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)

6
votes
1answer
61 views

Does the temperature of a body depend on the frame of reference? [duplicate]

Does the temperature of a body depend on the frame of reference?
0
votes
0answers
36 views

Help needed for Simple derivation for duality of matter

A teacher told showed me a way to derive an equation which shows the duality of matter. We know, $E=hc/\lambda$. and $E=mc^2$ So, $hc/\lambda=mc^2$ We get, $p$ ( momentum ) = $h/\lambda$. How ...
0
votes
0answers
39 views

Rotating magnet and magnetic field intensity change?

if magnetic disc is rotating on it's axis super fast and electric field is produced(because of time varying magnetic field),does this means that in the frame of non moving observer magnetic field no ...
4
votes
0answers
36 views

Special Relativity, refractive index and catching up with a wave

Einstein was partially motivated by the following: With Maxwell's equations, a plane wave is a sinusoidal wave that varies in space in time and moving with speed $c$. These variations are linked by ...
1
vote
1answer
40 views

Time variable in Lorentz transformations

When an object goes with a speed near from the light celerity, it inflates in the direction of its speed. The inflation rate is given by Lorentz transformations as follows: $x'= γ(x-vt)$ where $v$ ...
0
votes
0answers
23 views

Special Relativity and its relation to refractive index [duplicate]

As is known, light slows down (compared to vacuum) whenever it enters a medium. Also, Special Relativity effectively puts a limit on the max. speed of any body. So is it possible for a body (in a ...
4
votes
1answer
81 views

Are all diffusion-like processes described as wave-like in relativity-compatible formulations?

Citing from Wikipedia's article on relativistic heat conduction: For most of the last century, it was recognized that Fourier equation (and its more general Fick's law of diffusion) is in ...
5
votes
1answer
82 views

Staggered Indices ($\Lambda^\mu{}_\nu$ vs. $\Lambda_\mu{}^\nu$) on Lorentz Transformations

I have some open-ended questions on the use of staggered indices in writing Lorentz transformations and their inverses and transposes. What are the respective meanings of $\Lambda^\mu{}_\nu$ as ...
0
votes
1answer
59 views

How do electromagnetic waves/light travel at the speed of light?

When something reaches the speed of light, then time is said to stop, or at least is perceived to have stopped. The reason is that at that speed, the object become infinitely heavy and requires ...
0
votes
1answer
45 views

Norm of the momentum 4-vector

The norm of the momentum 4-vector is $\mathbf{P}.\mathbf{P}$ $= (\gamma mc, \gamma mv).(\gamma mc, \gamma mv) = \gamma mc^2 - \gamma mv^2$ But why is $\gamma mc^2 - \gamma mv^2 = mc^2$?
1
vote
0answers
27 views

A point on a disc travelling at the speed of light [duplicate]

This might be a duplicate of this. I had an interesting thought experiment: suppose that you have a disc of a 1 m radius, where a point P2 inside the disc travels at the speed of light. You have a ...
0
votes
0answers
35 views

Rotations acting on quantum states

Suppose I have a free relativistic massive particle described by a state $|p,\sigma\rangle,$, with $p^\mu=(p^0,0,0,p^3)$, so that $P^3|p\rangle=p^3 |p,\sigma\rangle$ and ...
1
vote
4answers
84 views

If photons travel at the speed of light how can they ever be destroyed? [duplicate]

If photons travel at the speed of light than due to relativity they must experience no time frame in which to be destroyed in the first place so they must be immortal which is silly. So, clearly I am ...
5
votes
0answers
68 views

What type of fields are continuous spin representations?

Continuous spin representations (infinite dimensional representations of the Lorentz group) are pretty rarely discussed, and usually not in that much mathematical details. And usually it is done in a ...
2
votes
1answer
35 views

Deriving Fizeau's velocity equation with special relativity

I can't get to the equation Fizeau found experimentally, $u = \frac{c}{\mu} + v(1-\frac{1}{\mu^2})$, Using special relativity. In particular, where does that minus sign come from?! I have done: $$ ...
0
votes
1answer
44 views

special relativity mirror experiment

There's an experiment in special relativity that involves a light source and a mirror, both placed in a moving object. It is used to derive the time dilation equation. I'm having serious doubts about ...
1
vote
2answers
57 views

How can photon have wave properties if they travel at the speed of light? [duplicate]

