Relativity Definition and 998 Threads

Homework Statement not sure fully sure on this equation Homework Equations f=fo√(1±v/c)/(1±v/c)[/B]The Attempt at a Solution is it just the relationship between the observed frequency and the proper frequency or something? [/B]

Homework Statement Two identical particles of mass m travel towards each other at speed v; they combine and form a single new particle. By employing conservation of momentum and conservation of energy, what is the mass of this new particle in Homework Equations Relativistic momentum and total...

Hi, I am a Physics graduate and I am VERY mathematically inclined. (This does NOT mean I know a lot of math. My curriculum focused on experimental physics - which left me with a very keen desire to study all the mathematics involved - so I do need to start from scratch.) I would like to study...

We have got some SR work to do, however we have only had 1 introductory lecture. I have a problem with one of the problems. Question: A rod of 1m parrallel to the x-axis, travels at un-relativistic speeds at 45 degrees. It passes through a slit - also parallel to the x-axis - that is 1.1 meters...

Hello! What book should I use as an introduction to General Relativity? Something that includes an introduction of the math behind GR (tensors for example) would be much appreciated. Thank you!

We know that the OBSERVED mass increases as the objects approach near to the speed of light. I was wondering that how does a stationary observer observe an increase in mass of an object which is traveling far away from it. I mean mass is a sensation, how it is observed by a stationary observer?

I always hear that the two 'don't match' and disagree, but never in what... Someone mind explaining?

Homework Statement You are on Earth as a spaceship flies past at a speed of 0.99c relative to the earth. A high-intensity signal light on the ship blinks on and off, each pulse lasting 2.2 × 10^(−6) s, as measured on the spacecraft . Your laboratory on Earth has a length of 56.4m. How long...

I thought of this 'paradox' which is somewhat similar to the twin paradox but can't be explained by a lack of symmetry etc. It is very similar to many paradoxes I have heard before of which the resolution is known (which is why I am mostly sure this can be resolved) Bob is looking through his...

Hey guys, Can you please refer some good books to refer to in studying relativistic Electrodynamics (introductory parts), covering the Maxwell's equations in tensor form the L-W potentials and other aspects. FYI am just a beginner in relativistic Electrodynamics. Thanks for the help.

If we have come to realize that energy conservation is not the most general conservation law in our spacetime, isn't it odd that we don't have a simple name for the "real deal"? I bumped into this thought through Noether's theorem, which relates symmetries in fields to conservation of all kinds...

Homework Statement Hi, I have this problem: For motion under a pure (rest mass preserving) inverse square law force f = −αr/r3 , where α is a constant, derive the energy equation γmc2 − α/r = constant. Homework Equations E = γmc2 dE/dt = f.u for a pure force The Attempt at a Solution I...

In particular how does matter "clump" together to form stars and planets, and how do Galaxy/star systems form? For the latter question is the answer simply that near massive enough bodies, the spacetime curvature is significant enough that the geodesics within its vicinity are closed curves...

Homework Statement Below: Jac = Jacobian matrix; ξ = d/dφ for some continuous parameter φ which labels different points on the worldline. (I'm sorry for my poor English.) Consider a new coordinate system xµ' which differs from the original Cartesian coordinate system xµ; the Cartesian...

If I could route a signal from here-and-now to an event in my past light cone, then clearly I could make an irresolvable causal paradox by having the arriving signal disable the button that sends it, so I'll choose to believe that I can't send messages back in time TO HERE. Now I've heard it...

I have read this paper http://www.sciencedirect.com/science/article/pii/S1355219813000695 that the author try to said that einstein not believe that gravity is not cause the space time curvature. I want to know that this is true or not. Because when I have read about general relativity I always...

haushofer submitted a new PF Insights post General Relativity as a Gauge Theory Continue reading the Original PF Insights Post.

Homework Statement In a certain inertial frame two light pulses are emitted a distance 5 km apart and separated by 5 µs. As observed from another frame, which is traveling parallel to the line joining the points where the pulses are emitted at a velocity v with respect to this frame, the pulses...

