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)

-1
votes
1answer
51 views

Space Contraction [duplicate]

Is there any experimental evidence of space contraction which theory of spacial relativity predicts? You should bear in mind that GPS & muon detection beyond the distance permitted by its half ...
1
vote
1answer
305 views

What would happen to electronic circuits when traveling near the speed of light?

Imagine a space ship, loaded with all sorts of computer systems, traveling near the speed of light. Electricity itself is very fast, and can reach speeds close the speed of light. (up to 99% ...
5
votes
0answers
126 views

What is the proper time used in relativistic non-equilibrium statistical physics?

In the literature one often finds covariant relativistic generalizations of classical non equilibrium statistical equations (Boltzmann, Vlasov, Landau, Fokker-Planck, etc...) but I wonder what is the ...
2
votes
2answers
113 views

Does time dilation imply that events do not take place?

I take two mirrors parallel and facing each other. A light pulse is being infinitely reflected between the two mirrors $M_1,M_2$. $E_1,E_2$ are the events when the pulse is reflected by $M_1,M_2$, ...
0
votes
2answers
129 views

Is it OK to see time dilation and (relativistic) mass increase as phenomena that avoid $c$ being reached? And how about length contraction?

I think I have been exposed since years ago to this line of reasoning: if $ v\to c $, then $ \Delta t \to \infty $. As $\displaystyle v=\frac{\Delta s}{\Delta t} $, it's like a natural reaction to ...
7
votes
1answer
2k views

Would travelling at relativistic speeds have any impact on human biology?

If a person was sitting on a craft that has accelerated to near light speed speed from Earth (e.g. 99.999% of light speed) would there be any impact on his or her human biology due to relativistic ...
-1
votes
1answer
56 views

Can we travel faster than the speed of light? [duplicate]

So my question is completely a theoritical question. For example i have a stick made of the strongest material and lightest material and its lenght is as long as the solar system's diameter. The end ...
7
votes
2answers
2k views

Is Einstein's characterization of “time” as “the position of the little hand of my watch” definitive and binding in the RT?

In Einstein's very first publication dealing with the Theory of Relativity, effectively as a preamble to all subsequent thought-experimental considerations and descriptions, Einsteín put the ...
1
vote
2answers
182 views

Trying to understand one of Einstein's thought experiments

I try to understand Einstein's Relativity: The Special and the General Theory, chapter IX., "The Relativity of Simultaneity". Here's an online version: http://www.bartleby.com/173/9.html. ...
0
votes
1answer
44 views

Tachyons and the light barrier

I read somewhere that if something breaks the light barrier, i.e. a tachyon, that it will take infinite energy to make it go slower than the speed of light. So, does that mean that the object will ...
0
votes
0answers
16 views

At the speed of light [duplicate]

Is it possible to accelerate a body to the speed of light?Why is is said that at the speed of light,the mass of a body would be converted to energy?
5
votes
4answers
254 views

Causality principle and Entropy (Second Law)

I was reading about the light cone in relativity and I got to the point where in order to avoid paradoxes one can introduce the causality principle: Causality Principle: For every inertial ...
2
votes
2answers
97 views

To what fraction of the speed-of-light has any multi-atom molecule (or polyatomic ion) been accelerated?

Of course photons go $c$ in a vacuum, and seems there's data on electrons getting to $0.999999999976c$ and protons to $0.99999912c$. For the twins paradox to be plausible, one of the twins must ...
0
votes
0answers
40 views

The Lie algebra of the Lorentz group is $su(2) \oplus su(2)$. Is there a similar relation for the algebra of the Poincare group?

It can be shown easily, by introducing new generators from the usual ones that we can think of the Lie algebra of the Lorentz group as being built up by two copies of the $SU(2)$ Lie algebra: $$ ...
3
votes
2answers
337 views

Why time is considered a dimension?

Why is time considered to be a dimension? And the other 7 (except the 3 dimensions of space, and the dimension of time) dimensions that string theory suggests, why can't they be realized?
-5
votes
2answers
91 views

Is it possible to travel ONLY through Time and not Space? [closed]

The question is as stated above. I although think, the most probable answer is no, but I really want to know the reason to it. If, One can travel through only space by travelling at the speed of ...
0
votes
2answers
149 views

Does the speed of light have a range of speeds due to medium-dependency?

