Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Clarification on mass-energy tensor and 4-velocity.

  1. Sep 15, 2011 #1

    MathematicalPhysicist

    User Avatar
    Gold Member

    I have next question, we have in the next printcreen the equation:
    [tex]\frac{dU^b}{d\tau}=U^a \nabla_a U^b[/tex]
    why is this right?
    (the printscreen is from the book of Woodhouse in GR, page 34)

    Thanks.
     

    Attached Files:

  2. jcsd
  3. Sep 15, 2011 #2

    MathematicalPhysicist

    User Avatar
    Gold Member

    Ok, I think I can see why this is right, we pick a frame where [tex]U^a=(1,0,0,0)[/tex].

    Clumsy me.
    :-)
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Clarification on mass-energy tensor and 4-velocity.
Loading...