I am not a physicist so please excuse me if this is a dumb question. As far as I understand Relativity, as observer (in this case a photon) travels at the speed of light, time stops. So how can the ...
-7
votes
1answer
44 views

Can we produce energy from pure substance having considerable mass? [closed]

According to Einstein's formula, $E=mc^2$. Any substance which has mass can be converted into energy or energy is also existing in the form of mass. So I am very much interested to build a machine ...
-6
votes
1answer
86 views

If E= hv then E= mc2 then h=mc2/v! [closed]

E= pc (1) = hv (2), p= mc (3) From (1) and (2): c= hv/p (4) We put (4) in (3): p=hv/p.m => p2=hvm (5) If we use E=hv in (5) we will get: E= p2/m (6) We use (3) in (6) we will get: E= mc2 From ...
1
vote
1answer
82 views

Derivation of Lorentz Transformations

How can I derive the Lorentz transformations? I don't want to use hyperbolic functions and the fact that the light waves travel by forming spherical wavefronts. Is there a way to derive the Lorentz ...
-2
votes
2answers
87 views

How can we know that the speed of light is constant?

Science say that within a constant time frame the light travels a constant distance. But if time is relative how can it be possible to use it as a reference to say that something is constant?
-2
votes
1answer
45 views

Do we have rest mass according to quantum physics? [closed]

I know wave must be in motion and resonant waves are actually in motion. So I don't understand what is a rest mass of a particle. If a particle is just a wave in a particular field, it should be ...
2
votes
1answer
45 views

4-Gradient Lorentz Transformation

I am currently studying the behavior of a scalar field $\phi$ under a Lorentz transformation $\Lambda$. However I am having trouble understanding why the following holds true: ...
0
votes
0answers
7 views

Head-on collision near lightspead [duplicate]

Assume two objects moving near light-speed (for this experiment let's say $0.9c$) towards each other. The speed is measured from an observation platform at the collision point (as I understood ...
0
votes
1answer
43 views

Does momentum scale linearly with time, assuming a constant nonzero net force, even at relativistic speeds?

I would expect it to, since you'd think the loss of velocity due to relativity would be made up for by the gain in relativistic mass. I'd like this to be confirmed, though. and if so, in whose ...
1
vote
1answer
30 views

Differences in notation of momentum 4 vector

I have noticed three ways to write the 4 momentum vectors: $P = (E/c, \vec{p})$ $P = (E, \vec{p})$ $P = (E, c\vec{p})$ I know how to derive equation 1, and as far as I know, one can use the ...
-3
votes
2answers
51 views

Dark Matter vs. Mass from Kinetic Energy

I was thinking about dark matter, and was wondering if the extra mass due to kinetic energy has been taken into account. Here's what I mean: let's talk about any cosmological object that is known to ...
0
votes
1answer
84 views

If photons end up having a tiny mass, say $10^{-54}~\rm kg$, what would be the universal speed of massless particles?

First, I'm no expert so sorry if I get anything confused but I tried to research as much as could before asking this. So while it is pretty much accepted that photons are massless (Despite this ...
5
votes
1answer
131 views

Obtaining the temperature from Bose-Einstein and Fermi-Dirac distribution

Lets say you are given a distribution function $f(p)$ and you want to define a temperature, $T_f$, for this distribution. (I assume $\mu = 0$.) It is then natural to define a temperature the ...
1
vote
1answer
108 views

Parallel axes between inertial frames in Special Relativity

In "CLASSICAL ELECTRODYNAMICS" by J.D.Jackson, 3rd Edition , $\S$ 11.3, the author gives in equation (11.19) a generalization of Lorentz transformation as follows : If the axes in K and K' remain ...
0
votes
1answer
32 views

Is proper time and proper length relative or absolute in relation to two events?

This question concerns with a problem encountered when doing a question on special relativity. A scenario in which the question is based will be described and the problem will be explained. Scenario: ...
2
votes
2answers
222 views

How is 4-current a 4-vector?

I am looking at Jackson sec 11.9, where he states that the $\rho,\bf{J}$ form the 4-current $$J^\alpha=(c\rho,\bf{J})$$ Jackson says this is from the invariant of the 4-divergence $\partial^\alpha ...
0
votes
2answers
116 views

How to interpret Hermann Minkowski's comments on the construction of spacetime

What did Minkowski mean by his statement: "The views of space and time which I wish to lay before you have sprung from the soil of experimental physics, and therein lies their strength. They are ...
0
votes
0answers
26 views

Applications of octonions in special relativity?

