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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If an event happens 10 light years away and we observe it here, did it actually happen 10 years ago?

I'm sorry if this question has been answered a squillion times, I need someone with smarts to explain it to me. If an event happens 10 light years away, and we observe it here, did it actually happen ...
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1answer
164 views

Could time be changing without us knowing? [closed]

I've been wondering about relativity for a while now. We seem to measure time by using the speed of light. Light can be slowed down or stopped We assume light doesn't change in a vacuum - yet, how ...
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1answer
75 views

Mass is a stuff or not? [closed]

Einstein said, there can be no clear definition can be give for moving body mass – instead of giving its name as “rest mass”, it is better to mention, “momentum and energy”. Matter is a stuff, ...
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0answers
123 views

Charge above a conductor; effects due to Lorentz force law for moving charges

Currently working through a practice preliminary examination problem. I have your standard charge situated a distance d from a infinite conductor(lets say in the $\hat{z}$ direction and neglecting ...
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1answer
160 views

Can relativistic energy transformation be explained by time dilation and E=h f?

Can one explain the relativistic energy transformation formula: $$E = \gamma\ E',$$ where the primed frame has a velocity $v$ relative to the unprimed frame, in terms of relativistic time dilation ...
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0answers
65 views

Where does the transformation of $\gamma$ come from?

I was reading Tipler, and in his book he says that in order to transform energy, we must write gamma in terms of quantities in the non-primed frame. However his derivation makes no sense to me, it's ...
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3answers
137 views

Is it possible to defy time using speed? [closed]

I have always wondered if we were to travel at past the speed of light (even beyond the current capability) would we be able to slow down time around us? I have asked my teacher at school and he has ...
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1answer
351 views

Relativistic corrections to classical physics formulae

How are classical formulas in physics (such as p = mv, or kinetic energy, or maxwell distribution of speeds) treated with the appropriate relativistic correction/modification? Is it done by using the ...
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1answer
153 views

Lorentz Transformation

I have specific questions about Lorentz transformations specifically about length contraction. Why does length contraction only occur in the direction of travel, (not in all directions) when ...
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1answer
160 views

Ultrarelativitistic particle - what kind of a particle is this?

I have heard many times that we can treat a moving particle as a: classical particle non-relativistic relativistic particle ultra-relativistic particle While I know equations for 1, 2, & 3, I ...
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1answer
121 views

The Movement of Light

I've asked several other questions like this, and I know it's a dumb question but I really can't understand. When light is emitted from a moving source, it still moves straight in that source's frame. ...
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3answers
409 views

How can we deduce the relation $m = \frac{m_0}{\sqrt{1-\frac{v^2}{c^2}}}$ between relativistic mass and rest mass in special relativity? [duplicate]

I was watching a video on Youtube which deduce Einstein's relation $E=mc^2$ and the process of deduction used the relation between relativistic mass and rest mass, which is $$m= ...
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1answer
108 views

Can we obtain non-Lorentzian metric from Lorentzian metric, through renormalization methods?

Since low-energy, non-relativistic thermal field theories are defined in Euclidean spacetime, while high-energy relativistic theories are define in Minkowski spacetime, I was wondering if there are ...
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1answer
136 views

Accelerated Light Sources

When someone accelerates towards a light source, how does the light that's radiating off from it look? I suppose in an inertial frame, all the light should be moving off straight from the source, but ...
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1answer
162 views

From the Poincare group to Minkowski space

In special relativity one assume that spacetime can be locally described by 4 coordinates, so it makes sense to model it as a 4-dimensional manifold. I had the impression that it is assumed that ...
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1answer
79 views

What is the term $t$, in the expression $E=t^{0}m^{1}c^{2}$? [closed]

$E=(t)^{0}(m)^{1}(c)^{2}$. Here, $m$ = mass of the body. $c$ = velocity of light. Is $t$ the time?
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1answer
181 views

Describing the path of light from a moving source with waves [closed]

Can anyone explain the path of light to me, using a wave model, that show the angled path in different reference frames?
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2answers
322 views

