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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1answer
77 views
A clock devoid of motion
My understanding is that every clock mechanism we have depends on motion of something w.r.t the observer. From atomic transitions to clockwork gears. So, does this property/constraint makes every ...
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1answer
201 views
Special relativity paradox and gravitation/acceleration equivalence
One of the features of the black hole complementarity is the following :
According to an external observer, the infinite time dilation at the horizon itself makes it appear as if it takes an ...
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0answers
143 views
Newton Gravitational constant $G$, Plank constant $\hbar$ , Speed of Light $c$ : The Dream Team of moderators?
The 3 great constants of Nature are well known :
The Speed of light $c$ (special relativity)
The Plank constant $\hbar$ (quantum mechanics)
The Newton ...
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2answers
192 views
What are $\partial_t$ and $\partial^\mu$?
I'm reading the Wikipedia page for the Dirac equation:
$\rho=\phi^*\phi\,$
......
$J = -\frac{i\hbar}{2m}(\phi^*\nabla\phi - \phi\nabla\phi^*)$
with the conservation of probability ...
2
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1answer
221 views
Explanation of equation that shows a failed approach to relativize Schrodinger equation
I'm reading the Wikipedia page for the Dirac equation:
$\rho=\phi^*\phi\,$
......
$J = -\frac{i\hbar}{2m}(\phi^*\nabla\phi - \phi\nabla\phi^*)$
with the conservation of probability ...
2
votes
1answer
92 views
Rotating hoop in Relativity
What does a rotating hoop, with each point moving at a velocity close to the speed of light, appear like with respect from a stationary observers perspective. For example how does the shape of the ...
2
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1answer
266 views
Resolution of twin paradox using Lorentz velocity addition
In the following lecture, starting at minute 29:00 and going further, the professor resolves the Twin Paradox using Lorentz velocity addition. I have a question about this:
Isn't the figure given ...
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3answers
254 views
What is the 'quantum-developed' or 'relativistic-developed' equation of the electrostatic force?
Quantum electrodynamics (QED) is the relativistic quantum field theory of electrodynamics that is the first theory where full agreement between quantum mechanics, special relativity and ...
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4answers
181 views
The necessity of the B field
It is fairly easy using basic special relativity to arrive at the conclusion that the magnetic force effect on nearby charges of wires carrying currents on nearby charges is only due to the length ...
3
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1answer
113 views
How length contracted object would look like?
I have multiple subquestions but they are related.
How would an object look like, which is passing by?
How would a star look like we are travelling to near $c$? Would we see a large blue-shifted ...
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2answers
218 views
Is it possible to reduce speed of light? [duplicate]
Possible Duplicate:
What really cause light to appear slower in media?
This came to me as a question from one of my friend while I was convinced that the answer is NO. But I have read in ...
4
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2answers
206 views
Calculating the commutator of Pauli-Lubanski operator and generators of Lorentz group
The Pauli-Lubanski operator is defined as
$${W^\alpha } = \frac{1}{2}{\varepsilon ^{\alpha \beta \mu \nu }}{P_\beta}{M_{\mu \nu }},\qquad ({\varepsilon ^{0123}} = + 1,\;{\varepsilon _{0123}} = - ...
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2answers
306 views
Faster Than Light Communication Using Gravity?
Suppose two parties $A$ and $B$, some distance apart and at rest relative to each other both had control of one massive local object each.
If party $A$ lifted their local object upward relative to ...
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1answer
129 views
An accelerating and shrinking train in special relativity
Suppose when a train is at rest, it has a length of $L$. Let the position of the back of the train at any time be $A$, and let the position of the front of the train at any time be $B$.
Now assume ...
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2answers
63 views
Does the sign of $\Delta x$ matter in this time dilation calculation?
I cannot for the life of me figure out what I am doing wrong with this problem:
If a high speed particle travels a distance of 39 Km with a half life of 1 micro sec, what must its speed be to travel ...
1
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1answer
115 views
Lorentz transformations for sine wave in random direction
Hello i have been struggling to derive Lorentz transformations for a sine wave, which is traveling at random direction. I started by prooving that phase $\phi$ is invariant for relativity and that ...
4
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2answers
470 views
Does special relativity make magnetic fields irrelevant?
