Sr Definition and 480 Threads

Suppose I have a disk that is 100,000 km in diameter. I attempt to rotate it at 1 revolution per second. Am I unsuccessful because the material on the outside edge would have to travel faster then light or am I successful because length contraction at the outside edge reduces the...

I would like to ask if anybody knows about some analysis of this part in Einstein's derivation of SR where he gets rid of unknown scaling function φ(v): "From reasons of symmetry it is now evident that the length of a given rod moving perpendicularly to its axis, measured in the stationary...

Hi all, So, I've been trying to get my head straight about a luminiferous aether and have been reading about the experiment of Michelson and Morley. It seems there are many factors of SR that get in the way of this experiment actually producing any plausible results. I assume the whole point of...

Hi all, I'm currently a stage 1 Physics student at uni; and in the process of learning Special Relativity. I was reading my textbook and came across this in the Time and Space section: Suppose an observer in frame S measures two flashbulbs going off at the same time t but at different...

I don't think this would ever come up on any of my tests in high school, but how would one answer a question combining the Broglie Wavelength of a particle and Special relativity? Are they cumulative? BW : λ= h/mv

I'll try to be as specific as possible with my question. From my reading of SR I understand that an object that is moving relative to me will be contracted in the direction of its motion. I have no issue with that and I accept it as a fact. Would I be right in thinking that there is also length...

Neutrinos are thought to be particles with mass. So they aren't even supposed to be traveling at the speed of light to begin with, let alone travel faster. They would have to have some type of imaginary mass in order to do so. So what do you guys think will have to be modified in SR and GR if...

This is a continuation of https://www.physicsforums.com/showthread.php?t=526249", now that my confusion on Thomas precession has been clarified and my root question has been shown to not stem from this effect. In classical mechanics for any inverse square force, \vec{F}=-\frac{C}{r^2}\hat{r}...

2 space stations are separated by a distance of 10 light years and are at rest wrt each other. I set off from A to B at a constant velocity of 0.5c. As I understand it, 20 years would pass for people on the space station but when I arrived at the second station I would have only aged about...

http://books.google.com/books?id=qhDFuWbLlgQC&lpg=PP1&pg=PA11#v=onepage&q&f=false" Until he arrives at eq. 1.5 I don't understand the steps, can anyone explain it? thanks

SR leans more toward direct observation rather than explanation, which is fine, mostly resulting from experiments with aberration and M-M type experiments, but I would like to know more about the how's and why's involved. I have come to some of my own conclusions, but will only ask questions...

hello One of the postulates in SR is that the speed of light in vacuum is constant for all observers. Is there a theory in which this is derived and is not a postulate? Thank you.

I assume in an SR example of a propagating sphere of light from a pinhead size event that its propagation symetry is independent of the frame which created it. The point on the frame which created the event must be somewhere within the sphere. Use three photons on the sphere to create a...

I've been comparing various books, including these: Mermin, It's About Time Takeuchi, An Illustrated Guide to Relativity for possible use in a gen ed course on relativity. It's cool to see that there are so many books out there now that aren't just replaying Einstein's 1905 postulates with the...

Homework Statement http://i.imgur.com/VVVAl.png Homework Equations K = mc^2/(1 -v^2/c^2)^(1/2) - mc^2 E = ((pc)^2 + (mc^2)^2)^(1/2) The Attempt at a Solution I don't know how to find the kinetic energies of the particles in the center of mass frame. I thought that they should just...

This thread https://www.physicsforums.com/showthread.php?t=500493 has led me to the following question, which probably has an obvious answer that I'm just not seeing. The Lorentz transformation L depends in a simple way on the rapidity φ, and it scales according to L(kφ)=L(φ)k. What is to stop...

a nice catch by atty ,what do you think. http://arxiv.org/PS_cache/arxiv/pdf/1105/1105.3930v1.pdf The emergence of Special and Doubly Special Relativity Authors: Petr Jizba, Fabio Scardigli (Submitted on 19 May 2011) Abstract: In a previous paper [Phys.Rev.D82, 085016(2010)] we...

