SINCE 1966 (ref. 1) there has been observational evidence2–4 that quasi-stellar radio sources (QSRs) and compact radio galaxies are ejected from galaxies. Whatever distance scale one uses, one of the characteristics of QSRs and compact radio galaxies is that a great deal of energy is compressed into very small dimensions. Unless very special conditions prevail, such concentrated sources would be expected to expand with time. Indeed, the short lifetimes which are inferred from their rapid rate of energy expenditure, the associated jets of material and the prevalence of ejected radio pairs across the sources all attest to expansion and eruption.