Relativistic Definition and 1000 Threads

  1. Z

    Relativistic vs. Nonrelativistic KE Operator question

    Hey, folks. I, on a whim today, started taking a MOOC quantum mechanics course that I have the functional math skills necessary to do but have virtually no background knowledge of quantum to start with and am incredibly rusty on stuff like PDE's; Quite frankly I'm out of my league, but the...
  2. G

    Relativistic Mass: Q&A on KE, Gravity & Particle Speed

    A : If a relativistic particle hit something, does its kinetic energy derived from base mass, or relativistic mass? B : Do we have any data, how it affects a gravity based interaction between two relativistic objects? C : Let's suppose a relativistic isotope emits two particles, one in the...
  3. P

    Relativistic acceleration transformation

    Homework Statement The given problem is that we have a rocket ship, accelerating at a constant rate of 1g (in its own instantaneous inertial rest frame) for 40 years. We must find the distance it travels in that time, as measured by an observer on earth. Homework Equations dx'=gamma*(dx-vdt)...
  4. RedDelicious

    Relativistic Kinetic Energy Derivation

    Homework Statement This problem comes from an intermediate step in the textbook's derivation of relativistic energy. It states that E_k\:=\:\int _0^u\frac{d\left(\gamma mu\right)}{dt}dx then leaves the following intermediate calculation as an exercise to the reader: Show that...
  5. durant35

    Do Relativistic Effects Impact Probabilistic Quantum Mechanics?

    Do effects like velocity time dilation and gravitational time dilation occur in probabilistic QM, are SR and GR compatible with QM?
  6. J

    Solving for velocity in relativistic momentum

    Homework Statement the relativistic momentum of an electron is 1.6 times larger than the value computed non-relativistically. What is the speed of the electron. Homework Equations Relativistic momentum p=mv/√1-v2/c2 The Attempt at a Solution Moving most of the equation around is fairly easy...
  7. B

    Deriving E=mc^2 from relativistic doppler effect

    How is E=mc^2 derived from relativistic doppler effect? I looked up on wikipedia but it seems to have some errors. https://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence#Alternative_version
  8. EsmeeDijk

    Lorentz transformation & relativistic momentum

    Homework Statement We now specify the velocity v to be along the positive x1-direction in S and of magnitude v. We also consider a frame \overline{S} which moves at speed u with respect to S in the positive x1-direction. question 1 : Write down the transformation law for p^\mu . question 2...
  9. DiracPool

    Relativistic Time & Mass-Energy Phasors

    I’m trying to get a better handle on reconciling the concept of time as it relates to the quantum wave function and the relativistic 4-momentum. To put it simply, do we look at the coefficient of the time variable in each as something separate from the time variable itself, or do we treat these...
  10. J

    How Does Relativistic Speed Affect the Force Exerted by a Train on Rails?

    I came up with this problem, which is non-trivial at least for me: Train accelerates with constant proper acceleration. When the speed of the train relative to rails is zero, rails feel the train exerting 1000N force on the rails. What force do rails feel the train exerting on the rails when...
  11. P

    Relativistic angular moment of electron in electric field

    Homework Statement Consider an electron with spin ##\vec{S}## and magnetic moment ##\vec{\mu}=-\frac{e}{m}\vec{S}##. It is moving with the velocity ##\vec{v}(t)## relative to the inertial frame of reference ##I## through the electric field ##\vec{E}##. Calculate the angular momentum the...
  12. B

    B Chemical composition of relativistic neutron star jets?

