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

learn more… | top users | synonyms (5)

2
votes
3answers
44 views

Twins Paradox - Does ageing depend on motion?

I am trying to understand the Twins Paradox (relativity) and its implications. Can we infer from the Twins Paradox that the ageing process (cell decay or other biological processes) depends on ...
0
votes
2answers
59 views

Why does the Lorentz transformation have to be a linear transformation?

In my textbook, they say the following before do a proof for the Lorentz transformation: We know that the Galilean transformation x' = x - vt is incorrect, but what is the correct ...
0
votes
4answers
87 views

Why is there a universal speed limit?

I am looking for an answer that does not rely on Special or General Relativity -and without recourse to the fact that the speed of light is frame invariant. Is there another way of showing this ...
4
votes
0answers
47 views

The effect of relativistic near misses

Alice and Bob are both floating in free, empty space. Alice does not like Bob very much. Thus one day, believing that there is no such thing as overkill, Alice takes her programmable hyper-energetic ...
12
votes
1answer
1k views

Confusion I have regarding Einstein's 1905 derivation of LT

In his 1905 paper, Einstein derives the Lorentz transformation using the two postulates of SR;constancy of $c$ for all inertial frames and the Invariance of the laws of physics for all inertial ...
2
votes
2answers
61 views

The action of a relativistic point particle, the meaning of its parametrization invariance and possible potential terms

i am currently toying around with the behaviour of a classical relativistic point particle a bit. For a free one we get the action \begin{align} S =\int_\tau - m\sqrt{- \dot X_\mu \dot X^\mu}. ...
3
votes
3answers
88 views

4-vectors in special relativity and spacetime interval

In one of my vector mechanics lectures, the lecturer said the the space time interval was the dot product of the four position vector. But then he proceeded to show it was this: $s^2$ = $\Delta r^2$ - ...
0
votes
1answer
33 views

Does motion with constant proper acceleration, in a flat region, necessarily mean straight hyperbolic motion?

Is motion of a participant with constant proper acceleration, in a flat region, necessarily straight, hyperbolic motion (with respect to members of any inertial system, in that region)? Or is for ...
0
votes
3answers
50 views

Regarding synchronization of clocks in special relativity

I am trying to read of synchronization of two clocks in same inertial frame in special relativity. Suppose we have two synchronized clocks in an inertial frame placed at positions $x_1$ and $x_2$ in ...
0
votes
0answers
56 views

Why is this 4x4 tensor a 16-dimensional representation of SO(3,1)?

In his QFT book "A Modern Introduction to Quantum Field Theory" (http://www.nucleares.unam.mx/~alberto/apuntes/maggiore.pdf, pages 20-21), Michele Maggiore describes the tensor product of the ...
0
votes
1answer
54 views

Best twin paradox trajectory for constant acceleration rocket?

Let's say I have a rocket that can provide constant (proper) acceleration (let's say of 1 gee) for an infinte amount of time. Let's say I want to use this rocket as a means of "suspended animation," ...
2
votes
1answer
44 views

Why is the Mixed Faraday Tensor a matrix in the algebra so(1,3)?

The mixed Faraday tensor $F^\mu{}_\nu$ explicitly in natural units is: ...
1
vote
2answers
66 views

How is Einstein's arbitrary additive constant $C$ constant during the emission of light?

This is a follow up on this question. In his paper under the title:Does the inertia of a body depend upon its energy-content, Einstein considers two inertial frames $(x,y,z)$ and $(\xi,\eta,\zeta)$ ...
1
vote
0answers
38 views

Does space expansion change value when traveling near the speed of light?

To draw an analogy, we receive roughly the same amount of cosmic background radiation from all directions. However if we were to travel near the speed of light relative to the reference frame where ...
1
vote
0answers
30 views

Is potential energy frame dependent in special relativity?

In newtonian mechanics, As far as I'm aware, only kinetic energy is dependent on frames of reference, since kinetic energy is a function of velocity(squared) and velocity is dependent on frames of ...
2
votes
1answer
42 views

tensor products in special realitivity

Use the definition of a tensor as a linear function on vectors and 1-forms. For a one (2,1) tensor T, use a single vector as argument e.g. T(V) which converts it to a (1,1) tensor. However, if you ...
0
votes
1answer
30 views

What is disadvantageous about measuring time events using light signals sent from events?

