Recent content by GrimGuy

  1. GrimGuy

    Lagrangian of system of bodies in PN approximation [Landau Textbook]

    I got your idea, i'll try it. But, do you have other idea to start from 106.16 and arrive in the 106.17, this is my main go. Thanks man.
  2. GrimGuy

    Lagrangian of system of bodies in PN approximation [Landau Textbook]

    Hey guy, I'm having problems to understand the final part of this section. The book says we have the lagrangian from one particle (106.16), then we have some explanation and then the total lagrangian is given(106.17). For me is everything fine until the 106.16, then i couldn't get what is going...
  3. GrimGuy

    A Difficulties with derivative of a vector [Landau Textbook]

    Thx man, I'll take a time to understand and check it. Thank you a lot. EDIT: I checked it and everything is fine and i could undestand the whole explanation, except for one little thing. What u were considering to write it '##n_{a \alpha}##'. It is the modul of the unit vector, or it is just a...
  4. GrimGuy

    A Difficulties with derivative of a vector [Landau Textbook]

    Hi guys, I'm having trouble computing a pass 1 to 106.15. It's in the pictures. So, what a have to do is the derivative of ##f## with respect to time and coordinates. Then I need to rearrange the terms to find the equation 106.15. I am using the following conditions. ##r## vector varies in...
  5. GrimGuy

    A Help with 2nd Order Ricci: Indexes in GR

    Yes, i 'm not sure how to explicit the symmetric property in that solution. Maybe i lack of information.
  6. GrimGuy

    A Help with 2nd Order Ricci: Indexes in GR

    it worked, but it was hard work
  7. GrimGuy

    A Help with 2nd Order Ricci: Indexes in GR

    Nice approach, understood perfectly, except for the symmetry identity. I know it is symmetrical ##h##, but i can't put it in the calculus. How can i explicitly the symmetry property in this solution.
  8. GrimGuy

    A Help with 2nd Order Ricci: Indexes in GR

    Yeah, I'm keeping the ##(h)^2## and neglecting ##(h)^3##.
  9. GrimGuy

    A Help with 2nd Order Ricci: Indexes in GR

    A little transcription mistake, now it's in the correct form.
  10. GrimGuy

    A Help with 2nd Order Ricci: Indexes in GR

    Ohhh, i realize i made a mistake (the first up ##\mu## is actually ##\sigma##), I edit myself to correct it. Yes the ##h## is the small deviation of the flat space.
  11. GrimGuy

    A Help with 2nd Order Ricci: Indexes in GR

    In my studies trying to get the Ricci tensor of 2° order i stuck in this expression: ##h_{\mu}^{\ \sigma},_{\lambda}h_{\sigma}^{\ \lambda},_{\nu}=h_{\mu \lambda},^{\sigma}h_{\sigma}^{\ \lambda},_{\nu}## So, to complete my calculations those quantities should be the same, but i don't understand...
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