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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Does invariant mass depends of temperature? [duplicate]

From special relativity theorie we know that $E = mc^2$. When a system acquires energy, mass becomes greater. That is clear for kinetic energy, because we have a formula that gives m as a function of ...
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2answers
73 views

Time Dilation diagram on wikipedia

The wikipedia article on Time Dilation (http://en.wikipedia.org/wiki/Time_dilation) has an explanation involving the following two diagrams: I have some problems with these diagrams. In the second ...
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2answers
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3answers
104 views

How time dilation happens by velocity?

i got many explanation and proving that relative velocity causes time dilation. Einstein's moving light experiment proves it. but that is a clock works with light detector. as detecting the light gets ...
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1answer
60 views

Why is there a cap on the speed at which we can attain? [duplicate]

Also, If you are traveling 1 mph under the speed of light on a train and throw a baseball in front of you at 20mph what would a viewer outside the train see?
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2answers
210 views

How does light change directions? [duplicate]

To the best of my knowledge, light will always travel at the speed of light. How then does it get reflected and change directions? Wouldn't it have to decelerate, come to a stop, and then accelerate ...
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0answers
19 views

A few positrons collide with a solid body at rest; what can happen?

Suppose we have a macroscopic solid object. Now we have a beam of Positrons that is injected into this solid Body at vacuum. What can happen? There will take place a pair Annihilation of electrons ...
2
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1answer
67 views

Canonical field momentum in quantum field theory

In the context of the second quantization and the use of fields in the canonical quantization, the canonical momentum of the field is defined as the derivative of the field by the time coordinate. But ...
0
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2answers
56 views

Speed of light and infinite energy [duplicate]

While browsing some physics websites, I saw that to make an object reach the speed of light, it requires infinite energy and talked about its relation with Einstein's famous equation $E=mc²$. However, ...
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0answers
83 views

What is the status of Lorentz Invariance in String Theory ? Is it global or local?

The questions is simple, what is the status of lorentz invariance in string theory ? Is it global or is it only local ? The proof of absence of anomalies assumes lorentz invariance. However, I believe ...
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2answers
66 views

Would this be correct for kinetic energy in special relativity?

In galilean relativity $$p=mv$$ and $$KE=\frac{1}{2}mv^2$$ If I understand it in special relativity the equation for momentum is $$p=\frac{mv}{\sqrt{1-\frac{v^2}{c^2}}}$$ In galilean relativity ...
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1answer
89 views

How do you calculate time dilation when neither frame is inertial?

I'm reading Hartle, Gravity and read bout the Twin Paradox. I understand why there isn't really a contradiction, one frame is inertial, the other isn't. However, I'd like to know how to calculate time ...
3
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1answer
64 views

Is time a vector in Minkowski space? [duplicate]

I am arguing about this topic with my school teacher in so long time, I want to finish this debate. My teacher's opinion is "Yes, Time is vector" because four-vector has $t$ component, and mine is "...
1
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1answer
146 views

What are the expression for Energy and Momentum of tachyons in terms of their 'rest mass'?

We examine the possibility of tachyons under the criteria that they form the energy momentum four vector that transforms according to Lorentz Transformations. Therefore, $E$$'$ $=\displaystyle\frac{...
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0answers
41 views

How does combining special relativity with quantum mechanics produce spin? [duplicate]

I have read and heard that the intrinsic property of spin that elementary particles have comes from combining special relativity with quantum mechanics. How does combining special relativity with ...
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2answers
35 views

time of flight between two scintillators

I found this page on Wikipedia about finding distance between time of flight of two particles passing past two scintillators, https://en.wikipedia.org/wiki/Time_of_flight_detector, but I can't find ...
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0answers
26 views

Time in the early universe [duplicate]

When it is said, for example, that grand unification took place "Between 10−43 second and 10−36 second after the Big Bang", how are these figures of time derived? Moreover, do these figures have any ...
4
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1answer
84 views

Relative velocity of light in a medium

The speed of light in a medium is independent of motion of source relative to medium but it depends on the motion of observer relative to the medium. I don't understand why it is so.
1
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1answer
129 views

