Lorentz Definition and 1000 Threads

I've had my second class of Modern Physics and I have some "obvious" doubts that many of you certainly had, although I didn't find anything answering the first doubt on a quick google search. 1)Say I am in an inertial reference frame. I can see that any photon going around me do it at a...

Hi. My question is how the Lorentz magnetic force F=q\vec{v}\times\vec{B} is derived? Is it due to magnetic moment of charged particles? If the moving charged particle does not have magnetic moment (due to spin, so the torque on the particle is zero) how the magnetic force changes its direction...

This is related to the thread on the meaning of diffeomorphism invariance but is adressing a distinct point (at least I think so, but I may be proven wrong). As Rovelli discusses in his book, the action of the Standard Model coupled to gravity has three types of invariance: under the gauge...

In Einstein's book Relativity he provides a derivation of the LT. link here http://www.bartleby.com/173/a1.html" In step 3 he brings in constants λ and μ and now I am lost. In the equation (x'-ct') = λ(x-ct) - isn't this the same as "zero = anything X zero"? How did λ and μ get...

I am trying to establish whether the force defined by the Lorentz equation below is invariant under the Lorentz transforms: [1] F = F_E + F_B = qE + qvB In the context of this equation, [q] is moving with velocity [v] such that it is acted on by both an electric E-force and magnetic...

I am wondering about the order of operations concerning the Lorentz transformation of fields and the superposition of fields. I was given a problem: Two positively charged electrons start at the origin and then travel along the x-axis at a constant speed v in opposite directions. Calculate...

Hello, as far as I know a "fractal", by definition should manifest self-similarity or at least statistical self-similarity. This usually takes the form of scale invariance. Can anyone point out where is the self-similarity in the plots of Lorentz attractors? Thanks.

Iv just been reading a physics textbook and i feel iv completely missed something. It may help to draw a diagram and to read the thread slowly. Sorry if it is a little thick. My understanding of Special Relativity is that it allows two seemingly conflicting principles to co-exist, these being...

Homework Statement A spaceship of proper length Lp = 400 m moves past a transmitting station at a speed of v = 0.76c. At the instant that the nose of the spaceship passes the transmitter, clocks at the transmitter and in the nose of the spaceship are synchronized to t = t' = 0. The instant...

In special relativity, velocity dependent forces transform. Let us then consider frictional forces, such as drag, which are velocity dependent in the first order. Do two observers moving relative to a third body measure different frictional effects?

I'm studying General Relativity and facing several problems. We know that energy-momentum must be Lorentz invariant in locally inertial coordinates. I am not sure I understand this point clearly. What is the physics behind?

In electrodynamics, the Coulomb gauge is specified by \nabla \cdot A=0 , i.e., the 3-divergence of the 3-vector potential is zero. This condition is not Lorentz invariant, so my first question is how can something that is not Lorentz invariant be allowed in the laws of physics? My second...

My question is: why does Lorentz contraction happens? I have a understanding of this but I don't know if it's correct, so I'll tell what I understand, if I'm wrong please correct me... Suppose we have two observers A and B. If I say B is moving with respect to A then time is slower to B...

Homework Statement Q1 http://www.maths.ox.ac.uk/system/files/private/active/0/b07.2_c7.2.pdf Homework Equations The Attempt at a Solution How do I do the final bit that lead to the discrepancy and why does this occur? I have no idea where to begin.

Homework Statement Muons, which have a half-life of 2 x 10-6 s, are formed in the Earth's atmosphere at an altitude of 10 km. If they travel normal to the Earth's surface, and one half of them reach it before they decay, what is their velocity? Homework Equations Lorentz...

Einstein is commonly regarded as the primary inventor of special relativity. I'd like to trust the collective wisdom of others, but I never feel fully convinced. The argument is typically "Though people like Lorentz and Poincare have worked out most of the math it's only Einstein who realized...

If an observer O' see a body that moves with constant velocity Ux along the axis x' in a positive direction. What is the velocity VxO of body observed by O? That is all the information I have. Can you help? :blushing:

I'm having a bit of trouble understanding what exactly the lorentz force is. In this diagram here [PLAIN]http://img7.imageshack.us/img7/7065/helicinbfld.jpg I know its the force that's keeping the proton in that helicoidal trajectory so I can see its perpendicular to the direction of the...

