Tagged Questions

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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Dimensional Paradox Demonstrated by Light Moving Between Parallel Mirrors

In a thought experiment, there are two parallel mirrors which are very long which also face each other. One has a hole in it and one flash from a strobe light shines into that hole. One observer in ...
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Restrictions on the form of a function imposed by Lorentz invariance

I need help proving a couple of theorems regarding the most general form of a function with some particular Lorentz-transformation properties. By the way, the question is possibly (though not ...
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Matrices belonging to orthochronous Lorentz group

My Professor says that all members of the orthochronous Lorentz group may be written as $e^\Gamma$, where $$\Gamma^{\mu}_{\nu}=\Lambda^{\mu \rho} \eta_{\rho \nu}$$ Here $\Lambda$ is an antisymmetric ...
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Are Lorentz transformations a fundamental law?

I've seen derivations of Lorentz transformation but are they really derivations or are we just teasing out the formula using some special cases and then assuming it to be valid for all the cases. Is ...
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Relativistic acceleration in sinusoidal electric field

Consider a relativistic charge $q$ moving with an oscillating electric field $E_z$ with phase velocity $v_p=c$ in direction $\hat{z}$ (e.g. radially polarized laser coprogating with electron). What ...
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Hafele Keating in space: twin paradox redux

So Hafele-Keating made sense of the results by taking the center of the Earth as the reference frame. The westward flight "undid" part of the Earth's rotation and those clocks sped up relative to our ...
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What would be seen when a ship is accelerated to relativistic speeds and back down? [duplicate]

Consider this scenario: Two identical space ships, the SS Observer and the SS Accelerator. Each ship is indestructible and contains an indestructible clock. They begin positioned 1 light-day away ...
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Can we accelerate photons to travel at speed of $1.5c$? Or any $xc$ when $x > 1$? [closed]

Can we move photons to travel at speed greater than speed of light in vacuum? If no then why? For example: I want to send some photons at 1.5c. Is that possible? How a photon of light can go from 0 to ...
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$(\frac{1}{2},\frac{1}{2})$ and $(\frac{1}{2},0)\bigoplus (0,\frac{1}{2})$ [duplicate]

I am confused about the notation. What's the differences between $(\frac{1}{2},\frac{1}{2})$ and $(\frac{1}{2},0)\bigoplus (0,\frac{1}{2})$, or maybe $(\frac{1}{2},0)\bigoplus (\frac{1}{2},0)$ ? (...
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Fixed background theories which feature lorentz invariance?

Are there fixed background theories that also display lorentz invariance? Could be with lorentz invariance being true only approximately at some limit... Realized we can still arrive at time-dilation ...
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What would be seen if a firing laser is accelerated to relativistic speeds then back?

Consider this scenario: Two identical space ships, the SS Observer and the SS Accelerator. Each ship is spherical with a band of mirrored material around the outside and contains a green laser. They ...
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Tachyons and Lorentz velocity transformation

In general, is it possible to apply the Lorentz velocity transformation to a tachyon? I have tried to do so but the results seemed very illogical. Here's my attempt: suppose an evil spaceship named ...
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Time Dilation, Relativity Theorie

i have a question on which i've spent a fair amount of time thinking, but couldnt figure it out : We observe (in rest frame) 2 events happens at the same time, one (Event1) happened on Earth and one (...
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is following alternative interpretation of total energy possible? E=m'v^2 instead of E=m'c^2 [closed]

I have read the paper, http://arxiv.org/pdf/physics/0206061.pdf "Fundamental Disagreement of Wave Mechanics with Relativity", some time ago, in which the author claims that there is another way to ...
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How to find the magnitude of electric and magnetic fields in an arbitary inertial frame?

In the context of special relativity, and using proper Lorentz transformations: If the electromagnetic fields have an uniform value [= constant in space and time] in an inertial frame, how will the ...
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Minkowski geometry definition

The general relativity is based on Minkowski geometry definition with its special properties. The general relativity cant be approved wihout Minkowski geometry definition. Why Minkowski geometry is "...
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What will the point of view be when you move faster than light in a medium?

In water the light become slower to the point where electron in water moving faster than light (in the same medium). So in electron frame of reference what will electron's point of view be? From what ...
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Can I prove observed causality like this?

From an older exercise sheet in my relativity class which I completed, but didn't annotate enough to remember it everything was correct: Let $X$ be an inertial observer noticing that a spacetime ...
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Why is the relative speed between two inertial frames the same for observers in each frame?

Consider two frames $S$ and $S'$, moving relative to each other. If I stand still in frame $S$ and watch frame $S'$, I can measure its speed to be $V$. However, why is this speed the same as the ...
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relativistic addition of velocities using tensor notation? [closed]

I know the way of deriving the formula using usual lorentz transformation formulas,,but is there a way out of deriving it using 4-vector notation??please help
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Redirectioning photons through magnetic lenses

What shape magnet/s would I need to create parallel lines from the ends of a rod shaped magnet?or what shape of magnet would create parallel lines? Is this close?
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Question regarding the mass of an alpha particle when travelling at a speed approaching the speed of light [duplicate]

The speed of an Alpha particle is: 10^7 m/s. This is a speed approaching the speed of light. hence, should the (relativitic) mass of the Alpha particle vary?
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It is not actually a twin paradox but I have no idea what to call it. So let's assume that there are two person named Alvin and Jack. Alvin drive a spaceship at the speed of 0.6c where Jack is ...
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Help me understand Pound and Rebka's experiment

I am a second year undergrad physics student and up until now have done some classical mechanics and some electrodynamics. For some reason I have always been really interested in light. A couple of ...
In QFT we work with Lagrangians which contain terms $m$ such that the relativistic relation $E^2 = p^2 + m^2$ is satisfied. By classical analogy $m$ is called the 'mass'. We note that due to the ...
If I have a momenta $p^{\mu}=(E, p_x, p_y, p_z)$ and transform it via lorentz boost in x-direction with velocity v I'll get for the new 0th component $E'=\gamma E + \gamma v p_x$ why is this in the ...