See also: "Hyperspace Theory & Practice" in the Articles section

ramrobot— A ramscoop starship capable of moving at just under lightspeed, under automated control. Many ramrobots were sent out from Sol system in the 21st through 24th centuries, for exploration and delivery of cargoes to Human colony worlds. Probes designed to seek out potential colony worlds were programmed wrong; they actually located habitable points. As a result, three or four Human colonies were founded by mistake; see slowboat. See also safe ramscoop. ["The Ethics of Madness"]

ramscoop starship, copyright © Adrian Mann 2005

ramscoop— Even in the vacuum of interstellar space, an extremely thin hydrogen gas exists. A conical magnetic field two hundred miles across, projected forward from a traveling starship, scoops up the gas and funnels it into the ship's fusion drive, giving the ship unlimited fuel. Most ramscoop starships can accelerate to near lightspeed, and those built by Pak protectors traveled for tens of thousands of lightyears. The magnetic field of Human-built ramscoops would kill any chordate organism (including all creatures with a backbone) within 300 miles, until the development in 2324 of the safe ramscoop. Humans began using ramscoops on ramrobots in the late 21st century. The hyperdrive made it obsolete circa 2409. [Protector, "The Ethics of Madness"]

reactionless drive— see thruster drive

reactionless thruster— see thruster drive

reading screen— The Slower Than Infinity had one in its habitat bubble in 2645. ["Flatlander"]

The Ringworld, by Todd Hamilton copyright © 1994 by Bill Fawcett & Associates

Ringworld— [Spoiler alert: Ringworld, Ringworld Engineers] An artifact bigger than worlds; a hoop-shaped structure encircling a star 201 light-years from Sol System. The Ringworld's structure, composed of scrith, is a ribbon a million miles wide, with a diameter about equal to Earth's orbit around Sol (Earth's sun); it spins fast enough to provide Earth-like artificial gravity. The Ringworld's inside surface holds an Earth-like habitat inhabited by vastly more sentient beings than all the other worlds of Known Space combined. It is protected by the Solar Laser, and a day/night cycle is provided by a ring of shadow squares in closer orbit around the sun. The protector Proserpina claimed it was been built about a million years ago by an alliance of Pak protectors who disassembled a super-Jovian planet for raw materials; however, this claim is unconfirmed. More recently, until 1733 A.D. much of the Ringworld was controlled by the City Builders, who also colonized several planets in nearby stellar systems. The Ringworld was explored by the First Ringworld Expedition and the Second Ringworld Expedition. [Ringworld, Ringworld Engineers, Ringworld's Children]