Relativity Definition and 998 Threads

Physicists often discuss interpretations of quantum mechanics (QM), but they rarely discuss interpretations of relativity. Which is strange, because the interpretations of quantum non-locality are closely related to interpretations of relativity. The field of interpretations of relativity is...

The Lorentz covariance of Maxwell equations was known before Einstein formulated special relativity. So what exactly special relativity brought new with respect to mere Lorentz covariance? Is special relativity just an interpretation of Lorentz invariance, in a sense in which Copenhagen...

I'm struggling in the details of this exercise. Let ##S'## be the reference frame where the acceleration of the spaceship is constant, in which case we have ##u'(t')= a' t'## (since we assume no acceleration at the beginning). The rest frame of the rocket ##S## is connected to ##S'## via a...

Hello. I've recently been reading this paper... https://arxiv.org/pdf/gr-qc/0001099.pdf ...in the hope that I can begin to understand some the role of the energy conditions in General Relativity. But I'm not making much progress and so I've turned to this paper...

"their scalar product is..." why?

Alice and Bob are initially in the same inertial frame. There are 2 point test masses m1 and m2. Initially m1 is at the origin and m2 is on the positive x-axis. At time zero, m1 is instantaneously accelerated to velocity Vx in the positive x-direction. After some time, m1 collides with m2...

Let m be a point test mass. Initially m has velocity Vy in the poisitive y-direction, and zero velocity in the x-direction. At time zero, m is accelerated in the positive x-direction. In the limit as the time goes to infinity, the velecity in the positive x-direction goes to the speed of...

is there a equation that links quantum gravity and special relativity?

Summary: At this point, I am thorough with single variable, multivariable calculus, differential equations, linear algebra and basic concepts of point-set topology and tensor analysis. To learn General Relativity along-with its mathematical rigor, what are the topics I should first be thorough...

Since coordinate transformations should be one-to-one and therefore invertible, wouldn’t there be no restriction on pushforwarding or pullbacking whatever fields we feel like (within the context of coordinate transformations)?

Recently I have come into Special Relativity and specifically Lorentz transformation. Let's assume two frames A and B moving relative with speed ##v##. The position of a particle moving with respect to B is given by ##x′=f(t′)=3t′##. What is the function of position ##x=f(t)## of the particle...

Hey guys. Noob here. Question; S frame = x,y,z,t S' frame = x',y',z',t' S' is moving with a speed v relative to S and t=t'=0 when origins coincide v= 0.6c find the coordinates of x = 4 & t = 0 in S' When I use lorentz transformation, I get a negative t' and x' = 5. This doesn't make sense to...

Forgive my naive understanding of these topics. I have a layman's interest in science and follow all the popular science I can, but I'm certainly not a physicist and even my degree in mathematics is now all but forgotten in the past. But I have two questions (the other I'll post in another...

Hello, I am curious if I have this correct and if it has a name. A thin walled cylinder is spinning on its axis along its length in a closed system. It begins to draw itself in converting its invariant mass to kinetic energy. In polar coordinates ##E=\gamma_\theta m c^2, L=\gamma_\theta m...

Hello, I have a couple of questions related to reference frames in Special Relativity. Let's consider a rocket that is inertially moving towards a star with a relative velocity 0.9c. I'd like to look at this example from both the rocket's and the star's perspectives. In the reference frame of...

I have a doubt ,the thought experiment performed by einstein he thought that the clock was behind him and he is moving away from clock with speed of light what if he is approaching a clock with speed of light won't time run at very high speed

Is it complete in the sense that there's nothing further to investigate in terms of its mathematical formulation? I mean, in the sense that we don't need to introduce new mathematical tools or review existing ones for the theory.

1. An elementary particle like a photon or electron can be measured in 2 possible states - spin up or down in electron, vertical or horizontal in photons. We'll call those states state 1 or 2, and the measuring device state A or B. If for example, we measure a photon with a polarizer in State...

Something that I consider very silly, yet I try to solve relates to the relativity of simultaneity. According to SR , two evevnts taking place in different positions along the line of relative motion of two inertial observers are not simultaneous in both frames. Now, I wanted to see how this...

How much essential is it to learn concepts such as - different types of transport of vectors, like Fermi Walker and Parallel transport; - different frames (basis vectors); - tensor densities and integrations To put it another way, do they play a important role in the theory? If one for some...

I'm struggling to understand Section 2 of Einstein's 1905 paper, "The Electrodynamics of Moving Bodies." This is my source for the paper: http://hermes.ffn.ub.es/luisnavarro/nuevo_maletin/Einstein_1905_relativity.pdf In section 1 Einstein states that by definition light travels at the same...

This thread is supposed to be about finding flaws in General Relativity, but the way these people talk they sound like they have no real knowledge of GR. I was just curious if any of you guys could explain further.

So I was reading a book on special relativity and it was explaining how, if we were to go very near the speed of light, time (relative to us traveling) would slow and space itself would condense. It used the example that if we were to try and travel to a galaxy 1 million light years away, Yet we...

On a scale of 1 to 5, how useful do you think are diagrams for understanding / studying special relavity? What about general relativity?

