Using basic constants such as speed of light (c), charge on electron $(e)$, mass of electron $\left(\mathrm{m}_e\right)$, mass of proton $\left(\mathrm{m}_v\right)$ and gravitational constant $(\mathrm{G})$, we can construct the quantity,
$$
\tau=\left(\frac{e^2}{4 \pi \varepsilon_0}\right)^2 \times \frac{1}{m_p m_e^2 c^3 \mathrm{G}}
$$
$$
\begin{aligned}
\text { Now }\left[\frac{e^2}{4 \pi \varepsilon_0}\right] &=\left[\frac{1}{4 \pi \varepsilon_0} \frac{e^2}{r^2} r^2\right]=\left[\mathrm{Fr}^2\right] \\
&=\left[\mathrm{MLT}^{-2} \cdot \mathrm{L}^2\right]=\left[\mathrm{ML}^3 \mathrm{~T}^{-2}\right] \\
\therefore[\tau] &=\frac{\left[\mathrm{ML}^3 \mathrm{~T}^{-2}\right]^2}{[\mathrm{M}][\mathrm{M}]^2\left[\mathrm{LT}^{-1}\right]^3\left[\mathrm{M}^{-1} \mathrm{~L}^3 \mathrm{~T}^{-2}\right]}=[\mathrm{T}]
\end{aligned}
$$
Clearly, the quantity $\tau$ has the dimensions of time.
Put $\mathrm{G}=6.67 \times 10^{-11} \mathrm{Nm}^2 \mathrm{~kg}^{-2}$,
$$
\begin{aligned}
&c=3 \times 10^8 \mathrm{~m} / \mathrm{s} \\
&e=1.6 \times 10^{-19} \mathrm{C}, \mathrm{m}_{\mathrm{e}}=9.1 \times 10^{-31} \mathrm{~kg} \\
&\mathrm{~m}=1.67 \times 10^{-27} \mathrm{~kg} \\
&\text { and } \frac{1}{4 \pi \varepsilon_0}=9 \times 10^9 \mathrm{Nm}^2 \mathrm{C}^2 \\
&\therefore \tau=\frac{\left[9 \times 10^9 \times\left(1.6 \times 10^{-19}\right)^2\right]^2}{1.67 \times 10^{-27} \times\left(9.1 \times 10^{-31}\right)^2 \times\left(3 \times 10^8\right)^3 \times 6.67 \times 10^{-11}}
\end{aligned}
$$
$$
\begin{aligned}
&=2.13 \times 10^{16} \mathrm{~s} \\
&=\frac{2.13 \times 10^{16}}{3.156 \times 10^7} \text { years }=0.667 \times 10^9 \text { years. } \\
&=0.667 \text { billion years. }
\end{aligned}
$$
This time is slightly less than the age of the universe ( $\approx 15$ billion years). It implies that the values of the basic constants of physics should change with time because the age of the universe increases with time.