Introduction

Abstract

The ability of scientists to judge sizes and recognize relationships is crucial to their discipline. It’s an ability which would also serve the general public well in directing its energies most effectively toward such laudable goals as a cleaner and healthier environment. To take a contemporary example, it seems obvious that to gauge the severity of an accidental spill of radioactive material, it would be useful to compare the resultant radiation levels with the unavoidable levels arising from cosmic radiation. Yet how often have we seen the public attention in such cases focused on the total volume of the spill without a mention of the specific radioactivity, as though 100 liters of slightly radioactive water is much worse than 1 liter at a thousand times the concentration of radioactive isotopes? If radioactive levels are specified in news reports, how many persons can judge the significance without a reference to background levels? Understanding the significance of quantitative data is just one of the skills we associate with problem-solving in the physical sciences.