Beyond the speed of light [closed]

Suppose that I can walk/run/travel (not sure if this matters) faster than the speed of light. What would I experience? I know speed of light is a constant and cannot be reached. If someone were to ...
3
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3answers
149 views

Is the maximum possible measurable velocity = 2c

What is the maximum velocity that can be measured between two objects? Is 2C the correct answer? Two photons (A & B) are emitted simultaneously from my position; photon A going north and photon ...
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0answers
72 views

Need some help understanding Relativistic Notation

My question originates from what is done in the book on Quantum Field Theory book by Mark Srednicki on page 21 (if anyone has it). So say you have an inertial frame that is represented in the ...
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0answers
62 views

Momentum eigenstate definition in Eq (2.5.5) of Weinberg Vol. 1 clairification

This is question is related to one asked here: Questions concerning some parts of the section on one-particle states in Weinberg's first volume on QFT. In Eq (2.5.5) of Weinberg's "The Quantum ...
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1answer
70 views

If a car is travelling faster than the speed of light, do the headlights still work? [closed]

If a car is travelling faster than the speed of light, do the headlights still work? If you can help because i really need to know i am going on a trip with my car tomorrow!
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1answer
108 views

Time slows down as you approach the speed of light, travelers observe speeds faster than light travel? [closed]

If I was on a spaceship traveling almost at the speed of light, my time would slow down relative to the time for a stationary external observer. My question is, since we measure distances between ...
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3answers
81 views

If light slows down while passing through a material, does it speed back up while in a vacuum?

Light slows down while passing through, say, water. After passing through the water, does the light speed back up to the "speed of light"? If so, how and why?
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4answers
168 views

Does light in vacuum actually travel at the speed of light? [duplicate]

I know my question sounds like a joke (and I suppose on some level it is) but I'm confounded by the following: As the thought experiment goes, if I'm in a spaceship flying rapidly the people on earth ...
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2answers
80 views

Can we look across Time? [closed]

A photon moves across space, but it does not move across time. If we look at a galaxy that is 1 billion light years away, then we see that galaxy as it appeared 1 billion years ago. Now the ...
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0answers
41 views

From which reference frame is the time dilation factor measured?

I do not know much physics so please try to answer as simply as possible. I am probably confused but I recently learned that in Special Relativity (you can tell that I don't know much physics), the ...
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0answers
48 views

Does Gauss flux theorem hold in relativity?

Does the Gauss flux theorem, stated in the classical electrostatics as $\iint{\vec{E}}\cdot{\vec{dS}}=q/\epsilon_0,$ hold in the case of relative motions. For instance if we observe a charged body ...
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0answers
44 views

Electromagnetic tensor in cylindrical coordinates from scratch

I want to calculate the electromagnetic tensor components in cylindrical coordinates. Suppose I did not know that those components are given in Cartesian coordinates by $$(F^{\mu \nu})= \begin{pmatrix}...
2
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1answer
101 views

Clock on constantly accelerating object approaches Gudermannian limit?

If an object is moving away from X with a constant acceleration of a, its velocity at time t (relative to X and accounting for relativity) is given by: $v(t)=\...
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2answers
104 views

Einstein's train-platform thought experiment — what if we're not talking about light

I'm trying to understand the famous train-platform thought experiment ( http://www.bartleby.com/173/9.html ). I understand part of the Theory of Relativity is that the speed of light is the same ...
0
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1answer
93 views

Does light still slow down in the direction of motion?