An EM particle-wave propagates in a vacuum at a constant speed $c$, independent of the source/receiver but dependent on most mediums it moves through. Since the vacuum is a medium, and if logically ...
0
votes
1answer
64 views

Indices of a Pauli matrix transformed in the Lorentz representation

When Peskin and Schroeder want to prove a Fierz identity on page 51, they make use of the identity $$(\sigma^{\mu})_{\alpha \beta} (\sigma_{\mu})_{\gamma\delta} = 2 \epsilon_{\alpha \gamma} ...
3
votes
1answer
113 views

Relativistic Kill Vehicle

What would happen if a significantly supra-molecular object (say ranking from grams to low kilotons) would be accelerated to relativistic speeds (>.10 c) such that its worldline would intersect with a ...
1
vote
0answers
35 views

Hydrogen atom Ionization by Magnetic Field [closed]

The source of a magnetic field (it could be a magnetic dipole) is moving at relativistic speed. This magnetic field encounters a hydrogen atom at rest with respect to the source. Will this encounter ...
2
votes
1answer
75 views

Proof that 4-potential exists from Gauss-Faraday field equation

This is a problem concerning covariant formulation of electromagnetism. Given $$\partial_{[\alpha} F_{\beta\gamma]}~=~ 0 $$ how does one prove that $F$ can be obtained from a 4-potential $A$ such ...
2
votes
2answers
162 views

What exactly is meant by saying that two events had been “simultaneous in an inertial frame”?

In order to address my question based on a concrete example setup let the following two separate events be given: participants $A$ and $J$ encountering each other in passing (additional participants ...
2
votes
1answer
53 views

Time changing potential gives rise to “force”?

Imagine a charged particle inside a Faraday cage (i.e. charge on outside, zero electric field inside, but non-zero electric potential on the inside). Suppose the charge distributed on the outside of ...
0
votes
1answer
25 views

Poynting vector from 1st term in Lienard-Wiechert field

I start with 1st (non-radiative) term from Lienard-Wiechert fields: $$ \vec{E} = q (1-v^2) \frac{\vec{R_{t'}} - \vec{v}R_{t'}}{(R_{t'} - \vec{v}\vec{R_{t'}})^3} $$ $$ \vec{H} = - q (1-v^2) ...
0
votes
1answer
46 views

Lorentz invariance vs. covariance

I am a bit confused whether relativistic theory is Lorentz invariant or covariant. And please explain why?
0
votes
1answer
53 views

How length contraction will work in this case?

Observer is in a spaceship XYZ. In front of him a rod AB is travelling at velocity V. Attached to the 2 ends of the rod are light sources(Red and Green) at different heights. Now these 2 sources emit ...
0
votes
1answer
52 views

Relativistic Momentum in One Frame

(I) What is the momentum of a proton traveling at v = 0.75c? This problem requires a simple substitution. Using the equation $\ p_{rel} = m*u * (1/\sqrt(1 - v^2/c^2))$, where $v$ is the speed of a ...
4
votes
2answers
6k views

Calculating threshold energy of particle reactions

{..everything that follows is in the domain of relativistic kinematics..} Say a particle A collides with a particle B at rest and produces particles C and D. What exactly is the definition of ...
-1
votes
1answer
71 views

4-momentum of massless photons

The time component of a particle's 4-momentum is $$ E'=\frac{E-up}{\sqrt{1-u^2/c^2}}\tag{1} $$ Now suppose it is photons that you are observing from a system moving at $u$ on a line towards ...
0
votes
1answer
40 views

What's the phenomenon where it looks like more particles exist at relativistic speeds?

From the perspective of an observer moving close to the speed of light, the surrounding environment has very high energy which leads to pair production. What is the name of this phenomenon? I can't ...
0
votes
1answer
1k 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 ...
4
votes
2answers
253 views

Maxwell's equations invariant under all linear transformations?

Maxwell's equations in tensor notation read: \begin{align} \partial_\mu F^{\mu\nu} &= J^\nu \\ \partial_{[\lambda}F_{\mu\nu]} &= 0 \end{align} Consider doing a general coordinate ...
0
votes
1answer
53 views

Lorentz contraction in continuously accelerating rod

I was having a little thought experiment about Lorentz contraction, and I couldn't really figure out what would actually happen. Note that I'm not looking for a answer 'this effect is barely ...
0
votes
4answers
140 views

What is the proper time interval for simultaneous events?