Homework Statement Consider a particle of mass m that carries a charge q. Suppose that the particle is under the influence of both an electric field E and a magnetic field B so that the particle's trajectory is described by the path x(t) for a\leqt\leqb. Then the total force acting on the...

I was thinking that if i have for example a boost in the direction of x, then the boost should be equivalent to an hyperbolic rotation of the y and z axes in the other direction. I don't know if it's true or not. Then I want to know if somebody knows this result or why is false? I was...

Using the Lorentz transformation, at what speed relative to speed of light c must you travel so that your length along the direction of motion is seen to decrease by a factor of 2? For this speed, hwo much would your mass be increased? Please show steps, I'm confused with this question!

From this link http://en.wikipedia.org/wiki/Introduction_to_special_relativity" In the section entitled "Invariance of Length: The Euclidean Picture" the article discusses how rotations within an n-dimensional space keep length invariant. However, if you rotate and object into a higher, n+1...

I'm studying for my modern physics final and this problem is giving me trouble; Q: In a frame S, two events have spatial separation deltaX= 600m, delta y and delta z = 0, and a temporal separation deltaT= 1micro second. A second frame S' is moving along the same axis with nonzero speed v...

Homework Statement Question is E=(x,y,z) B=(x,y,z) v=(x,y,z) (in vector form) For all E,B,v find v(t) and r(t) v and r of course have their vector arrows. Homework Equations F=ma= qE + qv x B There is a hint to take second derivatives across and some terms will clear up. I was thinking more...

As I understand it, Lorentz Contraction states an object "contracts" relative to it's velocity to an observer. So at a high velocity of speed, the meter stick (carried by the object moving relative to the observer) appears to contract (to the observer) and the observer measures less distance...

Let L_w be a Lorentz transformation between to systems that coincide at t=0(paralell axes assumed) and with relative velocity w along x_1. If L_u is the Lorentz transformation when the relative velocity u is in any direcction then we have that L_u=R_2 L_w R_1 where R_2 and R_1 are sapce...

I was reading a section on lorentz boosts and i need some help understanding what they did: the book starts off by defining the line element dS where: (dS)^2 = -(CΔt)^2 + dx^2 + dy^2 + dz^2 then they say: "consider the analogs of rotations in the (ct) plane. These transformations leave...

http://en.wikipedia.org/wiki/File:Magnetischer_Kreis.svg The attached image shows a magnetic circuit with a small air gap. The magnetic material on each side of the gap is attracted to the other side. I've seen the magnitude of the force calculated based on principle of virtual work...

Homework Statement Hello, Consider a rod of proper length l_{0}. Prove/Show that there is no length contraction if an observer moves perpendicular to the direction of the rod. Homework Equations l = l_{0}/\gamma where \gamma is the usual relativistic vector The Attempt at a...

I'm trying to show that the generators of the spinor representation: M^{\mu \nu}=\frac{1}{2}\sigma^{\mu \nu}=\frac{i}{4}[\gamma^\mu,\gamma^\nu] obey the Lorentz algebra: [M^{\mu \nu},M^{\rho \sigma}]=i(\delta^{\mu \rho}M^{\nu \sigma}-\delta^{\nu \rho}M^{\mu \sigma}+\delta^{\nu \sigma}M^{\mu...

Homework Statement 3. At what speed (measured in units so c = 1) must the train be moving in order for the points(X,T) = (1,1) and (X,T) = (5,2) to be simultaneous in the (X',T') coordinate system? Homework Equations Disclaimer: I'm not actually in a physics class, I'm in an elementary...

Preface: If a bar magnet is cut in half, we are left with say N-S--cut--N-S allinged along the z axis. Then the S and N ends are attracted to each other. This attraction is due to the "fringing" or non-uniform B field of the poles. That is the component of the B field that is normal to the...

Lorentz transformations ("synchronising" reference frames?) Homework Statement A particle moves from (x,y,z,t) = (0 m,0 m,0 m,0 s) to (1 m,1 m,0 m,10 ns). i. What is the speed of the particle in this reference frame? ii. What is the speed of the particle in a reference frame moving...

