"All passengers, will you pay attention, please?" All the high-fidelity speakers of the starship Procyon spoke as one, in the skillfully-modulated voice of the trained announcer. "This is the fourth and last cautionary announcement. Any who are not seated will seat themselves at once. Prepare for take-off acceleration of one and one-half gravities; that is, everyone will weigh one-half again as much as his normal Earth weight for about fifteen minutes. We lift in twenty seconds; I will count down the final five seconds... Five... Four... Three... Two... One... Lift!