Homework Statement [/B] An electron e- and positron e+ annihilate to produce two photons. a_ Why are two photons produced rather than one? b_ Assume that the e- and e+ are at rest just before they annihilate. In their rest frame, what are the energies and momenta of the photons? Define the +x...

Homework Statement [/B] By expanding Krel / Kcl in powers of (v/c)^2, estimate the value of v/c for which Krel differs from Kcl by 10%. Homework Equations Kcl = classical Kinetic Energy = 1/2 m0 v^2 Krel = relative Kinetic Energy = (y-1) (m0 c)^2 The Attempt at a Solution I did a binomial...

Can anyone here settle(or contribute to ) a question that is ongoing at another forum? Who came up with the idea of the rubber sheet analogy in Relativity? Some there have wondered if it was the "rubber sheet geometry" as topology was described as ,apparently that may have ,perhaps...

Dear Physics Forum personnel, Is it possible to learn differential geometry simultaneously while learning the relativity and gravitation? I have been reading Weinberg's book (currently in Chapter 02), but I believe that modern research in relativity is heavily based on the differential...

Source: Basically the video talk about how moving from A to A'(which is basically A) in an anticlockwise manner will give a vector that is different from when the vector is originally in A in curved space. $$[(v_C-v_D)-(v_B-v_A)]$$ will equal zero in flat space...

Homework Statement This is why we build them as colliders now: Some years ago Fermilab used to extract its high energy proton beam for use by "fixed target" experiments situated at the ends of external beamlines a mile north of the Tevatron ring. The energy available for the production of...

Homework Statement <Most of this is irrelevant, the relevant parts are in italics> The Greisen-Zatsepin-Kuzmin (GZK) upper limit on cosmic ray energies The contemporary universe is filled with low energy photons left over from the time when the early universe cooled sufficiently for the...

A Moving Clock runs slow. But, If time t has elapsed in the S frame, does SR apply to a clock moving with speed u in the x-direction in the S frame, relative to the S frame? Or does SR apply only when the clock is in another reference frame S' moving in the x'-prime direction, given that...

...and what is the difference between true 4D and the minkowski space? To me, it would be much easier to see universe as a 4D and us humans just experiencing the dimension of time differently. In my mind i pictured the universe as a complete 4D structure which we humans experience in one...

For those who have read Schutz' book A First Course in General Relativity. Can this book be considered as a deep approach on the subject? Edit --- Do you think I will become a "expert" in general relativity just by reading books like this one I mentioned above? What time it take for learning...

Hello. Consider the following case: Two observers, A and B, moving relative to each other with velocity v. For B, it's A that moves (with v) and so DTb=g*DTa (where DT denotes finite time difference and g is/the Lorentz factor gamma). So, (following the same logic as in Morin's Classical...

If we look Einstein equation ##G_{\mu\nu}=0##, which nontrivial aspects it can gives? One phenomenon is gravitational wave. I suppose that we are also free at initial conditions for this equation, thus we can begin with curved space time? What else?

I have a third circle degree in Physics and I used to be in Theoretical Physics research. Since long, I work in a different field. Therefore, I have no contacts with the international scientific community. I prepared a paper with title “A Heraclitean approach to the Relativity Theories” and...

Homework Statement http://phy240.ahepl.org/Chp1-Relativity-Serway.pdf#page=39 #32 Planet R is 25 lighthours away from Earth. It takes 25 h (according to an Earth observer) for a spacecraft to reach this planet. The clocks are synchronized at the beginning. What is the spacecraft 's time...

Homework Statement A rod of length L0 moves with a speed v along the horizontal direction. The rod makes an angle of θ0 with respect to the x'-axis. (a) Show that the length of the rod as measured by a stationary observer is given by L = L0*√[1-(v2/c2)cos2θ0] (b) Show that the angle that the...

Hello, I wanted to know how Einstein's General Relativity and its equations simplify to Newton's Universal Law. Einstein's equation is obviously a much more generalized version of Newton's law and gives much more accurate predictions that Newton's laws even if we don't think of Newton's gravity...

