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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Special Relativity [closed]
Could someone explain to me how special relativity works?
I know there are thousands of sources and databases of knowledge out there, but I find it difficult to understand, even after reading up on ...
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1answer
132 views
Vector transformation in special relativity
Please note that I am very new on this website so have some difficulties in writings as required here but trying really hard to learn quickly. La-Tex is the main problem but please understand me that ...
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2answers
147 views
Special relativity, spacetime, velocity and units
We all know that space and time are the fundamental units, means no mathematical expression can express their relation to other variable fundamentally. But as we know that moving rod has a contracted ...
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1answer
114 views
Time Contraction
This is my first time posting on this site. I am a computer programmer that stumbled across a physics text book and have a question on special relativity. So firstly, I understand that there is no ...
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2answers
155 views
What is the relativistic action of a massive particle?
all Lorentz observers watching a particle move will compute the same value for the quantity
$$ds^2 = -(c \, dt)^2 + dx^2 + dy^2 + dz^2,$$
$$ds^2 = g_{\mu\nu}dx^{\mu}dx^{\nu},$$
and ''ds/c'' is then ...
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1answer
87 views
How does light travel create time travel violating causality?
Saw a question about faster than light travel... I still have the same question though none of the answers offered any resolution for me.
It is so summarily assumed by all physicists and commentaries ...
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1answer
128 views
Could we have assumed the speed of light to be different in different reference frames?
Ptolemy's model of universe assumes that our earth is the static center of universe and everything else move relative to it (ref: The grand design ch:3). This model would give us a consistent picture ...
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2answers
143 views
Is there a “present state” of distant stars if simultaneity is relative?
Special relativity theory says simultaneity is relative, meaning that different observers will not agree on what happened first and what second. Does it then make sense to say that looking at distant ...
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2answers
414 views
Is 2.5x speed of light possible between two objects?
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http://www.hs.fi/ulkomaat/Kaukaisin+havaittu+galaksi+et%C3%A4%C3%A4ntyy+maasta+valoa+nopeammin/a1305618680897
The main excerpt is:
"Distant galaxy moves away from us as ...
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0answers
65 views
Noether's charge due to lorentz transformation [duplicate]
Possible Duplicate:
What conservation law corresponds to Lorentz boosts?
For a relativistic free particle, What is the Noether charge generated due to Lorentz transformations? What is ...
2
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2answers
151 views
Is there any law that prevents an object with mass to become massless?
I got into a discussion with my physics teacher about the speed of light and I asked
What if an object with mass was to lose mass as it gained speed-- would that allow for an object to eventually ...
3
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0answers
78 views
How would an observer perceive movement on a train that's travelling near the speed of light?
Person A is on Earth and a train (or whatever you want to imagine) travels past him at near the speed of light. How would person A perceive movement on the ship? If time is slowed on the ship from the ...
3
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4answers
549 views
Relativistic momentum
I have been trying to derive why relativistic momentum is defined as $p=\gamma mv$.
I set up a collision between 2 same balls ($m_1 = m_2 = m$). Before the collision these two balls travel one ...
3
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2answers
352 views
Lorentz transformations in Dirac equation
Let's denote a spinor $\xi$. If $(\theta ,\phi)$ are the parameters of a rotation and pure Lorentz transformation, then how $\xi$ could be written as
$$\xi ~\rightarrow~ \exp\left(\ i ...
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2answers
168 views
When moving fast Time slows down Vs speeds up
I was watching an old cartoon movie where a scientist makes a gadget, which when bound on the wrist, freezes the movement of the whole world. So, that one may do 100s of things in a single second. ...
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0answers
185 views
Is there an easy derivation of relativistic velocities addition and relativistic doppler shift?
Is there an easy derivation of relativistic velocities addition and relativistic doppler shift?
I'm looking for some easy derivation of the above. Like this ...
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0answers
48 views
How could I get to $E=mc^2$? [duplicate]
Possible Duplicate:
Did Einstein prove $E=mc^2$ correctly?