I've heard that special relativity makes the concept of magnetic fields irrelevant, replacing them with relativistic effects between charges moving in different velocity frames. Is this true? If so, ...
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3answers
121 views
Length Contraction And Simultaneity
I wanted to derive length contraction from the Lorentz transformation, but I keep getting stuck on problems with simultaneity in my derivation. At some point, I came across Wikipedia's article on ...
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3answers
238 views
Interaction between a Pair of Particles
We consider a particle, A receiving energy from a second one,particle B in a one dimensional collision.
$$E^2=p^2+m_0^2$$
$$EdE=pdp$$
For particle A:
$$E_AdE_A=p_Adp_A{\;\;\;\;\;\;}(1)$$
For ...
4
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1answer
368 views
Deriving the action and the Lagrangian for a free particle in Relativistic mechanics
My question relates to
Landau, Classical Theory of Field, Chapter 2 - Relativistic Mechanics, paragraph 8 - The principle of least action.
As stated there, To determine the action integral for a ...
2
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0answers
43 views
Reaching the speed of light, rockets [duplicate]
Possible Duplicate:
Double light speed
Someting almost faster than light traveling on something else almost faster than light
Well I've been wondering quite a long time about this ...
0
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1answer
176 views
Does the Earth's revolution around the Sun affect radioactive decay?
Premises:
The radioactivity is either hastened or slowed inside a fast moving aircraft.
Speed of fastest aircraft: 3,529.6 km/h.
The earth's revolution is: 107278.87 km/h.
The earth's ...
2
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2answers
107 views
Stroboscope-and-telegraph problem
Narrative:
Consider, in a suitably flat region, two straight lines which don't necessarily intersect. Let vector $\mathbf{x}$ point along one line, and vector $\mathbf{y}$ point along the other. Let ...
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5answers
589 views
Show the Lorentz Transformation Matrices Have an Inverse
Assume the Lorentz transformations obey the relationship:
$g_{uv}\Lambda^u_{p}\Lambda^v_\sigma = g_{p\sigma}$, where $g_{uv}$ is the metric-tensor of special relativity.
Show then that a Lorentz ...
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3answers
199 views
Spooky action appears to contradict Relativity of time order of multiple events
It is well known that in special relativity observers can disagree on the time ordering of two events.
It is also well known that entangled particles exhibit so called spooky action at a distance.
...
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1answer
223 views
Relativistic Doppler effect
If i have 2 coordinate systems (CS) which are travelling one towards another. CS $xy$ with an observer in its origin and CS $x'y'$ with a source in its origin. Correct me if I am wrong, but i think ...
3
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5answers
323 views
Measure absolute speed
Currently I'm 17 years old, going to secondary school. So, my ideas might be totally wrong...
I know that everything is relative. In the example of speed, the earth moves, and the galaxy moves, etc.
...
6
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3answers
239 views
Is the commutation of all possible operators sufficient to identify a spacelike interval?
It has been claimed (e.g. here) and apparently already been established, that the interval $x - y$ being (called) "spacelike" implies that $\bigl[\hat O (x),\, \hat O' (y)\bigr]=0$ for any two (not ...
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1answer
138 views
Space expansion looking like time dilation
Space looks like time depending on the motion of the observer so I was going to ask if space expansion was the same as the unfolding of time, but this was asked on physics.stackexchange before and the ...
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1answer
86 views
Wavefronts and phase velocity faster than $c$
Lets assume we have parallel wavefronts in a glass of water:
and we put an inclined rod on the water surface:
related to a very small inclining, Vy velocity is greater or much greater then Vx ...
4
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4answers
899 views
How to prove that proper orthochronous Lorentz transformations form a group?
Proper orthochronous Loentz transform are Lorentz transforms that satisfy the conditions (sign convention of Minkowskian metric $+---$)
$$\det \Lambda=+1, \qquad \Lambda^0{}_0 \geq +1.$$
How to prove ...
5
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1answer
197 views
Relativistic contraction for a wave packet and uncertainty on momentum
Consider an electron described by a wave packet of extension $\Delta x$ for experimentalist A in the lab. Now assume experimentalist B is flying at a very high speed with regard to A and observes the ...