1. I'm fine with this one, I simply calculated L = L0/γ = 5/1.2 5= 4m. 2. This is the one I'm having problems with. My approach was to say that both observers would measure the light beam to have velocity of ‘c’. Therefore, if 4m is the distance between the mirrors as observed in the frame of...

Have there been any recent developments in the attempt to unify the standard model of quantum theory with General Relativity? It appears the no progress has been made recently in string theory or loop quantum gravity.

So the universe is expanding, and galaxies are getting farther apart from one another on average. Does this motion count the same as ordinary motion, in that if a galaxy is being expanded away from us at 0.5c, that clocks in that galaxy would appear to tick slower at 0.866 the rate of clocks here?

In relativity, time is a dimension like space, a co-ordinate system. Depending on your motion, your co-ordinates shift and this leads to time dilation, simultaneity and length contraction. So, does time flow at all in relativity? Does time 'move forward'? If not, what would be different if time...

Hello everyone! Recently I saw this paper: https://arxiv.org/pdf/1304.4801.pdf ("Any nonlocal model assuming “local parts” conflicts with relativity " by Antoine Suarez). He mentions standard experimental configuration with beam-splitters and detectors. Then he distinguishes possible models...

If Earth's motion about the sun is described by General Relativity why was Eddington's experiment with the bending of starlight needed to confirm the theory? In other words, don't we see enough common phenomena in our every day experiences to confirm GR without verifying subtle phenomena such as...

The mass of an object moving at speed v increases such that $$\frac{m'}{m}=\frac{1}{\sqrt{1-\frac{v^{2}}{c^{2}}}}$$ and its apparent frequency decreases such that $$\frac{\nu'}{\nu}=\sqrt{1-\frac{v^{2}}{c^{2}}}$$ so $$\frac{\nu'}{\nu}=\frac{m}{m'}$$ but equating the energies $$ h\nu= mc^{2}$$...

Sadly, that's what all I could do.

(I swore to myself I would never ask a relativity question again...oh well) I don't know why I can't find anything about this in a search so I guess I'll just have to ask. Is a twin that takes off to Mars to stay, younger than a stay at home twin or is it ambiguous? I would think that this...

I know that it would vary depending on the type of research a specific astronomer would be doing ( Astrophysics/Cosmology research versus an Astronomer researching exoplanets ) ; but in your opinion, “how much” or “how well” should an Astronomer with a graduate degree in Astronomy know General...

Hello, I was wondering if anyone could set up and solve a classic train in a tunnel paradox from special relativity with unique values for multiple observers including time space diagrams. Thanks

I just stumbled over the following book on SRT Michael Tsamparlis, Special Relativity, Springer (2010) It's a gem! On the beginning-graduate level it explains the special theory of relativity from ground up, starting with a chapter on the math of Minkowski space and then providing a complete...

i am far from an expert in Special and General Relativity, however, my attempts to learn from this forum are hampered by the large volume of posts involving common misconceptions and lack of understanding of the material. while the members of the forums patiently [usually] help our novice and...

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Hi All, Considering a set of many many small hard balls which start colliding inside a box. The velocities of these balls being mostly greater than c/2. Is it possible, in this case, to speak of convergence to a thermal state in the same sense of ordinary thermodynamics (i.e., using...

Hi, I have been reading and watching a lot of physics lately but I have come across this problem. I have the basics of special relativity down, and it all seems clear to me. This is not in question to me. For example, I am reading a book on string theory by Brain Greene, and in it he covers...

I'm a bit confused about the idea of "Change of Signature in Classical Relativity". As I see it, a metric is just a scalar function that I make up. For example, in the x,y plane I can define the functions x^2+y^2 and x^2-y^2 simultaneously. What, then, is the significance of "changing" the...

We hear a lot of Einstein on quantum physics. Did Bohr ever say what he thought of relativity?

Summary: What is energy of proton, deuteron and alpha particle in circular motion of the same radius. Hello, I have a problem. Here is the content of an exercise: In some experiment, proton with energy of 1MeV is in circular motion in isotropic magnetic field. What energies would have...

Im just asking this general question.

Hello! I am trying to make some calculations on the Special theory of relativity over a practical example, considering the time dilation, but I may (more than likely..) be doing something wrong (probably with my assumptions). I would appreciate any comment on it. The example is that of a rocket...

Why do we use the equation ##\frac {1}{2}mv^2 = \frac {GmM}{r}## to derive potential velocity, and then put that in the Lorentz factor in order to derive gravitational time dilation? Shouldn't we be using the relativistic definition of kinetic energy -> ##mc^2(\gamma - 1)## to derive the...

We all heard about the "photo of black hole". My question is: did this image show any hints of physics beyond general relativity? I read once (not sure where) that the apparent size of black hole shadow is very sensitive to corrections to general relativity. Add some minor correction and the...

Since for the two events of Samir starting the stopwatch, and the stopwatch reaching 10.0s, Samir and his stopwatch are stationary from his own frame of reference, I said it was the proper time and that delta t0 = 10s. Then the speed of the moving frame of reference was 0.6c. I thought placing...

Hmm the mass of a hadron is an example of the verification of special relativity.The total mass of the quarks isn't equal to the mass of a hadron at rest frame.But quarks are moving very fast due to strong interaction and they gain mass (mass-energy equivalence)