ABSTRACT
Radioactivity expresses a fundamental complexity and instability of material things. Uranium 238 and thorium 232 seem to be the ‘parents’ of most of the natural radioactivity. The radioactivity of soil derived from rocks gives rise to a flux of nuclear radiation from all land surface which is known to vary from place to place by orders of magnitude. The daily intake of radioactivity by normal people may reach an appreciable fraction of their whole-body burden, but most of this activity is excreted in faeces so that our activity does not increase indefinitely but quickly reaches equilibrium. Nuclear energy may well have been involved in the emergence of life and the suggestion has at least the merit that radioactivity and its accompanying ionization ensures a supply of energy of an effective type at the right place. The energy liberated by radioactivity beneath the surface of Great Britain may be greater than electrical power utilized on the surface.