How is this done in practice? I know that in GR the gravity is believed to curve not only space, but also time, and this prediction has been confirmed somehow in practice. How can we measure that? Because as far as i know, there is no device that actually measures time, but instead measures a...

Homework Statement For a fast moving particle, its momentum and energy are frequently easier to measure than its velocity. a) Show that the factor of beta (as defined by β=v/c), can also be determined by measuring the ratio of relativistic momentum (p) and total energy (E). b) Sketch...

Homework Statement Two events occur in an inertial system K as follows. Event 1: x1 = a, t1 = 2a/c, y1 = 0, z1 = 0 Event 2: x2 = 2.6a, t2 = 1.9a/c, y2 = 0, z2 = 0 What is the velocity of the frame K' in which these events appear to occur at the same time? Express the velocity vector using...

Homework Statement Synchronized clocks A and B are at rest in our frame of reference a distance 2 light minutes apart. Clock C passes A at a speed of c*4/5 bound for B, when both A and C read t =0 in our frame. a) What time does C read when it reaches B? b) How far apart are A and B in C's...

Homework Statement The electric and magnetic fields of a 1 Coulomb charge Q are measured by a pair of field measuring instruments. From the perspective of observers in frame O, the charge is at rest at the origin and one of the field-measuring devices is also at rest, with position (x,y,z) =...

Homework Statement (a) A proton at rest has energy Eproton = mprotonc2 ≈ 938 MeV. (Its momentum is zero). The protons which circulated inside the Fermilab Bevatron had energies close to 1000 GeV (1GeV = 1000 MeV). What value of γ did a Tevatron proton have? (b) Somehow a Bevatron proton...

Hey there, I have two questions - the first is about an approximation of a central gravitational force on a particle (of small mass) based on special relativity, and the second is about the legitimacy of a Lagrangian I'm using to calculate the motion of a particle in the Schwarzschild metric...

Homework Statement The International Space Agency is designing a spaceship to reach the star Proxima Centauri, 4 cyrs (light years) away so that the on-board crew will age 4 years from departure to arrival. How fast must the ship travel? Homework Equations t(moving clock) = t(stationary...

I watched a documentary by Brian Greene, "The Illusion of Time" a few weeks ago, and a question has been bothering me ever since. In the documentary he explains that an alien, traveling toward the earth, would see into our future. So here is my question. The second half of a college football...

Homework Statement A clock moving at v = (3/5)c reads 12:00 as it passes us in our frame of reference, how far away will it be (in light hours) when it reads 1:00. Homework Equations I denote a prime to mean the reference frame of the clock at rest. I use regular lettering to denote 'our'...

Hi, all. My textbook presents an hierarchy of the three types of time, but doesn't back it up or explain where it came from. According to it, Δt ≥ Δs ≥ Δτ Where - Δt is the coordinate time between two events as observed in an inertial frame, - Δs is the spacetime interval between two...

john baez submitted a new PF Insights post Struggles with the Continuum - Conclusion Continue reading the Original PF Insights Post.

john baez submitted a new PF Insights post Struggles with the Continuum - Part 7 Continue reading the Original PF Insights Post.

Homework Statement Unstable particles cannot live very long. Their mean life time t is defined by N(t) = N0e−t/τ , i.e., after a time of t, the number of particles left is N0/e. (For muons, τ=2.2µs.) Due to time dilation and length contraction, unstable particles can still travel far if their...

Hi Everyone! I used to have a book that explained physics concepts quite simply. I used to read it when I was about 8 or 9 years old and one chapter really stuck with me (I'm 25 now). I'm not sure where the book went, and have been looking for it for some time and think this might be the best...

Homework Statement A 35 m long rocket is receding at 0.6c. From the point of view of a stationary observer, how long does it take for light to travel (a) from the bottom of the rocket to the top and (b) from the top to the bottom? Homework Equations t = d/v L = L0 / gamma The Attempt at a...