What was Albert Einstein’s proof for $E=mc^2$?
I wanted to know, How did Einstein come up with $E=mc^2$. I read it´s related to ...
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4answers
217 views
Mass-Energy relation
Einstein mass- energy relation states $E=mc^2$. It means if energy of a paricle increases then mass also increases or vice-versa.
My question is that what is the actual meaning of the statement ...
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4answers
623 views
What was Albert Einstein's proof for $E=mc^2$?
Most people know the famous equation:
$$E=mc^2$$
What were his steps of thinking for this equation that helped us discover so much about our world?
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2answers
197 views
Another faster-than-light question
Imagine we have something very heavy (i.e supermassive black hole) and some object that we can throw with 0.999999 speed of light (i.e proton). We are throwing our particle in the direction of hole. ...
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1answer
607 views
How realistic is the game “A slower speed of light”?
The game "A slower speed of light" from MIT claims to simulate effects of special relativity:
Visual effects of special relativity gradually become apparent to the
player, increasing the ...
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1answer
78 views
What else does the fabric of space-time do?
I know that, the fabric of space is bended so there is a path for another planet to follow to cause gravity I.E. the sun and the earth ( i think)
Is htere any othe rthing's the fabric of space-time ...
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1answer
153 views
Special Relativity & Mirror Reflection
If you move at $5$ $ms^-$$^1$ towards a plane mirror, your reflection moves $10$ $ms^-$$^1$ towards you.
But what happens if you're moving much faster, say $0.8c$?
Would your reflection move at ...
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1answer
324 views
Minkowski diagram, hyperbola and invariant quantity of relativity
I have heard of the invariant quantity $\Delta s$ in relativity for which I have stumbled upon an equation $\Delta s^2 = \Delta x^2 - c \Delta t^2$. This reminds me of hyperbola, which has general ...
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9answers
444 views
How to explain (pedagogically) why there is 4 spacetime dimensions while we see only the 3 spatial dimesions?
I have been asked this question by a student, but I was able and in the same time incapable to give a good answer for this without equations, so do you have ideas how one can explain this in a simple ...
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2answers
174 views
What equations do I use to do basic time dilation problems?
I understand the concepts of relativity, but I don't know where to go to set up equations to do any actual calculations. For example, what equations would I use to find out the following:
A ship ...
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1answer
734 views
Violation of Newton's 3rd law and momentum conservation
Why and when does newtons 3rd law violate in relativistic mechanics? Check this link http://www.animations.physics.unsw.edu.au/jw/Newton.htm.
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1answer
364 views
Airplane example of special relativity
I'm struggling with an introductory example of special relativity. We haven't done the math yet so I would like an explanation based only on the fact that the speed of light is the same in every ...
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1answer
112 views
Time dilation $t'=(1-\frac{v}{c})t$ instead of $t'=\frac{1}{\gamma} t$
Suppose we have a train moving. When the origin of train's frame coincides with the origin of observers frame; the the time is set to zero. At that very instant, a photon is emitted from train towards ...
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1answer
50 views
Testing covariance of an expression?
This is something I've been unsure of for a while but still don't quite get.
How does one tell whether an expression (e.g. the Dirac equation) is covariant or not? I get it for a single tensor, but ...
5
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1answer
120 views
The notion called aether
I am trying to learn relativity theory and going through an introductory text on special relativity. I stumbled on the Michelson-Morley experiment. The book claims (accounts) that the result of this ...
4
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4answers
310 views
Relativistic mass and imaginary mass
The (relativistic) mass of an object measured by an observer in the $xyz$-frame is given by
$$m = \frac{m_{rest}}{\sqrt{1 - \left(\frac{v}{c}\right)^2}}.$$
Mathematically $v$ could be greater than the ...
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2answers
122 views
Speed of Entropy change
If time in systems moving with different speed goes differently, does speed of entropy change differ in these systems?
(is "speed of entropy change" a valid term? can we compare them?)
