Sr Definition and 480 Threads

Homework Statement In frame S , particle 1 is at rest and particle 2 is moving to the right with velocity v. Consider frame S ′ , moving relative to S , with speed u. Find the value of u such that the two particles appear in S ′ to be approaching each other with equal but opposite...

Hi, In a previous thread https://www.physicsforums.com/showthread.php?t=240886 we concluded that an observer moving away from a luminous object would see the luminosity as reduced by a factor of 1/(1+z)^n where n is 3 or 4 and z is defined as : z= \frac{\sqrt{1+v/c}}{\sqrt{1-v/c}} -1 The...

I'm going to use this thread to ask questions about acceleration in SR. I'll just ask one or two at at time. First question: How do you calculate what the world line of a rocket with constant proper acceleration looks like in an inertial frame? Assume v=0 at t=0 and v>0 after that.

I'm reading Wheeler's spacetime physics and have been doing some newbie SR problems. I thought up what shouldd be an extremely simple problem but am having trouble with the math, I'm sure one of you guys can probably help me out with it. Events A and B occur with a time separation in the...

I’m extracting here a side discussion on the application of Preferred Reference Frames from a thread on the twins paradox, so that thread does not seem to get “hijacked” by this discussion since the connection may seem thin to some. IMO the preferred frame interpretations as used in Astrophysics...

If I want to consider the velocity of distant receding galaxies which may be receding at velocities close to the speed of light can I use SR? I know you are not suppose to use SR with when velocities are close to the speed of light. If a velocity is due to universal expansion does that make a...

Since SR physics has considered motion strictly as the separation of bodies, no longer can a body move through space except with reference to another body. Consider an infinite number of frames (A, B, C, ... A1, B1, C1,...An) with common x axis. All move near the speed of light relative to...

http://http://arxiv.org/abs/0803.2701v1" is a new, well-written explanation by R. J. Cook and M. S. Burns as to why the accepted physical attributes of GR are entirely frame-dependent. This concept is fundamental to understanding GR. Jon

Homework Statement a ufo travels from one planet to another (distance measured 384000km) at v=0.8c. 1)How long does the trip take according to observer on planet left? 2)How long does the trip take according to observer in ufo? 3) What is the two planets distance measusured my...

I need to learn optics, SR and continuum mechanics for my physics qual exam in June. Can anyone suggest some books that would be appropriate for self study?

Consider the limit of the function mcc/sqrt(1-uu/cc) for u=c. (m rest mass, u speed of the particle with rest mass m relative to a given inertial reference frame. Please tell me what is its physical meaning. Do you see there a connection with the energy of a photon? Thanks in advance for...

Homework Statement Referring to the drawing attached: Two rods of the same length ( say 3 m ). Rod A has a velocity of v = 0.866 c in x. Rods are very close in y. The drawing is taken from the point of view of rod B. 1 - Is the drawing correct ? 2 - Could we say that the right ends of...

Einstein derived E=mc2 using his SR in 1905...My question is 1. can E=mc2 be derived only using SR? 2. Even before einstein some(poincare,de pretto) have arrived at mass - energy equivalence relation... does this mean E=mc2 can also be derived without SR?

Hi all I was recently told that certain postulates of SR are equivalent or one can be derived from the other. Namely 1) The speed of light in vacuum is constant and is independent of the speed of emitting body; 2) The speed of light is impassable limit; I did some search and found quite...

A spring pushed or pulled with a force F is elongated by x according to Hooke's law: F = -k . x where k is a constant of the spring. Does the k constant changes when seen from a reference frame at rest ? The spring is moving. This comes from...

I realize that the understanding of physics and the perferred description or mathematical representation of our understanding evolves over time. So I have a feeling that the answer to my question is strongly a mix of history and physics. Please, when at all possible add some of the historical...

