General relativity Definition and 999 Threads

Hi everyone, I was wondering if I could some advice from anyone who has some experience with higher level general relativity. Any help would be greatly appreciated! Some background: I'm currently working through Robert Wald's General Relativity and am struggling a lot with the "advanced...

Tides on Earth are described with Newton's theory of gravitation. Relativistic effects on tides theoretically become measurable on very strong gravitational fields, possibly becoming twice as strong as tides predicted by Newtonian gravity: http://adsabs.harvard.edu/abs/1983ApJ...264..620N...

Hi, I am in my 3rd year and have General Relativity as one of my options. I'm kind of feeling the peer pressure of selecting General Relativity, but putting all the hype aside, is it really necessary to learn General Relativity for an Experimental Physicist? I have to say, maths isn't really...

Hi everyone, first of all I have been a lurker here for years and have benefited greatly from many of the discussions in the math and physics sections. Thanks, I have received a lot of helpful information from these forums! I have been working through Wald's General Relativity book and I am...

Plain old Newtonian mechanics is time-reversal invariant, i.e. if you view a recording of some events played backwards, it would still appear to be following the same physical laws (gravity attraction law in particular). This type of "time reversal" is exactly equivalent to just turning every...

I'm interested in using a fluid analogy of general relativity to more easily visual what is going on in certain situations, without having to resort to visualizing curved 4d space time which is doesn't come to naturally. However, I don't know relativity quite well enough to understand what...

Hi You guys probably have heard about the monkey and hunter problem. Basically in the monkey an hunter problem you can see the dart hits all the time if you observe the experiment in an accelerated frame of reference ie your falling with the monkey. You see the bullet travel in a straight...

I'm looking for a good text on the foundations of GR. Geared towards physicists, but with a focus on the subtleties of the ideas that went into building the theory rather than on applications. Any recommendations? Thanks!

Homework Statement Essentially, my adviser just told me to get the equation, then expand it so that it doesn't have any tensors. That's it. Just get rid of the tensors. He said that this would be normally found in some textbook...? I've searched a lot of books, but I never saw anything...

Hey guys I was just wondering the following. Since time slows down when traveling faster, and we move around 1.3 million miles per hour, using the CMBR as a frame of reference. Does this mean our perceived lightspeed is wrong? How fast would we measure time to travel if we managed to come to...

Homework Statement Given the metric ds^2=-e^{2\phi}dt^2+\frac{1}{1-\frac{b(r)}{r}}dr^2 find the time component of the 4-acceleration of an object moving with velocity v in the r direction.The Attempt at a Solution The four-velocity of the object is u^a=(t', v) where the prime stands for the...

What aspects of general relativity one could study for a master degree?

Hey all! So, in my study of general relativity, I've come to understand that gravity is actually what physicists would have classically called a "fictitious force", in that it is a force derived from the fact that the observer is not in an inertial reference frame, like in the case of the...

If the Higgs field is responsible for embuing particles with mass, and mass is responsible for gravity, is it possible that the Higgs field will provide the missing link between general relativity and quantum mechanics ie could the Higgs field be the basis of a quantum theory of gravity?

Alcubierre metric: ds^2 = \left( v_s(t)^2 f(r_s(t))^2 -1 \right) \; dt^2 - 2v_s(t)f(r_s(t)) \; dx \; dt + dx^2 + dy^2 + dz^2 What formal conditions are required to verify a valid metric solution of the Einstein field equations? How many possible valid metric solutions are there in General...

We know that the proper time between two events is the shortest possible time between those two events that can be measured in any frame. This follows from the idea that moving clocks run slow-- a stationary clock at rest in S' which moves relative to S at a constant speed v will be time dilated...

Is gravity strong enough to attract 2 galaxies togeather in Gr..I mean is gravity present everywhere in the universe or are there places in universe filled with vacuum and has no gravity waves through it.?

Use the metic that Einstein proposed in the first cosmological model based on general relativity. ds2 = -dt2 + (dr2) / (1 - Kr2) + r2(dθ2 + sin2θd\phi2) where K > 0 Show that the stress energy tensor is that of a static, spatially uniform perfect fluid and determine ρ and p in terms of G and...

Can one detect length contraction due to general relativity? I.e does length/width/height change with distance to a gravitational centre? If so does the object get longer or shorter? I know this is the case with increasing speed in special relativity, but what about GR... If i went into...

I'm not sure if this is the right place to post this topic, but I need some opinions. I would really love to learn General Relativity. I possesses a working knowledge of tensors (namely tensor calculus and analysis). Upon doing some research I was told Gravitation by Misner, Thorne, and...

Suppose we have two bodies of equal mass m and with hyperbolic motion and with small, fixed impact parameter. Now let's assume the speed of the two bodies in the c.o.m frame approaches c. Is there a way - with a delta-function ansatz for the energy-momentum 4-tensor - to understand the...

Is there any research in astrophysics today that does not involve general relativity?

Homework Statement Show that Gij = Gji using the Riemann tensor identity (below) Homework Equations Gij = Rij - 1/2(gijR) Rabcd + Rbcad + Rcabd = 0 R = gmrRmr Rmr = Rmnrn The Attempt at a Solution I have tried to put the Ricci tensor and Ricci scalar (from the Gij...

Why are Quantum mechanics and General relativity incompatible? Probably some complicated mathematics going on? Right?

In relativity, proper time along a world-line is be defined by d\tau^{2} = ds^{2} / c^{2} However, proper time can also be understood as the time lapsed by an observer who carries a clock along the world-line. In special relativity, this can easily be proven: The line element in special...

