Gr Definition and 937 Threads

If you have the metric g_{ab} , \pi _{ab} as the metric and "generalized momenta", my question is if you can define GR using Poisson Bracet: \dot g_{ab} =[g_{ab},H] \dot \pi _{ab}=[\pi _{ab},H] and hence use these equations to obtain and solve the metric.:shy:

This weekend I played the game of the perihelion precession in GR. I started with the Schwarzschild geometry and used the hamilton-jacobi method. It was quite interresting to compare the integral with the classical counterpart. The full two-body problem may be more complicated to handle...

Can someone help me to calculate the difference between accelerations due to Newton’s law of gravitation and Einstein’s general relativity? Let’s assume the gravitating mass M equals to 1kg and the distance r equals to 1m than the acceleration due to Newton is: a = G * M / r^2 = 6,6742...

In SR, relativitic mass, momentum and energy is conserved but what is conserved in GR since the frames in GR are noninertial.

I've done college courses on both & it's not clear yet how they conflict. I'm looking for a more technical account. Have I done enough to understand it, or do I have to do wait till QFT?

http://www.physorg.com/news12054.html "It demonstrates that a superconductive gyroscope is capable of generating a powerful gravitomagnetic field, and is therefore the gravitational counterpart of the magnetic coil. Depending on further confirmation, this effect could form the basis for a new...

A. Einstein states in The Principle of Relativity, pp 111 - 112: "The modification to which the special theory of relativity has subjected the theory of space and time is indeed far-reaching, but one important point has remained unaffected. For the laws of geometry, even according to the...

Hi I don't know where to start in this question can someone please help me out. Diethylene glycol, although toxic, has occasionally, and illegally, been added to wines to enhance the sweet flavour. Propose an experimental design, including the procedure and the equipment that you would use, to...

I am attempting to learn GR (for fun) using Sean Carroll's text. I have made it ALL the way to . . . . page 9 I don't understand the equation on the bottom of page 9; (1.16) (namely, why there are TWO delta x ^u and delta x^y; but to type out my question I will need to know how you guys...

In words, how would a path of an object moving in a straight line with a constant velocity differ from the path of an accelerating object moving in a straight line according to Einstein's picture of curved space-time?

Is it possible to define linear momentum in any curved space? According to wikipedia, it's not: http://en.wikipedia.org/wiki/Linear_momentum Why? Which is an example of space-time asymptotically Minkowski?

Published in ScienceExpress this week (the full citation when it appears in Science will be in our Noteworthy Physics Papers thread in the General Physics forum): M. Kramer et al. Tests of General Relativity from Timing the Double Pulsar, ScienceExpress 14 Sept. 2006 Abstract: The double...

http://arxiv.org/abs/astro-ph/0609417 Tests of general relativity from timing the double pulsar M. Kramer, I.H. Stairs, R.N. Manchester, M.A. McLaughlin, A.G. Lyne, R.D. Ferdman, M. Burgay, D.R. Lorimer, A. Possenti, N. D'Amico, J.M. Sarkissian, G.B. Hobbs, J.E. Reynolds, P.C.C. Freire, F...

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...

Which came first Quantum Mechanics or General Relativity? Or to rephase it another way, Which came first Hawking radiation or the Big Bang. Why did the singularity or black hole, which we assume caused the big bang, not simply evaporate instead of exploding, as currently accepted...

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...

Some say that the reason Einstein developed the GR is because he wanted to avoid the spooky "action at a distance," since two massive bodies exerting forces on each other at a large distance with no "mediator" seems rather odd. Therefore Einstein invented the concept of spacetime and gravity...

Hi guys, I am trying to study GR on my own. You got any good books in mind?

Hi I have a great inerest in SR and GR.As I am in quite learning stage I have started reading docs regarding this from internet. Presently I am reading a book 'Introduction to special relativity' by Robert Resnik. Is there any FREE book available on net on this subject or tell me the way I...

Hello could someone give some info about the "Numerical solution" to GR...is this a field of "Computational Physics"?.. - What i know is that you take the Hyper-surface, and you " split " it into triangles..and use the ¿angles? of every triangle as finite-coordinates..then you get a problem...

Local coordinate system in GR observed. If one considers coordinate systems in General Relativity. I think, if I understand it well enough, that in GR space & time and or in space-time a coordinate system depends on locality, e.g. on an average distance between galaxies an the total amount...

In GR, can a spinning object be traveling on a geodesic?

Is it justified to state that GR is "just" a geometrical theory to calculate the paths of objects in spacetime? Just because GR states that "gravity is a property of spacetime itself" doesn't necessary mean that spacetime is curved; just that the paths of objects in spacetime are curved in a...

May as well announce my Java applet that simulates Newton's law of gravitation. The initial conditions are set to give a demonstration of conservation of angular momentum. That is, 8 test masses are launched, all with the same angular momentum, and their orbits cross on the other side of the...

The Reader is invited to help this thread become rigorous. If any links should not fubction, inform me, I will try to correct them. Currently this thread is an analogous interpretation of circumstantial evidence and incomplete information. The writer has attempted to crudely use the...

REF: Smolin; Perimeter Institute; -- “The case for background independence” What does background independence mean. Are statistical probabilities needed to compare separated events. If the background that physics works on varies relative to distant locations in GR does that mean GR is...

Hi All, I was hoping someone could help point me in the right direction. I'm interested in simulations of General Relativity with generic mass distributions that are self gravitating, i.e. that the metric of the space-time being considered is dynamically altered by the distribution of mass whose...

