Hubble's law: If the Hubble constant is 25 km/s per million light-years, use it to estimate the age of the universe? (c = 3.00 × 10⁸ m/s, 1 ly = 9.461 × 10¹⁵ m, 1 y = 3.156 × 10⁷ s) A) 10 Gy B) 12 Gy C) 15 Gy D) 20 Gy E) 25 Gy

Question

Quizplus · Accepted Answer

The age of the universe can be estimated as the inverse of the Hubble constant. First, convert the Hubble constant to SI units: $25 \, \text{km/s per million light-years}$ = $25 \, \text{km/s per} \, 9.461 \times 10^{15} \, \text{m}$. This gives $2.64 \times 10^{-18} \, \text{s}^{-1}$. The age of the universe in seconds is the inverse of this, $3.79 \times 10^{17} \, \text{s}$, which converts to approximately 12 billion years (12 Gy) when divided by the number of seconds in a year ($3.156 \times 10^7 \, \text{s/year}$).

Hubble's Law: If the Hubble Constant Is 25 Km/s Per