I quickly read the followoing IEEE paper: http://www.atomicprecision.com/blog/wp-filez/Thim%20-%20Absence%20of%20the%20relativistic%20Doppler%20effect%20...%20.pdf The author claims he proved that he invalidated experimentally the SR prediction of a transverse Doppler effect for...

Do accelerated observers also see the same constant speed of light as inertial observers? How do we transform to an accelerated frame? For simplicity, I mean a constant acceleration, constant in direction and magnitude. By acceleration I mean the second derivative with respect to lab time...

can someone recommend one? i have spacetime physics by wheeler and whoever else and though it's decent and self consistent, it proves too many things by analogy rather rigorously. preferably something that doesn't use any of the common thought experiment like the clock on the train or something...

If x=u(x)t p(x)=u(x)t k(x)=uf and probably many other such equations, then why it is not enough to derive the LT for x and t and to mimick the transformations for all the others? Would that obscure or reduce transparence. Would that show the kinematic origin of all the relativistic effects...

Is this possible?

2nd postulate of SR says that speed of light is constant in all inertial frames. And it exlains all SR. but How to prove this? I have seen that michelson-morley experiment can be explained by this. Is this exp is only reason?:confused:

I had some spare time and I wanted to compile a document that contained all the mathematical steps to obtain E=m'c^2. Anyway, I have written this PDF. If any of you have spare time, can you please look over my document and criticize it?:smile: Also, if this place is inappropriate to post this...

Homework Statement Two particles, A and B, have the same rest mass, m. Suppose that, in O, A has 3-velocity (V,0,0) and B is at rest. The particles collide elastically at the origin and after the collision A has 3-velocity (a \cos(\theta), a \sin(\theta),0) while B has 3-velocity (b \cos(\phi)...

Homework Statement A particle leaves the spatial origin P of O at time t=0 and constant velocity. After a time t as measured by O, a second particle B leaves P at a different constant velocity and in pursuit of A. B catches A after proper-time t as measured by B. Show that the rapidity of B...

From http://www.us.oup.com/us/catalog/general/subject/Physics/Relativity/?view=usa&ci=9780198567325" I learn that the fundamental identity c^2\text{d}{t'}^2 -\text{d}{x'}^2 -\text{d}{y'}^2 -\text{d}{z'}^2 = c^2\text{d}{t}^2 -\text{d}{x}^2 -\text{d}{y}^2 -\text{d}{z}^2 relates co-ordinates...

Long ago I accepted that the speed you move through time is personal, but I've always wanted to really understand it intuitively. I think I'm almost there. Suppose me and my ghost are in the same place initially. Now I take off running in a direction, but my ghost remains behind. Since I'm...

I'm trying to understand SR better however I think I've got myself confused in some ways. Firstly, I can't think of exactly why a mechanical wave like sound should follow gallilean relativity (besides that F = ma is used on the "mechanical pieces" of the wave and we know F = ma obeys...

As I mentioned a while back I was starting a new project so I wouldn't be posting much until I was finished. The project was for me to take all my files (all physics articles) from the two draws in my cabinet and scan them and place them in PDF files. That work is now complete. The list of...

I read a statement on another message board the SR forbides BHs and GR demands them. Does SR forbide Black Holes, if so, why?

Hi all, I would really appreciate any explanation on how these two are interrelated. Thanks. Preferably in simple terms. Nish

It is possible to draw world-lines of the two twins in the non-accelerating one (A) frame of ref. The aging of the other (B), with respect to the first, is evaluated integrating its proper time differential (and comparing it with A's proper time). My question is (certainly already asked): is...

Hi! Just as I thought I was getting a pretty good grip on relativity, I got thrown back to square one. Please straighten out something for me by taking a role of a passer-by in my thought experiment. First, I read that according to Special Relativity (SR), observers in two moving inertial...

we have two inertial frames, S and S' where S' is moving with speed v along the x axis. here are a few questions about these frames: 1. if two events occur at the same point in some inertial frame S, prove that their temporal order is the same in all inertial frames, and that the least time...

