$A$ great physicist of this century ($P.A.M.$ Dirac) loved playing with numerical values of fundamental constants of nature. This led him to an interesting observation. Dirac found that from the basic constants of atomic physics ($c, e,$ mass of electron, mass of proton) and the gravitational constant $G$, he could arrive at a number with the dimension of time. Further, it was a very large number, its magnitude being close to the present estimate on the age of the universe ($\approx 15$ billion years). From the table of fundamental constants in this book, try to see if you too can construct this number. If its coincidence with the age of the universe were significant, what would this imply for the constancy of fundamental constants?

(N/A) One relation consisting of fundamental constants that gives the age of the Universe is:
$t = \left(\frac{e^2}{4 \pi \varepsilon_0}\right)^2 \times \frac{1}{m_p m_e^2 c^3 G}$
Where:
$t =$ Age of Universe
$e = 1.6 \times 10^{-19} \; C$
$\frac{1}{4 \pi \varepsilon_0} = 9 \times 10^9 \; N m^2 / C^2$
$m_p = 1.67 \times 10^{-27} \; kg$
$m_e = 9.1 \times 10^{-31} \; kg$
$c = 3 \times 10^8 \; m/s$
$G = 6.67 \times 10^{-11} \; N m^2 kg^{-2}$
Substituting these values:
$t = \frac{(1.6 \times 10^{-19})^4 \times (9 \times 10^9)^2}{(1.67 \times 10^{-27}) \times (9.1 \times 10^{-31})^2 \times (3 \times 10^8)^3 \times (6.67 \times 10^{-11})}$
Calculating this yields a value of approximately $6 \times 10^{17} \; s$, which is roughly $19$ billion years.
If the coincidence with the age of the universe is significant, it would imply that the fundamental constants might not be strictly constant over time, but could vary as the universe evolves.