    Is there any good information about the chemical composition of relativistic jets from neutron stars? If the chemical composition of the jets was different from the accretion material it could shed light on the process that forms the jets.
  13. X

    Relativistic Centre of Momentum Frame

    Homework Statement A particle of mass m ha speed 0.546c relative to inertial frame S. The particle collides with an identical particle at rest in the inertial frame S. Relative to S and in terms of c, what is the speed of S' in which the total momentum of these particles is 0. Homework...
  14. P

    Calculating Photon Frequency From Relativistic Decay: Homework Solution

    Homework Statement Hi- I've been doing some questions and came across the following A high energy particle, traveling towards an observer with velocity v decays to produce a photon with energy E in the rest frame of the particle. Find the frequency at which this photon would be detected by...
  15. L

    Number of wheel rotations relativistic car

    A car has wheels with exactly 1m of circumference and travels at constant relativistic speed with ##\gamma = 2## in an horizontal rectilinear road between two points A and B marked on the road itself and separated from a distance of 8 m, as measured from a frame of refence which is still with...
  16. Garlic

    I Exploring Photon Mass: Is It Zero or Relativistic?

    Hello everyone, I know that the photon has zero rest mass and I know that otherwise the relativistic mass formula would not make sense. When I searched for an answer to the question "how can a particle have zero mass and still possesses energy if E=mc^2" I got an answer saying the mass energy...
  17. bcrowell

    Interesting applications of relativistic angular momentum?

    I've been working on my SR book http://www.lightandmatter.com/sr/ and its presentation of a suite of related mathematical tools such as the Levi-Civita tensor. This is aimed at the upper-division undergraduate level, although there are optional sections at the end of some of the chapters that go...
  18. M

    Looking for sources for deprecation of relativistic mass

    I am interested on the earliest reference on the deprecation of the concept of relativistic mass. AFAIR even Einstein used relativistic mass and the somehow related concepts of transversal and longitudinal force. I am trying to find a long lost article about showing all these concepts related...
  19. I

    Relativistic Doppler Effect: Explaining the Equation

    [mentor's note - lightly edited to fix the Latex] Hi there, I was hoping if someone could clear my small misconception for this equation. f' = f \left( \frac{ 1- \beta }{ 1+\beta } \right)^2 I had thought if the numerator is negative and denominator is positive that means the signal of light...
  20. Dodsy

    A simple relativistic time question

    Before continuing, I wanted to verify I have fixed the issue with the wording of my variables, and, I have seen answers for this question elsewhere. I also know I'll get full marks regardless of how I use my equations, as this question obviously isn't very focused on that, however, for my own...
  21. xpell

    (How) would we detect a passing-by relativistic object?

    Hi, I'm really curious about this one. :) Let's imagine a massive, large object with a very low albedo traveling at a slightly sub-c speed enters the solar system and passes through it before leaving on the opposite side. Please, would us earthlings detect it as it approaches, passes by and...
  22. D

    Relativistic Lagrangian and Hamiltonian for a free particle

    Hi. I am working through a QFT book and it gives the relativistic Lagrangian for a free particle as L = -mc2/γ. This doesn't seem consistent with the classical equation L = T - V as it gives a negative kinetic energy ? If L = T - V doesn't apply relativistically then why does the Hamiltonian H =...
  23. Geofleur

    Relativistic Euler Equation in Spherical Coordinates

    I just wanted to check that I am thinking about the coordinate transition correctly. The relativistic generalization of Euler's equation is (from Landau & Lifshitz vol. 6) ## hu^\nu \frac{\partial u_\mu}{\partial x^\nu} - \frac{\partial P}{\partial x^\mu} + u_\mu u^\nu \frac{\partial...
  24. Smattering

    Relativistic Speed Travel: What is the Effective Speed?

    Dear all, Let's assume I was planning an interstellar journey with relativistic speed. Being at rest on earth, the distance to the destination is ##d##. Let's further denote the proper time I will need to reach the destination as ##\tau##. Is there an official term for the effective speed...
  25. N

    Relativistic momentum (Lorentz boost) low velocity limit

    Hello, If I have a momenta pμ=(E,px,py,pz) and transform it via lorentz boost in x-direction with velocity v I'll get for the new 0th component E′=γE+γvpx why is this in the limit of low velocities the same as transforming the energy by a galilei transformation with velocity v? For γvpx i get...
  26. W

    Relativistic Particle Decay: Momentum Conservation

    A particle with mass M a rest decays into two particles a and b. I know that Ea + Eb = Mc2, from conservation of energy. But I'm pretty confused about signs in the conservation of momentum equation, and I've actually seen two versions! pa + pb = 0, so pa = - pb. But I've also seen pa = pb! I...
  27. J

    How Do You Calculate the Original Mass in a Relativistic Disintegration Problem?