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1answer
85 views
Faster than light due to reference position [duplicate]
Possible Duplicate:
Travelling faster than the speed of light
Please try to follow and clarify me I've been curious about this for a long time as it seems a bit paradox due to the rule that ...
3
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2answers
223 views
The order of seeing event in different spacetimes
Assume this question:
Three events A, B, C are seen by observer O to occur in the order ABC. Another observer O$^\prime$ sees the events to occur in the order CBA. Is it possible that a third ...
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1answer
221 views
Minkowski diagram and time dilation
After i figured out how to show length contraction in this topic. I tried to use a similar way to show time dilation in Minkowski diagram. Time dilation means that time interval between two events is ...
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3answers
279 views
Minkowski diagram and length contraction
The length contraction means that an object is the longest in the frame in which it is at rest.
Lets assume i have a meter stick with length $\Delta x$ in my rest frame which is $x,ct$ and i want to ...
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4answers
179 views
Find total energy and momentum of an moving electron in a rest frame
I have an electron moving with speed $u'$ in a frame $S'$ moving with speed $v'$ relative to a rest frame $S$.
How do I find the total energy and momentum of the electron in the rest frame $S$?
I ...
4
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1answer
182 views
What do I see if I move quickly past a charge surrounded by iron filings?
This might be a straightforward exercise, in which case I apologize. Suppose I surround a charge by iron filings initially oriented in some fixed direction, and I then move past the charge at an ...
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1answer
57 views
Assuming collision , are there fundamental forces associated with absorbtion?
I just learned that strong and weak nuclear forces relate to decay/emission.
I know absorbtion depends on Energy levels(QM) and heat(thermodynamics , kinetic energy , entropy) and E = gamma mc^2 ( ...
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0answers
18 views
Is there a way to compute or explain if a decay prefers decaying into mainly mass or mainly energy?
Is there a way to compute or explain if a decay prefers decaying into mainly mass or mainly energy ?
I know quarks prefer to decay into the most massfull quarks : ...
15
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3answers
740 views
What is the length of 1 second in meters
If time is treated as a fourth dimension of spacetime, what is relation between length and time units?
Or in other words, how can I convert time units to length units, for instance seconds to meters?
...
2
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1answer
500 views
Lorentz transformation matrix and its meaning in Minkowski diagram
I have sucessfully derived the Lorentz matrix for the boost in $x$ direction and its inverse. So I know how to get these two matrices:
$$
\Lambda =
\begin{bmatrix}
\gamma & 0 & 0 & ...
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2answers
160 views
Does infinite energy imply Infinite mass (and vice versa)?
If some kind of source was able to supply an infinite amount of energy, does that imply that it also must have an infinite mass? Is the contrary also true?
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0answers
122 views
What facts and examples should I use in a debate with a Relativity Denier? [closed]
I have been asked to 'defend Science' at a Creationist event in Minneapolis, MN, and the guy I'll be debating is against 'Einsteinian Relativity', or as he characterizes it, the idea that there is no ...
5
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2answers
285 views
The Lagrangian in Scalar Field Theory
This is perhaps a naive question, but why do we write down the Lagrangian
$$\mathcal{L}=\frac{1}{2}\eta^{\mu\nu}\partial_{\mu}\phi\partial_{\nu}\phi - \frac{1}{2}m^2\phi^2$$
as the simplest ...
4
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1answer
79 views
What are relativistic and radiative effects (in quantum simulation)?
I'm reading about Quantum Monte Carlo, and I see that some people are trying to calculate hydrogen and helium energies as accurately as possible.
QMC with Green's function or Diffusion QMC seem to be ...
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1answer
160 views
Velocity of electron in electrostatic field. Does radiation matter?
There's a voltage difference of 1000 Volts between two points 2 meters apart. An electron starts at the point of lower potential and is left to travel alone in a straight line until it reaches the ...
10
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4answers
2k views
Einstein's special relativity beyond the speed of light
Could someone with access to this paper which claims to have new transformations between frames with relative motion faster than light which are supposedly consistent with special-relativity, say what ...
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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 ...