2 protons collision (both with different kinetic energies) - I don't know what to put in for $p^2c^2$

The problem statement: Two protons with kinetic energies $W_{k1}=4GeV$ and $W_{k2}=2GeV$ colide and form new particles. What is the mass of newly born particles? There are as many as possible ...
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2answers
157 views

Light in Different Reference Frames

I think I'm just confused, but for some reason I thought that light moving straight in one frame would have to move in the same direction in another frame. I know there are photons-but because I have ...
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4answers
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Relativity and Current in Wire

If an observer is stationary relative to a current-carrying wire in which electrons are moving, why does the observer measure the density of moving electrons to be the same as the density of electrons ...
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0answers
344 views

The connection between classical and quantum spins

I have two questions, which are connected with each other. The first question. In a classical relativistic (SRT) case for one particle can be defined (in a reason of "antisymmetric" nature of ...
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1answer
64 views

Measurement of event time by different observers

Follow up question to Doppler redshift in special relativity A source of light pulses moves with speed v directly away from an observer at rest in an inertial frame. How will the time of the emission ...
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1answer
46 views

Are these data enough to solve this simulataneity problem

observers: S and S'. S stands in midway between two events (say, 2 flashes) located 20 metres apart. He sees two flashes occurring simultaneously. S' notes a 20ns difference in them. S' is moving ...
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5answers
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Can one create mass from energy?

Due to $ E =m c^2 $, one can convert mass to energy. A classic example would be matter/anti-matter annihilation to produce energy (photons, etc.). Can one do the reverse? So could one do something to ...
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2answers
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The problem of a relativistic path integral

Many books have described the path integral for non-relativistic quantum. For example, how to get the Schrödinger equation from the path integral. But no one told us the relativistic version. In fact, ...
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1answer
131 views

Can inertial mass affect gravity of the object? [duplicate]

Every time I watch this TV program that discusses about all the facts about the universe , and it came to a point where they said that as an object approaches the speed of light the mass of the object ...
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1answer
238 views

If two observers pass each other in opposite directions at $.5c$ what would effect on each others clocks be?

Assume an alternate universe with same physical laws as here. In this universe nothing exists except 3 observers, each in a transparent box with a clock. Observer A is travelling at .5c. Observer C is ...
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1answer
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Original paper on Lorentz representation theory

Which was the original paper on the representations of the Lorentz group? Is there even one paper on this, or was this knowledge gained iteratively in a series of papers?
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1answer
107 views

Time relative to pressure? [closed]

We all know the effects of speed on time, and we have a formula for that, but I have a hunch, that time also is relative to pressure, and that by increasing the pressure on matter, in fact time will ...
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0answers
355 views

Collision of 2 particles - calculating the mass and a speed after the collision

Lets say we have a particle of mass $m_1$ which has a kinetic energy $W_{k1}$. This particle collides with another same particle. How can i calculate mass $m_2$ and the speed $v_2$ of the particle ...
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1answer
123 views

Are there (or could there be) electrically charged particles that move at the speed $c$? [duplicate]

A photon, a neutrino (if it has zero rest mass) move at $c$ but what about charged particles? If the answer is no, is there a fundamental reason or just because of the radiation it emits?
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0answers
54 views

Manipulating a formula for a relativistic Doppler shift

Lets say we take the standard configuration when $x'y'$ is moving away from system $xy$ (image 1). By knowing that the phase is constant in all frames $\phi=\phi'$ we can derive the Lorenz ...
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1answer
167 views

How can “quantum particles have positive masses, even though the classical waves travel at the speed of light”?

Clay Mathematics Institute writes about the Yang-Mills and mass gap problem on this page http://www.claymath.org/millennium/Yang-Mills_Theory/: The successful use of Yang-Mills theory to describe ...
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1answer
129 views

nuclear physics homework

i have a homework in our nuclear physics class. the question is "An astronaut whose height in the earth is exactly 6ft is lying parallel to the axis of a spacecraft moving at a 0.9C relative to the ...
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3answers
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Homework - length contraction ($\gamma$ and $u$ are unknown)

I am very sorry for posting these problems in this forum, but i don't know where to post otherwise... I have a weird special relativity problem where i get a relative speed $u$ which is larger that ...
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2answers
371 views

Potential energy in Special Relativity

In Special Relativity, the energy of a free particle is $E^2=p^2c^2+m^2c^4$. But what would be the energy when there is potential energy? If it's something like $E=\sqrt{p^2c^2+m^2c^4}+U$, what ...
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2answers
149 views

How much faster would a Clock without gravity run?