Homework Statement This is a special relativity question: Two gamma rays of identical energies E collide with an angle \theta between their velocities. Show that positron-electron pair creation is impossible in the limiting case \theta=0. Find the minimum \theta value for p-e creation to...

Why is it that when we combine SR with QM we are lead directly to the multiparticle picture. I know about the standard textbooks, I need to know EXACTLY why? What is it in SR that produces the multiparticle picture.

I am trying to ascertain whether the 4th paradox proposed by Zeno (the Stadium) can be used to refute the idea of quantized space and whether such conclusion is affected by SR. Let us assume: - Two equal blocks moving towards each other: block A from left to right and block B from right to...

SR and QED: how? how the particle moving at a speed near to that of light interact to it's surrounding,considering the very fact of it's time dilation? what i mean to ask probably is that will it b possible for this particle to create another one from it's energy and still manage to throw...

In CM there is this equation of motion for ciruclar orbits: F=k/r^2=m*v^2/r, where k depends on the force involved. I know this gets complicated in GR, but is there a simple expression for circular orbits in SR, what happends to the m*v^2/r ? If the forces are only electromagnetic, does k/r^2...

Probably this has an easy answer but I can't see it just now, according to the principle of relativity we shouldn't be able to tell based on physical experiments if a body is at rest or in a uniform velocity, but in the case of charged objects we seem to be able to differentiate it simply by the...

This topic has been dealt with many threads, in various aspects. I want, in this thread, to set up an example focusing in on all related issues and, hopefully, centralizing best answers and explanations. Example: We have a large black hole with a star orbiting it with an substantially...

Hi, when we say the distance in the direction of motion shrunks and time slows(sorry for my grammar), do we say that if we were in the moving reference frame(relative to us) the length we measure from our stationary frame(relative to the other one) gets bigger and same logic for the time slowing...

Hi my question is What is the molar mas of: Sr(NO3)2 1 mol Sr ((87.62 g Sr)/(1 mol Sr)) = 87.62 g 2 mol N ((14.007 g N)/(1 mol N)) = 28.014 g 6 mol O ((15.999 g O)/(1 mol o)) = 95.994 g The molar mas is (87.62 g + 28.014 g + 95.994 g) = 211.628 g

N. David Mermin has an interesting geometrical approach to SR that I came across today. He seems to have described it in the following places: 1. Mermin, N. David, "Space-time intervals as light rectangles," Amer. J. Phys. 66 (1998), no. 12, 1077 2. a popular-level book called "It's About Time"...

Homework Statement Not really a homework/coursework problem, I'm just trying to make sense of some class notes from our chapter on special relativity. I'm trying to find the expression for electromagnetic wave propagation in a reference frame S' that is moving at a constant velocity with...

A few weeks back I posted about a test by C. Alley in the 1970's of Einstein's famous goof in predicting that a clock would run at a different rate at the poles than at the equator. Alley apparently was never big on publishing his results in journals, but I requested a conference proceedings via...

I am having difficulty working out one of the steps in Einstein's original SR paper, in the Section entitled "Dynamics of the Slowly Accelerated Electron". Einstein describes an electron in motion in an electromagnetic field. Its equation of motion in a rest frame K (not moving with the...

A rod moves along x-axis with speed u and has length L relative to Inertial Frame S. What is its length L' relative to the other inertial S' that moves with speed v with respect to S. I know the famous length contraction formula L=L' * sqrt(1-square(v/c)) but I confuse how to include...

I would like to start a brain storming thread, listing all the possible complications that would arise from NOT having SR. SR is what makes our reality what it is, so I expect that without SR, some serious complications would arise. Surely SR, is not just some insignificant nuance of reality...

Ideal clocks are taken from event A to event B along various worldlines. then that the longest proper time for the trip is indicated by that clock whcih follows the straight worldline. How it can be showed. thanks

Hi, I have been wondering if there is a Lorentz-invariant quantity that satisfies the definition of a metric for space-time. The space-time interval s2 = t2 - r2 [where r is the vector (x,y,z)] does not satisfy the requirement for a metric m that m(t1,r1, t2,r2) = 0 if and only if (t1,r1)...

