Mundane Realities

Primel units are derived from certain "mundane realities" of human life. This means certain physical phenomena which human beings observe or experience within their environment, including:

• the mean solar day
• the acceleration due to Earth's gravity
• the maximal density of water
• the massic heatability (specific heat capacity) of water
• the electrical impedance of free space
• the atomic mass of carbon-10_z (carbon-12_d)
• the luminous efficiency function of the human eye