Are superstrings (and related M-theory) the only option for a theory of everything? Wikipedia states: "The only mainstream candidate for a theory of everything at the moment is superstring theory / M-theory; current research on loop quantum gravity may eventually play a fundamental role in a...

I hope someone else finds this interesting, since it through me for a loop for a while. Ok, so time dilation occures in gravitational fields. I used the solution for the time coordinate transformation between "free" space and the space under gravitational influence: t_g =...

:confused: Some papers say that Palatini Formalism still works if the frame variables e^i_a is not an isomorphism (from tangent bundle to frame bundle), this generalizes GR to include the cases of degenerate metric. But one could not derive the Einstein's Equation if e^i_a is not an...

http://www.physorg.com/news12054.html "It demonstrates that a superconductive gyroscope is capable of generating a powerful gravitomagnetic field, and is therefore the gravitational counterpart of the magnetic coil. Depending on further confirmation, this effect could form the basis for a new...

Over in https://www.physicsforums.com/showthread.php?t=115295 on the forum they are talking about this research being hailed as a test for GR...BUT...could someone tell me if the "gravitomagnetic" field in http://www.physorg.com/news12054.html was what Heim was talking about. I think it's...

http://www.physorg.com/news12054.html Scientists funded by the European Space Agency have measured the gravitational equivalent of a magnetic field for the first time in a laboratory. Under certain special conditions the effect is much larger than expected from general relativity and could...

I like simple physical setups to articulate and generate good thought experiments. Setup: Consider a hole cut in a flat sheet of material with these conditiond; Bottom portion is perfectly circular with 150 degrees of arc. End points are represented by x=+n, y=0 and x=-n, y=0. x=0, y=0...

Here is a thought experiment that doesn't seem to add up. Suppose you have a unit of mass at rest on the surface of Earth that spontaneously transforms to photos all moving radially outward into space. At some distance (say 1Km) the photons revert back to the original mass but are now 1Km...

The other day, I was trying to explain what SR & GR were for some non-science friends of mine. I started speaking of motion with constant speed, the postulates of SR, the spaceship and the ball, time dilatition, twin paradox and so on. Needless to say, they didn't understand what I was talking...

I hope that some of the folks (Mike, Howard, Patrick, Robin) who have engaged in the other threads [1][2][3] on outcome counting (ie Patrick's APP) see this thread. Starting with the Feynman path integral formulation of ordinary quantum mechanics, it is pretty straightforward to derive...

im stuck on the last question of this lab. "what combination or masses would make the accelration of an atwood machine equal to 1/2 g?" a = g (m1 - m2/m1=m2) so i have to find out what m1 and m2 are eual to in that forumula if g = 1/2 im thinking a is equal to 9.81 because the...

hey again, still looking for projectile motion + circular motion problems (only in horizontal plane). Can anyone please help me make up a question with these two concepts in one. If possible make it a 5 STAR complex question! I am also studying charged particles in a electric field which...

Hello all, Can the method of analytic continuation [1] be applied to the calculation of the metric over a 4-d manifold? In other words, suppose that we are given the value of the metric g_ab as well as its power series at a single point p in a 4-dimensional manifold. Assume further that...

The perihilion of Mercury and the eclipse of 1919 (Eddington expedition) are given as the first experimental verifications of General relativity. However, feeling pedantic, I was curious just which one these is accepted as the vital first prediction of GR in agreement with the real world? If...

I've read in multiple locations that GR is necessary to properly explain a co-rotating perspective/observer of the experiment. Additionally, SR can explain the experience of non-inertial observer. The above two statements seem somewhat conflicting and leads to my question. Why is it that...

In black hole physics and GR, what does the term back reaction means?

When a canon shoots a ball straight up (one dimension), the ball only accelerates as long as the nongravitational force of the canon acts on it. After that, the ball decelerates in the gravity field until the point it turns back and accelerates in the opposite direction as it falls back on...

Does time-like curvature of spacetime cause light to bend, for example, around the sun? Or is the gravitational bending of light only due to the space-like curvature? So far, I understand the concepts as: Time-like curvature is caused by the mc^2 part of E, while space-like curvature is caused...

I am curious as to just when time dilation plays a part as an effect of GR. I am told that clocks tick slower in a gravitational field. Is this an accurate portrayal, or would it be more accurate to say that time ticks slower in all accelerating reference frames? That is, does GR time dilation...

In the past I've spoken about mass a kagillion times. There was one aspect that I had to hold off on until I taught myself the details and meaning to a good level of understanding. I've now come to that level and have made another web page to describe it. The aspect I'm speaking of is "active...

Hey folks, working problems in Hartle's GR book and having trouble with this one. Chapter 9 discusses the simplest physically relavent curved geometry, that of Mr. Swarzschild ds^s = -(1 - \frac{2 G M}{r}) dt^2 + (1 - \frac{2 M}{r})^{-1} dr^2 +r^2(d\theta^2 + sin^2\theta d\phi^2) In this...

Help Exam Tmr! 112 Physics *FORCES* As you may have guessed from the title, I'm in a bit of a bind here. You see the website with the answers to the review questions I'm working on isn't working... and there's an exam tomorrow. Here's a few of the questions any help would be greatly...

This is an analysis involving general relativity (GR). Let a spherically symmetric, uncharged, nonrotating star (not a black hole—that comes later) have an escape velocity = infinitesimally less than c at its surface. Then its r-coordinate radius (also known as the reduced circumference and...