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  1. Umaxo

    Research as a hobby

    Hello, I would like to ask you opinions on working in reasearch in physics as hobbiest in my spare time. Right know i am just looking around for options, so any opinion would be appreciated. I have masters degree in theoretical physics. After finishing the study i started working and - long...
  2. Umaxo

    I Limits of the variatonal principle

    Hi, I got curious on the limits of variatonal principle. As far as i know all of the theories can be reformulated as problem of finding extremum of some action. Not only that, but it seems to be most convenient method for looking for new theories in a lot of cases. So my question is, what are...
  3. Umaxo

    Lagrangian mechanics -- Initial questions

    Hi, I am reading Landau-Lifshitz course in theoretical physics 1. volume, mechanics. The mechanics is derived using variatonal principle from the start. At first they start with point particles, that do not interact with each other. Thus the equations of motions must be independent for the...
  4. Umaxo

    Length of a median

    <Moderator's note: Moved from a technical forum and thus no template.> Hi, i am quite embarrassed to ask this question, but i am really stuck. i want to derive length of median of triangle from cosine law and i am getting wrong results. I cannot spot the mistake. So lets have a triange with...
  5. Umaxo

    I Creation of a wormhole

    Hi, if i understood correctly from pop-science literature, there is theoretical possibility of formation of wormholes like in this picture: https://en.wikipedia.org/wiki/File:Wormhole-demo.png bud you need some exotic particles (i think it means negative energy?). Now what i really dont...
  6. Umaxo

    I Geodesic maximality

    Hello, i know that relativists like to extend solutions of einstein equations so that they are geodesicly maximal (i.e. geodesics end only in singularity or infinite value of affine parameter). But why only geodesicly? Thus this geodesic maximality imply, that if i take any timelike or...
  7. Umaxo

    I Principal null directions

    Hi, I know that principal null directions are defined as vector at a point that satisfy the equation ##k_{[a}C_{b]cd[e}k_{f]}k^ck^d=0##, where ##C_{abcd}## is weyl tensor. I know they are used for generating solutions to einstein equations and that they are used for algebraic classification of...
  8. Umaxo

    I Mass/energy in general relativity

    Hi, i got little confused after this conversation in https://www.physicsforums.com/threads/some-questions-about-light-and-relativity.918094/page-2 There was also this conversation: So i want to clear the confusion. As was pointed out to me, in STR mass is defined as m2=E2 - p2, which...
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