1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Electromagnetic in cosmology

  1. May 23, 2009 #1

    trv

    User Avatar

    1. The problem statement, all variables and given/known data

    Title should be: ELectromagnetic signals in cosmology.

    [itex]
    \int\frac{d\rho}{\sqrt{1-k\rho^2}}>=-\int\frac{dt'}{a(t')}
    [/itex]

    The integrals being from r1 to r and t1 to t respectively.

    I can't understand the need for the prime here. Could someone explain to me the significance of the prime?

    2. Relevant equations

    3. The attempt at a solution
     
    Last edited: May 23, 2009
  2. jcsd
  3. May 23, 2009 #2

    nicksauce

    User Avatar
    Science Advisor
    Homework Helper

    It's just because they don't want to have the same variable in the integrand and the bounds of integration. Nothing special.
     
  4. May 23, 2009 #3

    trv

    User Avatar

    Ok so I could just as well write dt, and a(t), i.e. without the prime, as long as I had t1 to t2 or other such in the bounds of the integration?
     
  5. May 23, 2009 #4

    nicksauce

    User Avatar
    Science Advisor
    Homework Helper

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Electromagnetic in cosmology
  1. Cosmology problem (Replies: 3)

  2. Cosmology Problem (Replies: 6)

  3. Cosmological expansion (Replies: 3)

  4. Cosmology Questions (Replies: 5)

Loading...