Recent content by dianaj

The geodesics around a spherical mass (Schwarzschild solution) in G.R. can be described by \frac{1}{2}\left(\frac{dr}{d\lambda}\right)^2 + V(r) = \mathcal{E} where V(r) is the effective potential \frac{1}{2}\epsilon - \epsilon\frac{GM}{r} + \frac{L^2}{2r^2} - \frac{GML^2}{r^3} and...

Thank you for your answers - I think my understanding has improved. :)

That's a nice way to think of it. It kind of makes sense. :) Thank you for the link, it looks good. Before I look at it more closely I just have a few questions. The change of coordinates that they calculate, describe how the vector will look, when it has been transported to a new point...

A vector field is parallel transported along a curve if and only if the the corariant derivative of the vector field along the path is 0. That is \frac{d}{d\lambda} V^\mu + \Gamma^\mu_{\sigma \rho} \frac{dx^\sigma}{d\lambda} V^\rho = 0 This is basically what every book says. But what...

No, only in special relativity.

Thanks - just the sort of thing I was looking for! :)

The equation holds in any coordinate system, so it works in Schwarzschild coordinates as well. This is the neat thing about tensors equations and scalars - they don't care much about coordinates. :)

Hey all, I suddenly find myself very confused about velocity and coordinate systems. I have a feeling this is very simple, but sometimes the mind just curls up, you know? ;) When you ask what an observer observe, you need to see things from his point of view - his reference frame. And his...

Hi all, Our sun is approximately a spherical body and accordingly it has a spherical potential. I have just learned that this potential - accoring to general relativity - has a peak and a valley before smoothing out around zero at large distances. One can have an unstable circular orbit at...

You have t' \cdot 1.67 = t and so t' = 1s \Rightarrow t = 1.67 s The time passed describes an event: the 'hand' on the clock moving from on place to another, one second passing. According to the observer this event event takes 1.67 sec's. But according to the moving clock it only...

In a moving system time seems to go slower while objects seem to get longer. As \gamma = \frac{1}{\sqrt{1 - \frac{v^2}{c^2}}} > 1 for v > 0, the correct formula for time dilation must be t' = \frac{t}{\gamma} from which follows t' < t e.g. when t minutes has passed in the rest...

Imagine two spaceships a distance z apart both moving with the same constant acceleration a. The trailing spaceship shoots a beem of light which will be redshifted by an amount \frac{\Delta \lambda}{\lambda_0} = \frac{az}{c} (assuming that \frac{\Delta v}{c} is very small). Due to the...

As most of you probably know, the WEP states that the intertial mass and gravitational mass of any object are equal. This principle has base in Galileo's observations, that all free-falling objects have a constant acceleration. What I would like to get clear is the order of arguments that leads...

It's actually http://www.nbi.dk/~polesen/GRC.pdf" (course starts in september but I can't wait :wink:). If you could recommend a book to read on the side I would be very happy. Ah, I think that's where I went wrong. I think I somehow got it into my head, that the equations only describe...

Hi all, I have just started learning about general relativity. Unfortunately my book is very math-oriented which makes it a bit challenging to understand the content from a physical point of view. I hope you can help. :smile: I am familiar with special relativity theory and Minkowsky Space...