The Hubble law (28-9)

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Question

Hubble constant = 70 km/s/Mpc = \(2.3 \times 10^{−18}\mathrm{s}^{-1}\)
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Review

This direct proportionality is called the Hubble law, and the constant \(H_0\) in Equation 28-9 is called the Hubble constant. Astronomers typically measure distances in the cosmos in parsecs (pc), a unit equal to 3.26 light-years. One light-year (ly) is the distance that light travels in one year, equal to \(3.09 \times 10^{16} \mathrm{m}\). The current best value of \(H_0\) is about 70 km \(/\ \mathrm{s}\ /\ \)Mpc, where 1 Mpc = 1 megaparsec = \(10^6\ \mathrm{pc} = 3.26 \times 10^6\) ly.