michel123456 Posted January 3, 2010 Share Posted January 3, 2010 So part of the formula had this factor a(t) multiplying it. Silly question: what is its value? .............. Wait a moment. Are you saying that this a(t) factor can be interpretated as acting upon time? Instead acting upon space? Link to comment Share on other sites More sharing options...

ajb Posted January 3, 2010 Share Posted January 3, 2010 [math]a(t)[/math] is a function of time, it describes the relative expansion of the universe. How it evolves is a dynamic question in GR and can be solved depending on the matter content. In a matter dominated universe we have [math]a(t)\approx t^{2/3}[/math] and for a radiation dominated universe we have [math]a(t) \approx t^{1/2}[/math] (we have assumed a perfect fluid equation of state) For details pick up any book on cosmology, I recommend Andrew Liddle's "Introduction to Modern Cosmology". Link to comment Share on other sites More sharing options...

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