    Homework Statement A body at rest in a frame of reference S disintegrates into two pieces moving in opposite directions. The masses of each fragment are 3.0kg and 4.0kg and their velocities 0.8c and 0.6c, respectively. Find the mass of the body before it disintegrated. (Answer: 10kg) Homework...
  28. I

    Relativistic Calculations for De-Broglie Wavelength

    Homework Statement At what energy will a non-relativistic calculation of the De Broglie wavelength of an electron be in error by 5%? What is this energy for a proton? Comment on your results. Homework Equations I have two (seemed to be) logical answers for this question, but with different...
  29. L

    What is the lagrangian of a free relativistic particle?

    Homework Statement What is the lagrangian of a free reletavistic particle in a electro-magnetic field? And what are the v(t) equations that come from the Euler-Lagrange equations (given A(x) = B0/2 crosProduct x) (B/2 is at z direction) Homework EquationsThe Attempt at a Solution I've got to: L...
  30. M

    Is There Enough Information to Solve the Relativistic Velocity Addition Problem?

    Homework Statement Two asteroids are approaching one another moving with the same speed speed as measured from a stationary observer on Europa. Their relative speed is 0.5c. Find the speed of one of asteroids relative to Europa. I understand how relativistic velocity addition works but am not...
  31. SquidgyGuff

    Finding relativistic force in terms of acceleration

    Homework Statement The instantaneous force F acting on a particle, as measured in frame S, is Use the formula for the linear momentum () in and the definition of the acceleration a to show that The Attempt at a Solution The professor said that this required use of programs such...
  32. P

    In a radiation dominated era, how do I show this?

    As above. In a radiation dominated how do I show this equation? http://i.imgur.com/nMwxvD5.png (It's easier for me to post the image to imgur than use latex. I know g is the relativistic degrees of freedom. I think that the scale factor a(t) is proportional to 1/t and that a(T) is proportional...
  33. S

    High Energy Textbook for relativistic quantum mechanics and group theory

    Hi, I am looking for textbooks in relativistic quantum mechanics and group theory. I have just finished my undergraduate studies in Physics and am looking to specialise in theoretical high-energy physics. Therefore, textbooks in relativistic quantum mechanics and group theory suited for that...
  34. DaveC426913

    B Electromagnets are a relativistic phenom?

    This is a new one one me: http://www.iflscience.com/physics/4-examples-relativity-everyday-life
  35. F

    Does relativistic QM obey rotational symmetry?

    SO(3) is subgroup of Poicare group.Does Relativistic Quantum Mechanics obey rotational symmetry.If it is,why we do not still keep the non-relativistic concept of angular momentum(orbit angular momentum plus spin) for relativistic concept of angular momentum,but we instead replace the concept by...
  36. F

    Electron microscope particle relativistic mass

    Homework Statement They were going to purchase an electron microscope, and wanted the electrons velocity to be as high as 25% of the speed of light after acceleration. There was a microscope at hand that had an accelerating voltage of 40 kV. a) How large is the electrons relativistic mass when...
  37. F

    Question about relativistic collision between particles

    Homework Statement Good morning-afternoon. I have been tasked with solving the next exercice; but I am unable to spot the error. Please can anyone point me in the right direction?A)Calculate the thresold energy of a photon to disintegrate in an electron and a positron in the presence of an...
  38. Luke Cohen

    Relativistic velocity problem with x and y components

    Homework Statement Two rockets leave their space station along perpendicular paths, as measured by a flight controller on the space station (see figure). The flight controller records the speeds of Rockets 1 and 2 to be 0.6 c and 0.8 c respectively. What is the velocity of Rocket 2 as measured...
  39. F

    Conservation of momentum in relativistic disintegration

    Homework Statement Hi everybody, I was studyng a photon disintegrating in one electron and one positron in the presence of a heavy atomic core; I want to find the final momentum of the atomic core Homework Equations Conservation of energy: Eγ=2me+Sqrt(Mn2+Pn2) Conservation of momentum Pγ=Pn...
  40. carllacan