I'm a bit confused about how the Lorentz Force (as a law) stands in relation to the laws of Maxwell (independent of each other? dependent?). There are two concrete examples I can think of where they interfere with each other: 1: Lorentz Force & Faraday's Law of Induction Imagine a...

Good evening, As an effort for trying to understand Lorentz transformations, I'm trying to use them to derive the "length contraction" result. Consider two reference frames, O (non-primed) and O' (primed), moving with respect to each other with a velocity v. Consider them to be under...

The existence of entropy in gravity implies that there are microscopic degrees of freedom in space that carries the entropy. This implies space is discrete. Discrete space breaks lorentz invariance, which has been strongly constrained by both FERMI and thought experiments. String theory...

Hi, this is a question from a practice paper I have. I can't think how to do this. As far as I'm aware this has to be assumed to derive the Lorents transforms, so it must be by definition true, making the question pointless. Does anyone have any thoughts or suggestions on this? Regards, Pete

I have a question which i believe is pretty standard, spaceship traveling towards space staion at 0.80c it fires a missile at 0.40c what is the speed of the missle observed by the space station I'll tell you where I am at; I have set 2 inertial frames. A being that of the space station and...

Homework Statement Ok so I know how to prove Time Dilation using the Lorentz transformation... My problem is that I don't see why one couldn't use the Inverse Lorentz Transform and come to the opposite result as follows: Time period in rest frame S: T = t2 - t1 ILT: t = $(t1' + B/c...

It is known that in a current carrying wire, exposed to a magnetic field, the wire will experience a force equal to the product of the field, the current and the length of the wire (where the direction of the force is orthogonal to both the field and the direction along the length of the beam)...

Hi guys Can one prove the identity \frac{\epsilon}{x^2 + \epsilon^2} \underset{\epsilon\to 0^+}{\to} \pi \delta(x) or is it just intuitively clear (by looking at a graph)?

It seems that the common approach to obtain the equations for the Lorentz transformations is to guess at its form and then, by considering four separate situations, determining the values for the constants. From these equations, things like time dilation and length contraction can be worked out...

I find Maxwell's equations insufficient and superfluous having the Lorentz & Coulomb's force equations. As far as I see magnetic (Lorentz force) and electric (Coulomb's force) interaction is best defined by these two equations themselves, and although Maxwell's equations can describe quite a few...

Hi, If M^{\mu\nu} are the generators of the Lorentz group, i.e. they obey [M^{\mu\nu}, M^{\rho\sigma}]=i\hbar(g^{\mu\rho}M^{\nu\sigma}-g^{\nu\rho}M^{\mu\sigma})+...(1) and L^{\mu\nu} is defined by, L^{\mu\nu} := \frac{\hbar}{i} (x^{\mu} \partial^{\nu}-x^{\nu} \partial^{\mu})...

Hi there. I have just started to read about the Relativity part of Maxwell's equations and would like to get some clarification from anyone here were I can discuss and/or get answers in a more " every day life " way of writing. 1) What is the most simple way of transforming Maxwells...

How can I convince myself of the following statement: If x2<0, there exists L orthochronous Lorentz tranformation such that: Lx = -x My concern is this: If for example, we take xµ=(1,0,0,0), then Lx in component form is: Λµβxβ=Λµ0x0 =(Λ00, Λ10, Λ20, Λ30). By definition, if it is an...

I have a two component Weyl spinor transforming as \psi \rightarrow M \psi where M is an SL(2) matrix which represents a Lorentz transformation. Suppose another spinor \chi also transforms the same way \chi \rightarrow M \chi. I can write a Lorentz invariant term \psi^T (-i\sigma^2) \chi where...

Is there a difference between the Lorentz velocity transformation and the relativistic velocity addition? They give the same result...

Homework Statement A pi+, produced by a cosmic ray, has an energy of 280MeV in the laboratory frame S. It undergoes a decay: pi+ ---> muon+ & muon-neutrino. The muon produced continues to travel along the same direction as the pi+ and has a mean lifetime of 2.2mirco seconds in the muon's...

Heisenberg's uncertainty relations are not covariant under Lorentz transformation. That means they don't have the same form in any inertial frame. So, how to modify these relations to leave them invariant in form under a Lorentz transformation ?