In his paper: On the electrodynamics of moving bodies, under the section entitled I. KINEMATICAL PART: § 1. Definition of Simultaneity, Einstein discusses time and gives it an operational definition. ...
0
votes
1answer
67 views

Do relativistic electrons have more charge?

Gauss's law tells us that the total electric flux out of a closed surface is equal to the charge enclosed divided by the permittivity. When a charged particle is moving close to the speed of light ...
1
vote
0answers
33 views

Are relativistic spacecraft slowed down by oncoming gamma ray photons?

I recently read that a proton having an energy of ten billion GeV can travel across our galaxy in about 5 minutes from the frame of the proton. From the Earths frame we would see it take roughly ...
2
votes
1answer
31 views

Derivation of relativistic mean free path

I am working through a short derivation found in Abramowicz 1991 regarding the mean free path of a photon. We have a fluid moving in a particular direction with velocity $v$ and in an inertial rest ...
-5
votes
0answers
45 views

understanding twin paradox [closed]

Is it really possible to observe such a phenomena in real life? I am confused. I have studied time dilation in relation to pion decay but am not sure if it will be true for us human being to observe ...
1
vote
2answers
110 views

The Twin Paradox using reference frame following the ship

The Twin Paradox is undoubtedly one of the most discussed things in special relativity and have a tendency to confuse most of us. Classically, it's resolved by either stick to one of the three ...
-4
votes
0answers
32 views

Relativistic velocity in Special Theory of Relativity [closed]

Prove that, 0.5 m*v^2 , where m = M / (1- (v^2 / c^2))^0.5 ["M" is original mass, and "m" is mass with velocity] doesn't equal to the the Kinetic Energy of a particle moving at relativistic velocity. ...
0
votes
1answer
53 views

Time relativity

Lets say that I am on a spaceship moving with the speed of 0,90c and I am looking on my friend who stayed back on earth. My friend is looking on me. From my perspective, my friend is moving 7 times ...
-1
votes
1answer
45 views

Is heavier object falls slower according to special theory of relativity?

I'm newbie in physics, but have some idea want to know whether it is correct! I saw some information about special theorey of relativity. It just like says "when objects go faster it becomes more ...
-2
votes
0answers
64 views

Could gravitational source provide a fixed reference frame for the speed of light measurements?

I have wondered if a gravitational source could provide the fixed reference frame for the measurements of c? There is, at least one, experiment which could prove my hypothesis wrong, I mean an object ...
2
votes
0answers
33 views

Gauge transformation and Special relativity

While explaining gauge theories, a book makes a comment that the U(1) transformation definition, $ U= e^{i q \lambda(x)}$ is analogous to a special relativity transformation in freely falling ...
1
vote
1answer
50 views

How does work function transform in Einstein's special theory of relativity?

A photon with energy greater than the work function hits the metal, and an electron is knocked off. Now, suppose we were in an inertial frame moving with a velocity $v$ with respect to the metal such ...
1
vote
1answer
44 views

Humans on earth seen from traveling space ship

If I would stand on a space ship traveling with a speed of 0,99c I would be moving 7 times slower from Earth's perspective. But if I would look back on Earth I would see everything moving 7 times ...
-1
votes
0answers
32 views

Higgs Boson mathematical elimination process [closed]

I heard that if the Higgs Boson could be mathematically eliminated, it would be easily accelerate the particles up to the speed of light. If so, how can the Higgs Boson be removed out from the ...
0
votes
0answers
17 views

Is there a standard of rest in the universe? [duplicate]

If you measure the cosmic background radiation you will find that in any direction it is roughly the same. However, if you were to travel near the speed of light relative to the Earth in a particular ...
2
votes
2answers
239 views

Why did Compton use X-rays in his experiment?

Why did Compton use X-rays in his famous experiment? Can it be done using other types of electromagnetic waves?
0
votes
2answers
112 views

Why does gravity affect time?

So Special Relativity states that for all non-accelerating objects of matter the laws of physics are the same. I'm confused on why this law of physic applies to objects in acceleration and gravity ...
1
vote
2answers
123 views

Symmetrical twin paradox without changing direction

If I understood well, in the special relativity 1- A stationary observer sees other moving observer's clock works more slowly than the stationary clock. 2- Motion is relative, the moving observer ...
3
votes
2answers
59 views

Shape and even connectedness of accelerating components in SR is frame dependent?