According to the Wikipedia article on octonions: Octonions [...] have applications in fields such as string theory, special relativity, and quantum logic. However, I couldn't find any ...
1
vote
0answers
42 views

Fierz identity for chiral fermions [closed]

First of all I define the convention I use. The matrices $\bar{\sigma}^\mu$ I will use are $\{ Id, \sigma^i \}$ where $\sigma^i$ are the Pauli matrices and $Id$ is the 2x2 identity matrix. I will use ...
0
votes
1answer
62 views

Is the time dilation experiment for real?

A popular experiment is described in books on special relativity, that claims that an atomic clock was flown at high speed and later compared with a similar atomic clock on earth, and it was found ...
-1
votes
2answers
87 views

What particles travel near the speed of a photon? [closed]

I know photons travel at the speed of light. How does the size of a particle determine its maximum velocity? Phonons, Preons, Electron ect. Is there a scale in from the smallest particle's maximum ...
1
vote
2answers
91 views

Why does Special Relativity apply to more than just light?

It is my understanding that time dilation is derived from the constancy of the speed of light in vacuum. I would assume this implies that the quirky consequences would therefore apply only to light. ...
0
votes
0answers
20 views

Relativistic Mass and Potential Energy

In the chapter 16–4 of the Feynman Lectures, Feynman employs a thought experiment to explain why "if two particles come together and produce potential or any other form of energy; if the pieces are ...
3
votes
2answers
52 views

Pole and Barn Paradox w/ Spacetime Interval

I'm having trouble with a pole and barn paradox problem. The problem is as follows: A pole vaulter is running with a pole at $ v=\frac{\sqrt3}{2}c $. Her pole has a proper length of $L$. She runs ...
1
vote
0answers
32 views

Colliding beams vs static target

In this problem I need to find the threshold energy of a positron-electron collision that creates a Z boson (the reverse of the following picture; Z mass 92 GeV) in two distinct cases: collision ring ...
7
votes
4answers
2k views

Am I just some energy traveled at light speed? [closed]

I don't understand $E=mc^2$ very well, and here is my question: Does this equation mean masses are just condensed energy? And does this mean that the extra energy an object has when traveling at ...
1
vote
1answer
53 views

Einsteins theory of relativity and formula of kinetic energy [duplicate]

After seeing both Einstein's theory of relativity ($E=mc^2$) and the formula of kinetic energy (K.E=$\frac{mv^2}{2}$), I noticed that that they are mostly the same, with the only difference that ...
2
votes
0answers
40 views

Is the helicity of photon Lorentz invariant? [closed]

If the helicity of a photon is $+1$ in an inertial frame, then is the helicity of this photon $+1$ in another inertial frame? The helicity operator is $$ h=\mathbf{S}\cdot\hat{\mathbf{p}} $$ with $$ ...
1
vote
1answer
75 views

Where is the mistake in the following rationament [duplicate]

Well... kind of hard to translate in English so bare with me :). Let's consider a wheel that spins in the void. Each point of the wheel has the speed $v = ω r$. That means that for any $ω$, there is ...
4
votes
2answers
166 views

Nature of light in Special Relativity

What is the nature of light in the context of Special Relativity? Is it a photon, or an electromagnetic wave, or something else? I have doubts, because a photon seems to me a quantum mechanical ...
0
votes
2answers
66 views

Is time a coordinate or a parameter in Newtonian mechanics?

In classical (Newtonian) mechanics we only ever seem to consider 3-dimensional space, with physical quantities being represented by 3-vectors. My understanding for this is because in classical ...
1
vote
2answers
48 views

Motivation for usage of 4-vectors in special relativity

I understand that if one considers a 4-dimensional space-time from the outset then 4-vectors are the natural quantities to consider (as opposed to 3-vectors as in Newtonian mechanics), since the ...
3
votes
1answer
62 views

Relativistic correction to Hydrogen atom - Perturbation theory

Given the relativistic correction $$ H_1' = - \frac{p^4}{8m^3 c^2} $$ to the Hamiltonian (i.e. a perturbation), what does it mean when $[H_1', \mathbf{L}] = 0$? The book I'm reading says this implies ...
0
votes
0answers
58 views

Galileo's ship experiment with a laser pen instead of a rock

Ship's mast experiment with the boat moving at speed v: If a rock is dropped from the mast, then for an observer inside the boat they will see this: For an observer outside the boat and on the ...