(d) In a homogeneous and isotropic universe we can represent all distances s by a time-independent comoving distance x multiplied by a time-dependent scale factor a(t), suchthat s = xa(t). Show that this naturally leads to Hubble's law and hence obtain an expres-sion for Hubble's "constant" in terms of a(t) and its derivatives.Explain the limitations of Hubble's law in calculating distances for nearby galaxies withmeasured recession velocities.

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Answered: In a homogeneous and isotropic universe…

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