Pardon the misleading title. It is to my understanding that moving/heavy clocks run slow. The Earth itself is under gravitational influence from many sources, and is moving. Is there a way to know ...
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2answers
311 views

Lorentz transformations and a time dilation don't return the same result [closed]

Lets deal with a problem like this: Lets say we have a twin A in coordinate system $x'y'$ who does a round trip to a star which is $12$ light years away and he is travelling with a speed ...
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3answers
134 views

Do you age at different rate at different speed?

This is probably answered many times, but my confusion is the following. In special relativity it is said that there is no preferred coordinate system. Does that mean that for the people at rest ...
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2answers
236 views

Time dilation problem ($\gamma$ and $u$ are unknown)

Can anyone tell me how to solve this problem: Alpha Centauri is $4.4$ light years away from Earth. What speed $u$ would a spaceship headed towards Alpha centauri had to have in order to last ...
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0answers
22 views

Does distance really exist at least for observer which moves at the speed of light? [duplicate]

To our time a light year is the distance that light travels in a vacuum but if we consider time of observer which moves at speed of light we found for light time and distance doesn't really exist. ...
0
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1answer
395 views

Explanation of a proper time (an add)

I have read on web that: Proper time $\tau$ is a time interval measured by a clock which at rest relative to the observer. But lets consider this problem: The plane is flying with a speed ...
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2answers
271 views

Effect of space time relativity on the age of the universe?

So we all heard about the twins paradox to explain einstein's time space relativity. Wikipedia Quote :" In physics, the twin paradox is a thought experiment in special relativity involving identical ...
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1answer
158 views

Can we write the electromagnetic potential covariantly in terms of the four-current?

In the Lorenz gauge, we have a beautiful relation between the four-current and the four-potential: $$\Box A^{\alpha} = \mu_0 J^{\alpha}$$ To get $A$ in terms of $J$, however, we have to use a ...
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1answer
573 views

Frame of reference of the photon? [duplicate]

In the frame of photon does time stop in the meaning that past future and present all happen together? If we have something with multiple outcomes which is realized viewed from such frame? Are all ...
3
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1answer
371 views

Commutator of Lorentz boost generators : visual interpretation

I have always struggled to visualize the correctness of the commutation relation for the generators of the boost in the Lorentz group. We have $$[K_i,K_j] = i \epsilon_{ijk} L_k$$ I fail to picture ...
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1answer
517 views

Why is the stress-energy tensor symmetric?

The relativistic stress-energy tensor $T$ is important in both special and general relativity. Why is it symmetric, with $T_{\mu\nu}=T_{\nu\mu}$? As a secondary question, how does this relate to the ...
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1answer
121 views

Anti-symmetric 2 particle wave function

Suppose we want to construct a wave function for 2 free (relativistic) fermions. As we are dealing with fermions the total wave function has to be antisymmetric under interchange of the coordinates, ...
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Wick rotation and special relativity

CMIIW, but as I understand it, Wick rotation replaces the Minkowski basis (t,x,y,z) with the Euclidean basis (it,x,y,z). Suppose that $t_2=t_1 \cosh \beta+x_1 \sinh \beta$ and $x_2=t_1 \sinh \beta+x_1 ...
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2answers
362 views

Orthochronous Lorentz transformations are time-preserving and $SL(2,\mathbb{R})$

Let's consider the psuedosphere/hyperboloid in $\mathbb{R}^{1,2}$ given by $$x^2+y^2-z^2=-R^2.$$ We know that the Lorentz group $$O(1,2)=\{ A \in Mat(3,\mathbb{R}): A^tGA=G \},$$ where ...