Let us take a rod of length L and the two ends A and B have two photon guns. A----------------------B Let the end A fire a pulse (event ...
0
votes
0answers
17 views

Is there any evidence for the increase of mass due to time dilation also causing a strengthening in said mass' gravity? [duplicate]

Logically it make sense that gravity would strengthen with an increase of mass but I want to know if there is evidence for this.
0
votes
1answer
61 views

Derivation of four-velocity using proper time?

Let us say we have an accelerating particle. 4-velocity is given by the derivative of 4-position with respect to proper time. Derivations that I have seen say that: $$d\tau=\frac{dt}{\gamma}$$ But why ...
7
votes
3answers
334 views

Recommended books for a “relativity for poets” class?

I teach physics at a community college and have developed a new course titled "Relativity for Poets," which I will be teaching for the first time in spring 2015. As implied by the title, it's a ...
1
vote
0answers
30 views

Electric fields and magnetic fields [closed]

I would love to know if this is roughly correct with regards magnetic fields. I recently heard someone say that there are people still looking for monopoles. I said I don't think that can be true as ...
1
vote
2answers
89 views

In special relativity, is it correct to say the speed of a body B relative to A is the same as measured by every observer?

Here, two objects A and B are moving relative to each other. I use the Einstein velocity addition formula $v = {v_1 + v_2\over 1 + {v_1 v_2\over c^2}}$ to calculate the relative speed between A and ...
0
votes
1answer
52 views

Dimensionless numbers in relativistic theory

Dimensionless numbers allow physicists and engineers to extend the physical modeling landscape by reducing otherwise complex mathematics to a simple proportional relationship. For example by assuming ...
7
votes
6answers
783 views

Is (rest) mass conserved in special relativity?

I don't understand why it is said that the (rest) mass of a system is not conserved in relativity. I mean, the momentum of a system is conserved (i.e.: it remains constant in a frame of reference ...
4
votes
1answer
383 views

Can a relativistic quantum particle be completely confined into a finite hole?

If we write the Klein-Gordon equation in this form \begin{equation*} c^2 \hbar^2 \nabla^2 \Psi = \hbar^2 \ddot{\Psi} + 2i\hbar (U - mc^2) \dot{\Psi} + U (2mc^2 - U) \Psi \end{equation*} we have a ...
1
vote
1answer
23 views

Matrix dimensions in the spacetime interval equation don't seem to agree? (Possible notation misunderstanding)

The spacetime interval in flat space can be expressed as $(\Delta s)^2 = g_{\alpha \beta} \Delta x^\alpha \Delta x^\beta$. I understand covariant, $x_a$, and contravariant, $x^a$, vectors to be row ...
6
votes
4answers
2k views

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 ...
2
votes
0answers
86 views

Proof that spacetime interval is invariant

I'm trying to understand the proof that spacetime interval is invariant under for any two inertial observers. I know it's easy to arrive at the result using Lorentz transformation but I'm trying to ...
0
votes
5answers
198 views

What is the significance of the “squared” in $E =mc^2$? [duplicate]

If $c$ is just an arbitrary constant, why don't we say $E=mc$ and define the value of $c$ to be $\sqrt{299 792 458} \approx 17314$ meters per second? Or, why not use $E=mc^3$?
0
votes
2answers
54 views

A spin on relativity's twin paradox?

What if a twin is in a rocket in a synchronous orbit with the equator of the Earth while the second twin is standing at the equator watching his twin in space. If we use 0.87c for ease of calculation ...
1
vote
0answers
99 views

Relativistic Momentum and Energy - Lorentz Transformations [closed]

The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Lab is colliding fully ionized gold (Au) nuclei accelerated to an energy of 200 GeV per nucleon. Each Au Nucleus contains 197 ...
-1
votes
1answer
129 views

Stone vs. Atomic Bomb

What would do more damage, a B53, a 9 megaton uranium bomb, or a medium sized stone (2 kg) stone throw at 90% the speed of light. One thing that I know that will have to be considered is that fact ...
1
vote
2answers
70 views

Theory of relativity. Relative to what? [duplicate]

If I properly understand relativity, time ticks faster for an object sitting still than for an object passing by. So, in a universe with only two objects which have the same "age", object A is ...