LET, Lorentz ether theory, is identical to SR but invokes an ether as the cause of length contraction and time dilation with motion through the ether. With it, there are no strange conceptualizations according to each observer's own particular reality for what they observe of other frames, but...

So I've been trying to find an equation that will represent total time dilation. I've looked through a couple threads and it seems the consensus of the threads I've seen on the topic say that total time dilation is the product of time dilation due to velocity and gravity. But I'm not clear...

Three simple experiments put to question Einstein's Special Relativity interpretation. It has nothing to do with the formulas. Formulas work pretty well; the BIG problem is interpretation! 1.The most recent particle collisions at CERN: Two Proton Beams at 3.5 TeV, traveling in opposite...

This is a conceptual question in special relativity. Let's say we have 2 cyclists riding parallel to each other, separated by a distance D, at a constant velocity directed along the x axis, v. Cyclist A has a laser, and he points it at cyclist B and presses the button so that a short pulse...

This is the continuation of a discussion in https://www.physicsforums.com/showthread.php?t=431068". Where does SR end and GR begin, in today's textbooks (not internet forums)? Do accelerating frames (coordinate systems) belong to also to SR, or is GR needed? I say that they belong solely to...

This is a continuation of the thread Derivation of proper time of acceleration in SR We have definitions for proper time, proper speed, proper acceleration, coordinate speed, coordinate time, and coordinate acceleration. 1) What is the definition ofproper distance? 2) If proper...

I know that in GR center of mass is not well defined. Whats about SR? Is a worldline of center of mass observer-dependent or not? P.S. As rest mass is not conserved, as I understand, it makes sense to talk about center of relativistic mass = center of energy?

This is a carryover from a previous thread: https://www.physicsforums.com/showpost.php?p=2875138&postcount=68 Sports Fans: I am familiar with the Minkowski equations and the Lorentz transformations in one or two dimensions: A) In algebraic form (1) t2 - x2 = t'2 - x'2 (2) t' =...

To yuiop: Consider an object of mass m0 which, subjected to a constant force, accelerates at a0 initially. Initially, the velocity of this mass is zero but then picks up as this force is applied. By the relativistic momentum equation, a = dv/dt = a0\sqrt{(1 - v^2/c^2)}...

I'm learning about special relativity in its differential geometry formulation. I don't understand how special relativistic effects can be derived from the Minkowski metric. It isn't obvious to me where relative velocity comes in, or why this makes things look different. Can somebody explain how...

Hi All, Let me see if I can put my doubt in words appropriately... Imagine a source of EM radiation, say a laser beam, and suppose you are running against the laser's direction, i.e., photons go to positive x and you to negative x direction, for instance. From the POV of SR, light does...

I just had a strange thought: In section 23 of his popular book, "Relativity - The Special and General Theory", Einstein explains why a clock on the edge of a rotating disk will run more slowly than one at the center, and then says, "thus on our circular disk, or, to make the case more...

A friend of mine posed this SR paradox to me a few weeks ago and I was unable to come up with a convincing answer (nor have I been convinced by any I've heard!). The problem is as follows: Assume we have a train track which has certain gaps in it. At rest, the train which moves on the track is...

Acc. to QM no two particles can be in the same state at the same position at the same time, but how does that reconcile with SR where two observers do not agree on simultaneity? Do some observers see baryonic stuff violate this postulate?

I just found out that you can do acceleration/deceleration problems in SR. I didn't know that. The problem I was thinking of was the classic Terence/Stella problem of recent fame on this Forum. See this post by Jesse M who solves this for constant velocities...

Let's say you are receiving photons from all over. The velocity of each photon coming to you is c. If you moved at velocity v compared to your initial inertial frame, without SR you would say that photons going the same direction as you are moving at c-v, while the photons going the opposite...