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.
Reference: "The Ethics of Madness", A Gift from Earth
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 80% lightspeed or faster, and those built by Pakprotectors 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 in 2411. See also City Builder ramship.
By 2644, a standard device for reading book tapes. In the common area aboard the starship Argos, reading screens folded out of the walls. In 2645, the starship Slower Than Infinity had one in its habitat bubble. In 2850, Louis Wu had one in his mansion's library on Earth.
A transportation system running around the Ringworld, atop the rim wall. It uses linear accelerators to decelerate cars to merely orbital velocity for travel around the rim, and at the end to accelerate the car back up to the Ringworld’s rotational speed of 770 miles per second. It is accessed by elevators, and elevator shafts are seen as tubes running up the inside of the rim walls. The rings of the linear accelerator are clustered thickly near the elevator shafts, but elsewhere are up to a million miles apart.
Editor's Note: This entry is an overview. For much more information, see Appendix: The Ringworld.
[Spoiler alert: Ringworld, Ringworld Engineers] An artifact bigger than worlds; a hoop-shaped megastructure 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; it rotates fast enough to provide Earth-like spin-induced 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. The floor is sculpted, shaped to resemble a normal world's terrain, with mountains, valleys, seas, rivers, an Earth-like atmosphere, and a living biosphere. The underside of the Ring floor shows the reverse of these shapes, and is protected from meteorite impacts by a layer of foamed scrith. A day/night cycle is provided by a ring of shadow squares in closer orbit around its sun. The Ringworld is protected by the superthermal laser. The protector Proserpina claimed the structure was 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 reportedly colonized several planets in nearby stellar systems. The Ringworld was explored by the First Ringworld Expedition and the Second Ringworld Expedition.
Reference:Ringworld chs. 6-24, The Ringworld Engineers (throughout), The Ringworld Throne (throughout), Ringworld's Children (throughout)
A term meaning those who built the Ringworld. The true identity of the Engineers remains a subject of mystery and controversy. Note that during the First Ringworld Expedition, the civilization called City Builders in later accounts was confused with the true Ringworld Engineers, so the term "Engineers" or "Ringworld Engineers" may refer to either in the account of that expedition (published as Ringworld).
Ringworld native beliefs: During the First Ringworld Expedition in 2851, the Zignamuclickclick natives thought Louis Wu was a Ringworld Engineer because of the advanced technology he displayed. [Spoiler alert: Ringworld]Halrloprillalar Hotrufan (Prill) told the First Ringworld Expedition that her people (called City Builders in later accounts) had built the Ringworld. [Spoiler alert: The Ringworld Engineers] However, in light of the discoveries and revelations of the Second Ringworld Expedition, it appears the City Builders did not build the Ringworld. Most probably this claim was a myth the City Builders told to overawe primitive native cultures. The City Builder civilization almost certainly arose long after the Ringworld was built. [End of Spoiler alert for The Ringworld Engineers. Spoiler alert for Ringworld continues.]
The true Ringworld Engineers: There is little or no real evidence of who built the Ringworld, or why. Speculation follows, some of which is deduction based on the properties of the Ringworld: The Engineers built the Ringworld with a habitat simulating their homeworld, which therefore had the same gravity, atmospheric composition and air pressure, all quite similar to Earth's, and a 30-hour day/night cycle. The Engineers did not have faster-than-light travel, else they would have settled other worlds instead of building the Ring. They apparently had a desperate need for an enormous living space, to have undertaken such an enormous engineering project.
Reference:Ringworld chs. 6, 21; The Ringworld Engineers; Ringworld's Children
(commonly called spacecraft landing ledge) The spaceports on the Ringworld are attached to the outside of the rim walls at the base. There are three apiece on each rim wall, the opposite edges of the Ringworld, spaced equally around the ring. As used by the City Builder ramships, ships approaching the Ringworld were slowed by the spacecraft deceleration rings, then landed in magnetic cradling fields. Ships were launched by being dropped through a trapdoor; the Ringworld spin velocity was sufficient to launch at ramscoop operating speed.
Reference:Ringworld chs. 8, 16
A G2 yellow dwarf star, somewhat cooler than Sol and a touch smaller. The Puppeteers' designation for this star was EC-1752. In late 2850, the time of the First Ringworld Expedition, the Fleet of Worlds had already passed the star, at that time about two and a third light-years away.