Recent content by purakanui

Cool, thought that would be the case.

I am actually having a little trouble with the anti-symmetric part of your answer. I understand that T_{[ab]} = \frac{1}{2}(T_{ab}-T_{ba}). But how do you expand when the square brackets go over more than one tensor? I.e. in K^aF_{a[v}K_{\sigma]} = 0? Thanks again

Thanks for that!

I am starting my honours project on colliding plane gravitational waves and I am learning about the Petrov-Penrose classification of the Weyl tensor. I can't find any good explanation on what a principal null direction is. Thanks Chris

thanks =)

I have another problem that I am stuck on. Show that a timelike vector cannot be orthogonal to a null vector. Timelike: X^{2} = g(sub a b)X^{a}X^{b} > 0 Null: X^{2} = g(sub a b)X^{a}X^{b} = 0 In order for them to be orthogonal... g(sub a b)X^{a}Y^{a} = 0 I know from the line...

Thanks!

I have also thought about it some more. It is obvious that (del/del y) is a solution because the metric tensor components are either 0 or functions of x. Thus if you use that solution you will get 0 for the lie derivative, making it a Killing vector. But I would like to know how you get there...

Hi. Currently I am self-studying a book on general relativity (Introducing Einstein's Relativity by Ray D'Inverno), I am stuck trying to find a Killing Vector solution to the following problem. ds^2 = (x^2)dx^2 + x(dy)^2 You can easily obtain the metric from the above. Now the question...