3
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2answers
192 views
Magnetic paradox in relativity?
Let 2 electrons A and B be moving parallel with constant velocity $c/10$ in (near) vacuum without a strong gravity field (where $c$ is speed-of-light).
A and B create an electromagnetic field that is ...
6
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1answer
194 views
drift velocity of electrons in a superconductor
is there a formula for the effective speed of electron currents inside superconductors?
The formula for normal conductors is:
$$ V = \frac{I}{nAq}$$
I wonder if there are any changes to this ...
3
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3answers
480 views
Maxwell equations invariant under Lorentz transformation but not Galilean transformations
Why Maxwell equations are not invariant under Galilean transformations, but invariant under Lorentz transformations? What is the deep physical meaning behind it?
4
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7answers
410 views
Information relationship to Special Relativity
How do we write mathematically that "information" cannot go faster than light? And along a similar line of thought, how do we relate "information" with special relativity. Lastly, what is the ...
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1answer
348 views
Derivation of the Lorentz transformation
I have been reading Young's book called: University physics with modern physics and on page 1284 author states that we can derive Lorenz time transformation by eliminating two equations for Lorentz ...
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3answers
128 views
Discarded by Relativity
Both the General & Special Relativity discarded Newtonian mechanics of absoluteness. According to Einstein's view, Time, Mass, Length and Space are interdependent. So, Did Relativity discarded ...
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2answers
127 views
When traveling close to the speed of light
I hope this isn't a stupid question for you guys but here we go.
As you travel close to the speed of light, it is to my understanding you gain mass.. does this also apply when the brain sends ...
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2answers
109 views
3 inertial frames compared in STR
Suppose an event is observed in 3 inertial frames K, K' and K''. The coordinates in K are $(x,t)$ in K' are $(x',t')$ in K'' are $(x'',t'')$. The K' and K'' coordinates are then Lorentz-transformed to ...
6
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1answer
256 views
Is there a strong force analog to magnetic fields?
In special relativity, magnetism can be re-interpreted as an aspect of how electric charges interact when viewed from different inertial frames.
Color charge is more complex than electric charge, but ...
4
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1answer
111 views
Causality without light
Related to my prior question: Would a species insensitive to light have developed special relativity?
Imagine a species insensate to light and other em radiation. They are very attuned to sound ...
4
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6answers
243 views
Would it be possible to develop special relativity without knowing about light?
My understanding of special relativity is that it is fundamentally based on the constancy of the speed of electromagnetic radiation - that this speed is a physical law (or derivable from physical laws ...
3
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1answer
546 views
Darwin term and Zitterbewegung
I've noticed that in the discussion of the fine structure of Hydrogen atom standard QM texts claim that the Darwin term, which corrects energy of $\ell=0$ (or $s$-) states only, is related to the ...
4
votes
4answers
720 views
What happens when a photon hits a mirror?
When a photon of light hits a mirror does the exact same photon of light bounce back or is it absorbed then one with the same properties emitted? If the same one is bounced back does it's velocity ...
0
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3answers
149 views
Time slowing down problem
When someone moves, time slows down for him. Let, a man standing still and another moving very very very fast, this happens for an hour (as measured by the standing man). Time has moved slower for the ...
12
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5answers
864 views
Why did Einstein get credit for formulating the theory of special relativity?
See "The Principle of Relativity" here: http://en.wikisource.org/wiki/The_Principles_of_Mathematical_Physics This was written by Poincare in 1904, a year before Einstein published his theory of ...
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0answers
200 views
Could someone transmit a signal with equally-tuned Casimir plates across the quantum field?
It seems, one could exploit the Casimir effect to send messages across arbitrarily-large distances with carefully-tuned Casimir plates.
Obviously, relativity would preclude FTL information transfer, ...
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2answers
373 views
Lorentz Invariance of Maxwell Equations
I am curious to see a simple demonstration of how special relativity leads to Lorentz Invariance of the Maxwell Equations. Differential form will suffice.
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2answers
102 views
Filming light in motion?
Regarding this video http://www.youtube.com/watch?v=Y_9vd4HWlVA, which claims to "film" light in its motion.
Is it not an absolute nonsense?
Even if photons could even be "seen" (meaning, returning ...
