rubidium-strontium dating: geological dating based on the proportions of radioactive rubidium into its decay product strontium; radioactive rubidium has a half-life of 47,000,000,000 years
investigation: the work of inquiring into something thoroughly and systematically
theory of dissociation: (chemistry) theory that describes aqueous solutions in terms of acids (which dissociate to give hydrogen ions) and bases (which dissociate to give hydroxyl ions); the product of an acid and a base is a salt and water