Countless texts point to Newton's theory $\nabla^2\phi = 4\pi G\rho$, and remark that the problem here is that a distribution of mass determines the potential instantaneously everywhere, which is ...
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Does Special Relativity apply to waves or particles?
I know that Special Relativity is a classical theory, so perhaps it applies to light waves, but I'm not too sure. The question I want to ask is, does Special Relativity set a bound on particle ...
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Time dilation calcs don't match values cited in recent media
Been reading a lot lately about how space agencies are talking about setting up timekeeping on the Moon and sync that with Earth's system. Nearly every article I read cites: time on the Moon runs ...