This is quite a naive question however I hope to learn from this - I had always learnt a light clock in a space ship is placed like so : That said as the light moves the light will seem to slow ...
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1answer
160 views

Time dilation confusion? [duplicate]

If I understand the theory correctly, time dilation causes a moving clock to tick slower than a stationary clock. If clock A is moving relative to clock B, then clock A ticks slower. However, ...
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2answers
182 views

Griffiths' argument that Newton's third law is invalid in special relativity [duplicate]

I believe that Newton's third law is valid in special relativity. But I read an argument in Griffiths' textbook Introduction to Electrodynamics (3rd edition), where he argued on page 517, that Newton'...
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4answers
67 views

Time dilation and Lorentz transformation

I have trouble understanding the Lorentz transformation to proof the dilation of time. If I use: $$dt ^{'} = \frac{dt}{\sqrt{(1-(v^2/c^2))}}$$ Understanding that $S^{'}$ is the moving frame of ...
3
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1answer
85 views

Signal travels with speed greater than light breaks causality

Signal can't travel at speed greater than light speed in vacuum which is a assumption of special relativity. But if a signal travels at speed greater than $c$ then it will violate causality. I tried ...
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0answers
44 views

Measuring distance in a spaceship moving with 0.5c [closed]

If there are a spaceship moving at a speed of 0.5c that sent a photon when an asteroid was exactly $3\times 10^8$ m away, will the distance between the spaceship and the asteroid when the photon hits ...
1
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1answer
33 views

Particle lifetime doesn't depend upon longitudinal momentum

I am writing a report on an analysis of the $B_{s}$ meson from CDF data, and as part of the lifetime analysis, I have noted down that: $$\tau = \frac{l_{xy} m_{B_{s}}}{p_{T}}$$ Where $l_{xy}$ is the ...
43
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3answers
7k views

Can radioactivity be slowed through time dilation?

Can radioactivity be slowed using the effect of time dilation? If you put cesium, tritium or uranium in a cyclotron at relativisitic speeds, do their half lives become longer in our frame? Could ...
2
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1answer
65 views

Gravitational waves induce changes in the $h_{00}$ (time) component of the metric?

I'm rather stumped by a subtle point regarding metric perturbations of GW. I'm well aware the GW are able to produce changes in the flat space metric, They are transverse and have planes of ...
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3answers
96 views

Time in spaceships near the speed of light

I know that the time on a moving object moves slowly compared to a stationery one, but if someone on a spaceship that moves at V=0.5c and a person is driving it. Will he notice that the clock on his ...
4
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0answers
104 views

General Relativity as a Special Relativistic Field Theory

In this question, I want to consider only the classical case. I have seen the statement that general relativity can be considered as a spin-2 field living on a Minkowski background. In that case, you ...
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1answer
48 views

Representing 1+1 Minkowski space as a surface in 3D Euclidean space

In 1+1 Minkowski space the distance between two points is given by$$ (x_1 -x_2)^2 -(t_1 - t_2)^2.$$ This is different from the Euclidean distance. But is it possible to come up with a 2D surface ...
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1answer
54 views

Exercise prob. in Lorentz invariance [closed]

How we do prove that $\langle p\vert q\rangle$ is an invariant by a boost along $z$ axis knowing that: $$\langle p\vert q\rangle=(2\pi)^3\cdot2\cdot E\cdot\delta(p-q)$$ where $\delta(x)$ is the Dirac ...
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0answers
36 views

Relativistic Particles [closed]

The question: An electron is moving at $0.6c$ in the lab frame. For an observer moving at $0.8c$ in the same direction as the electron's motion, what is the electron's kinetic energy (in MeV)? My ...
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2answers
78 views

A definition for relativistic energy without quantum mechanics

What are the minimal postulates to define energy in special relativity? Let us assume that momentum has not been defined yet (it can be defined from the energy in fact). I expect we are looking for ...
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0answers
144 views

Relativistic electrodynamics between two point charges moving in perpendicular directions [closed]

Let there be two point charges, positive or negative, having velocities in directions perpendicular to each other. I need to evaluate the total interactive force on those (Lorentz force). I do it by ...
-1
votes
1answer
58 views

How to use Special Relativity in simple numericals? [closed]

So I was recently thinking about what an electron's velocity would be after it was accelerated through a potential difference of 1 V. Doing simple calculations like just dividing its energy (which ...
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1answer
151 views

Feynman Lectures on Physics, Michelson Morley question about angle of light

My question is similar, if not identical, to this one, but I don't find the answer satisfying, given the context of experiment. First, here is an outline my understanding of the motivation behind the ...