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Hubble constant

  1. Mar 25, 2013 #1
    1. The problem statement, all variables and given/known data
    If [tex]\phi[/tex] is a usual field is it possible that
    [tex]H\dot{\phi}=-\partial^2\phi/{\partial x^2}[/tex]
    Where H is the hubble constant and the dot denotes time derivative

    2. Relevant equations
    [tex]H\dot{\phi}=-\partial^2\phi/{\partial x^2}[/tex]

    3. The attempt at a solution
    I tried different ways but am not able to find the particular expression for hubble constant used here.
    Last edited: Mar 25, 2013
  2. jcsd
  3. Mar 27, 2013 #2


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    On a curved spacetime, the Klein-Gordon equation for a massless scalar field is ##\nabla^\mu \nabla_\mu \phi =0##. If the spacetime is of the FRW type, then there will be a term proportional to ##H\dot{\phi}##. You seem to have missed the ##\ddot{\phi}## term in your expression, so you might want to go through the exercise of working this out from first principles.
  4. Mar 28, 2013 #3
    Thanks a lot. I did miss that term because this was the part i was confused about but i guess that was important too.
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