It had been my understanding that the big bang model of the universe is a theory of the origins of the structure of the universe in which the expansion of the universe is extrapolated back in time until we arrive at a near-singularity and general relativity breaks down. Accordingly, the big...

From the special relativity theory , for explaining the red-shifting of a photon, that has been red-shifted, is the following: point O: origin point of emitted photo, in Galaxy GlxO point R: receiving point of photon, in Galaxy GlxR GlxO, O ---------->----------------R, GlxR Suppose...

Hi there, I am wondering if anyone might be ablet to suggest a good book to give me a working knowledge of general relativity. I have already sat a "relativity and cosmology" undergraduate module but I find that I am still unable to understand papers on gravity. I would like something that is...

Consider the following, from the prospective of General Relativity: A photon's path between two points, point O (emitted point, from galaxy GO) to point R (received point, in Galaxy GR): O: point of photon's origin, in space GFO: gravitational field force at point O, due to its position in...

Hi! I'm reading General Relativity by Wald. In chpater 4.4a about Newtonian limit of linearized gravity, it says: "When gravity is weak, the linear approximation to GR should be valid. The assumptions about the sources (relative motion << c and material stresses << mass-energy density) then...

I see where someone listed a theory that they had https://www.physicsforums.com/showthread.php?t=49230 so going to attempt to do the same. I listed my theory at http://www.bautforum.com/showthread.php/129309-Negative-Mass-Interpretation-of-General-Relativity but they are very quiet and I would...

I am a first year undergraduate who in my spare time is desperately trying to understand what happens when General Relativity and Quantum Mechanics are 'merged'. Almost all of the searches I have done on the subject have turned up with the same similar statements: 'General Relativity and...

I am looking for papers, books or any other resources which I can use to work in General Relativity with Maple. I know, there is GRTensor tool, but it is not up-to-date as far as I understand from its website (latest test was on Maple 11). I use Maple 15. Can you advise me something?

I have very little knowledge in general relativity, though I do have a decent understanding of the theory of special relativity. In special relativity, points in space-time can be represented in Minkowski space (or a hyperbolic space) so that the metric tensor (that is derived in order to...

Homework Statement What is the speed of a particle in the smallest possible circular orbit in the Schwarzschild geometry as measured by a stationary observer at that orbit? Note: The orbit in question happens to be unstable. Homework Equations Normalization condition...

Homework Statement I have a problem. I need to prove that the divergence of Einstein tensor is 0 using the bianchi identities. I have looked to several sources and I have derived an answer, but I don't fully understand some steps. Homework Equations I have uploaded a document which shows a...

Homework Statement I'm staring down a concept homework assignment that is giving me fits. We are just moving into relativity. 6) The quantity γmc^2 represents... a) the rest mass energy. b) relativistic kinetic energy. c) total relativistic energy. d) relativistic momentum. e) None...

for general relativity, all i see on the internet is a bunch of statements clustered together: "oh yeah, general relativity is pretty important and explains black holes, time dilation, and gravitational lensing" but what is it? at a point that has more energy, time goes faster? in other words I...

Homework Statement A spaceship is moving without power in a circular orbit about an object with mass M. The radius of the orbit is R = 7GM/c^2 (1) Find the relation between the rate of change of angular position of the spaceship and the proper time and radius of the orbit. Homework...

Homework Statement I attach a word document with the equations because I don't know how to write them on the post. My question reads: Show that Maxwell's equations Eq (1) is equivalent to Eq (3).Homework Equations The first term of Eq 1 reads: F sub alpha beta comma gamma. That means partial of...

hi I understand that Snell's law describe the relationship between the angles of incidence and refraction, when referring to light passing different isotropic media. someone told me that Snell's law describe also the curvature of space time in General Relativity? is that true? if not what are...

Homework Statement A thought experiment. Imagine ants living on a merry-goround, which is their two-dimensional world. From measurements on small circles they are thoroughly familiar with the number pi. When they measure the circumference of their world, and divide it by the diameter, they...

Exercises of Schutz's "First Course of General Relativity" Dear all, does anybody know where solutions to the exercises can be found? I remember that I found a link in the Web once but I forgot where. Thanks, Goldbeetle

My understanding of the proof goes like this x -star | --- light ray | | O -sun | o -earth The light ray is seen to bend a tiny bit when it reaches earth. My question is this. If we forgot about relativity and assumed the light had a tiny but finite mass (like 10^-100 kg)...

After recently researching about Quantum Field Theory and more specifically gravitons, I am slightly confused with how this theory of the gravitational force fits in with general relativity. I know it hasn't disproved it so there must be some connection. Do gravitons in 11 dimensions cause...

What are the equations from which all of GR can be derived? Obviously one of the equations is Einstein's Field Equation: G^{\alpha\beta}=8\pi T^{\alpha\beta}. I would also guess that you would need the Euler-Lagrange Equations: -\frac{d}{d\sigma}(\frac{\partial L}{\partial...

Hey there, In my university, General Relativity is listed among elective courses (along with an advanced quantum mechanics course). I'm curious to know whether general relativity is really an undergrad course or not. And what are the pros and cons if GR is taken in grad school? Thanks for...

So the principle of equivalence states that any effects due to acceleration must also occur with gravity, as it's impossible to tell the two apart. I get that, but it assumes that gravity exists and you know how much it accelerates objects. But that explanation just predicts what will happen...

I'm a bit confused by the following: We can derive the equation of motion for a particle traveling on a timelike worldline by applying the Euler-Lagrange equations to the Lagrangian \mathcal{L}=- g_{\mu \nu}(x(\tau)) \frac{d x^\mu}{d \tau} \frac{d x^\nu}{d \tau} However, to derive the...