In some inertial frame consider a disk of radius 1 lightyear at rest. Then along the edge of the disk there are some people in spacesuits at rest hovering right above the disk (which has negligible ...
2
votes
5answers
463 views

Euclidean geometry in non-inertial frame

Refer, "The classical theory of Fields" by Landau lifshitz (Chap 3). Consider a disk of radius R, then circumference is $2 \pi R$. Now, make this disk rotate at velocity of the order of c(speed of ...
2
votes
2answers
60 views

Derive the velocity-additon formula from the Lorentz transformation

In a Euclidian world the sum $s$ of two velocities $v$ and $u$ is so such that $s = v + u$. However, in the world of special relativity that's not the case. Instead, the velcity vector sum $s$ is ...
0
votes
2answers
47 views

Help with relativity simultaneity paradox

To begin I will explain briefly a classic thought experiment used to demonstrate simultaneity; There is a 100m long train rushing towards a 100m tunnel at a fraction of the speed of light, from an ...
1
vote
3answers
103 views

Special relativity: and Lorentz transformation [closed]

An astronaut travels in a spaceship from Earth to Mars, which is located $300LS$ (light seconds) from Earth. The spaceship's velocity is $0.4c$. Both Earth and the spaceship have synchronized clocks ...
-1
votes
2answers
107 views

Special relativity paradox [closed]

Let's say a spaceship leaves Earth and is travelling at relativistic speeds. The spaceship's commander observes a supernova that took place somewhere ahead of the spaceship and then sends a signal to ...
0
votes
0answers
12 views

Luminosity and entropy of a relativistic shell

I am looking to understand more about gamma ray bursts. The review I am reading through describes in equations (111), (112) the luminosity of a relativistic plasma shell, in an inertial frame at rest ...
1
vote
3answers
97 views

If there is no definite speed in the universe, only relative speeds, how does energy increase when velocity approaches the speed of light?

Is the concept of energy increasing as it approaches the speed of light based on the fact that this is only true relative to the observer? Lets say, there's a scenario where a person in a rocket ...
0
votes
1answer
66 views

Time dilation and relativity paradox? [duplicate]

I've come across a weird paradox that I can't answer, I will explain it via the following thought experiment: There is a space-train and an observer 1 light year apart with synchronised clocks. The ...
0
votes
2answers
76 views

Transformation of four-velocity in special relativity

I am revising special relativity introducing more matrix form in the equation. Currently I am reading book in which transformation matrix is defined as $${\Lambda= \begin{bmatrix} \gamma & ...
-4
votes
2answers
71 views

Is special relativity true? [closed]

Is the special theory of relativity true? http://www.npr.org/2014/03/20/291408248/einsteins-lost-theory-discovered-and-its-wrong
1
vote
4answers
85 views

How would the twins paradox be affected by wormholes?

The famous twins paradox where one twin travels to a distant star and returns to find an aged brother can be resolved with general relativity pretty easily, but I was wondering about this: If the ...
5
votes
4answers
89 views

Special Relativity - two beams of light in opposite direction

I just want to first say that I'm aware I am asking a question due to my own confusion and ignorance and not because of anything to do with special relativity. I hope that's alright. What I'm ...
2
votes
1answer
36 views

How to calculate spacetime intervals on a spacetime diagram?

In SR, the spacetime interval is given by the metric: $ds^2=-dt^2+dx^2$ (where I set $c=1$). To calculate $ds^2$ of a worldline on a spacetime diagram, I measure $dt$ and $dx$ of the line of ...
2
votes
2answers
147 views

Two sets of coordinates each in frames $O$ and $ O' $ (Lorentz transformation)

Suppose inertia frame $O'$ is moving at velocity $v$ relative to inertia frame $O$. Let the coordinate systems of $O$ be denoted by $(x,y,z)$ and the corresponding one on $O'$ be denoted by ...
4
votes
1answer
92 views

What would happen in this “close to the speed of light” scenario?

Say you had a really long pole made of a super strong material, and at the you turned it through an angle of (for example) 45 degrees. Turning the pole through a small angle at the bottom would ...