Chemistry — Uranium–Lead Dating

{}^{238}\text{U} \rightarrow {}^{206}\text{Pb}, \quad t_{1/2} = 4.5\ \text{Gyr}

t = \frac{1}{\lambda}\ln\left(1 + \frac{D}{N}\right)

\text{dates the oldest rocks and meteorites}

\text{assumes a closed system}