Homework Statement A train passes a platform with velocity v. Two clocks are placed on the edge of the platform separated by a distance L and synchronized relative to the platform inertial system. Clock 1 reads 4:00 when it coincides with the front of the train, and clock 2 reads 4:00 when...

Alright, I'm having a bit of trouble understanding time dilation. My biggest concern is in how an observer in a frame will see all other frames at different relative speeds moving slower. I've been trying to show it mathematically, but haven't had the luck yet.

Hey guys Ok, after my last whimsical attempt at expressing my lack of understanding regarding c being constant in all reference frames, i did some digging and have come back equally bewildered but with some more ammo. Ok, so as far as i know it goes like this. Galilean relativity states...

"Hidden variable" in SR and GR Relativity??.. My question is, since we live in a 3-D world, what would happen for an "alien" living on a 4-D world??..if we suppose that space-time has only 4 dimension, and that after a Wick rotation then X_{0} =it then what we think is just a time component...

I think that in Special Relativity, the drift of the perihelion can be calculated by cumulating elementary Lorentz transformations along the (Newtonian, unperturbed) trajectory. I read that the result of this calculation is much smaller than the experimental value. It is also well known that...

Okay, I realize that there are difficulties in combining the theory of GR and quantum mechanics, but I thought SR and quantum could be combined alright (relativistic quantum field theories, etc). If that is not correct, please let me know as it makes the rest of my questions pointless. My...

Hello I'm trying to picture various light based experiments as described from a frame that is in motion with respect to the experiment devices. For instance the reflection of a photon in a light clock: the atoms (and their fields) that constitute the surface of the mirror are squashed. How...

Hello, This may look like a homework, but it is rather a refresher for my hobby-time. I just found a nice collection of exercices: http://uk.arxiv.org/PS_cache/physics/pdf/0605/0605057.pdf". The exercise 2.2 is funny: Sure this is no flaw of SR ! What's the explanation? What are the...

Is SR "real"? What I mean to say is that as SR predicts time dilation, do the biological processes also slow down? Suppose A and B are two twin brothers.one of them(A) goes for a space tour in a spaceship with a velocity comparable with c, while the other(B)remains on earth. Clearly, for B...

The correct derivation of magnetism as a relativistic side effect of electrostatics: http://chip-architect.com/physics/Magnetism_from_SR.pdfI've claimed quite a few times here that Purcell's derivation is not correct. Making claims is one thing. Better is to pinpoint exactly what is wrong, and...

In http://members.tripod.com/conduit9SR/SR3.html" example of relativity with the space trains, if we are in train B (were will observe train A is moving), then why can't the events be observed simultaniuosly? If we ARE in the middle of B, then the light SHOULD take the same time to reach from...

What book(s) would you all recommend for learning about these two theories? I have limited math knowledge; most of the equations I see look like a greek sentence to me. Is it even possible to really comprehend relativity without the math? I keep asking questions that turn out to be rather...

This is something that arose out of a section in Richard Mould's Basic Relativity. He begins SR with his so-called "Physical Threorms (PT)," which are gedanken experiments used to show the effects time-dilation, length-contraction, and the concept of simultaneity in relativity, in that order...

I don't have any SR texts to hand, and was wondering if someone could prove the following conjecture: all particles with positive rest-mass must move at speed less than c. I understand that there are a multitude of physical reasons that support the above conjecture. But is there a good...

From SR to GR in an "easy" math (and physical) way Hello..i know that for example to go from Newtonian to SR you take: \frac{du}{ds}=0 \rightarrow \nabla _{u} u=0 My question is ¿is there an "easy" form to go from SR to GR in the form: \nabla _{u} u=0 \rightarrow \nabla R_{ab} =0...

Suppose I am an observer stationed at the origin of frame O, watching a frame O' pass by me at some velocity u. If I look at the clocks stationed on various different positions on the frame O' (at some fixed instant on my watch), will all the clocks show a different time?