George Johnstone Stoney (1826 - 1911)
By combinations of Newton's gravitation constant G, the velocity of light c and the electric charge of the electron e, Stoney could construct a mass, a length and a time, using the cgs system of units (1 cm, 1 gram, 1 second):
Using modern values (NIST),
G = 6.674·10-8 cm3 g-1 s-2
c = 2.998·1010 cm s-1
Length L = 1.38·10-34 cm
Time T = 4.60·10-45 s
We can imagine the quantity of mass, but the length and the time are not corresponding to anything of our physical world.
action = energy·time = M·L2 / T =
M·L·c = e2 / c
Planck constant h = 6.626·10-34 Js
cgs System of Units
Using cgs units Coulomb's law is
The unity of charge (1 esu, 1 electrostatic unit) is defined as the charge on each of two bodies separated by 1 cm and attracting each other by a force of 1 dyne (1 dyne = 1 g cm s-2 = 1·10-5 N). Taking q1=q2=q and q2 = F r2 , we get
To convert the electrostac unity (1 esu) to Coulomb (1 C), the the unity of charge of the SI system, we use Coulomb's law
and q2 = 4πε0 F r2
e = 1.602·10-19 C = 4.803·10-10 esu = 4.803·10-10 g1/2 cm3/2 s-1
John D. Barrow: Das 1x1 des Universums. Campus Verlag,
Frankfurt/New York, 2004. John D. Barrow: The Constants of Nature. Jonathan Cape,
John D. Barrow: Das 1x1 des Universums. Campus Verlag, Frankfurt/New York, 2004.
John D. Barrow: The Constants of Nature. Jonathan Cape, 2002.