    Relativistic collision and invariant s

    Homework Statement Write the invariant s = (P1+P2)2 as a function of masses amd energies of the process 1+2 → 3+4 in the center of momentum frame and on the lab frame, in which b is at rest. Interpret the result. Homework EquationsThe Attempt at a Solution For the CoM frame I have: s =...
  41. E

    Bohr model and relativistic electron mass

    From the semi-classical Bohr model of the hydrogen atom the velocity of the electron in a certain orbit can be determined. With these velocities the electron's relativistic masses can be determined. With E=mc2 the energy levels are in agreement with those from the Bohr model. I know Bohr's model...
  42. Z

    Looking for a Book on Relativistic Quantum Mechanics?

    Hello everyone! I would like you to recommend me a book for relativistic quantum mechanics. It's for an undergraduated class. thanks
  43. M

    Sending Info at Relativistic Speeds? | Doppler Effect | Horizons Photo

    I just read this article: http://abcnews.go.com/Technology/plutos-majestic-mountains-atmospheric-haze-revealed-photo-horizons/story?id=33832751 The article itself is really cool, but something at the bottom of it caught my attention. I don't know how fast New Horizons is traveling, but say...
  44. DiracPool

    Bob's Relativistic Velocity Addition: 0.9c for Alice & Charlie

    My name is Bob. I'm floating in deep space and I have these two powerful cannons that shoot my friends Alice and Charlie in opposite directions to me, one to the left and one to the right. I shoot each out at 0.9c. As I look to the left, I see that Alice is flying away from me at 0.9c. Then...
  45. M

    Analyzing Relativistic Effects on Low-Flying Satellites

    Homework Statement [/B] A low flying Earth satellite travels at about 8000m/s. For the satellite, the relativistic factor $$\gamma = \frac{1}{\sqrt{1-\beta^2}}$$ where $$\beta = \frac{v}{c}$$ is close to 1 because v<<c. Estimate by how much gamma actually deviates from 1 by expanding gamma in...
  46. S

    Little issue in Relativistic Quantum Physics

    Hey! I wanted to prove that: $$ P_L \bar{ \psi } = \bar{ \psi } P_R $$ And I want to know if I did it correctly. $$ --- $$ Here is what I did: $$ P_L \bar{ \psi } = \frac{ ( 1 - \gamma_5 ) }{2} \psi^{ \dagger } \gamma_0, $$ $$ = \frac{ 1 }{2} \psi^{ \dagger } \gamma_0 - \frac{ 1 }{2} \gamma_5...
  47. S

    Little issue with relativistic quantum mechanics

    Hey! I was working with Dirac's equation: $$ ( i \hbar \gamma^\mu \partial_\mu - m ) \psi = 0, $$ and I found that if you work with a function that depends on the momentum, $$ \psi ( \mathbf{p} ), $$ you obtain: $$ ( i \gamma \cdot \mathbf{p} + m ) \psi ( \mathbf{p} ) = 0. $$ The problem is...
  48. M

    Relativistic Transformation of Lorentz Force (E + v x B)

    Here is a problem: Imagine two equally charged capacitor plates parallel to the x-y axis, whose area is large enough compared to the distance between them that fringe effects can be ignored. The bottom plate (at z=0) is + charged, and the top is - charged. The vector field E is therefore...
  49. A

    The Relativistic Figure Skater

    Picture a large ring floating in space. It is rotating with angular momentum L. However, its radius is so large that it has essentially no tangential velocity or momentum and therefore no kinetic energy. The total energy is mc^2, with m being the invariant mass. It then begins to draw itself...
  50. H

    If the concept of relativistic mass is rejected....

    Then why did they find out it's harder to accelerate particles when they are near the speed of light? Even the lorentz equation indicates that the dimension is mass (rest mass / lorentz factor). Infinite energy is required to accelerate an object approaching to the speed of light, but what did...
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