Hyperspace

During the age of the High Republic Era, a comprehensive understanding of hyperspace eluded nearly everyone within the galaxy. Even through the Imperial Era, it remained enigmatic. Regardless, it constituted a dimension of space-time that existed as an alternative to realspace. Within hyperspace, the conventional principles of space and time were suspended, leading travelers to sometimes employ stasis fields to slow the passage of time on vessels, ensuring the pilot's aging aligned with the rest of the galaxy.

Entry was contingent upon molecular displacement, achieved by surpassing the speed of light. This action generated a simu-tunnel, a pocket within realspace that enabled secure passage through the alternate dimension. The Loth-wolves encountered by the Spectres in 1 BBY possessed a similar capability to traverse at lightspeed through hyperspace tunneling. Hyperspace and realspace were coterminous, indicating that each point in realspace corresponded to a unique point in hyperspace, with adjacent points maintaining their adjacency. Furthermore, every object in realspace—such as stars, planets, and asteroids—possessed a corresponding "shadow" in hyperspace. Beyond these established facts, universally acknowledged by knowledgeable astrophysicists and astrogation experts, many aspects of hyperspace remained shrouded in mystery.

Hyperdrives worked by manipulating hypermatter particles, propelling a starship into hyperspace while preserving its mass/energy signature. This process dramatically reduced travel distances, allowing ships to "jump" from one location to another without traversing the intervening space, thereby significantly shortening journey times. A ship's capacity for hyperspace travel was contingent on its hyperdrive engine; consequently, vessels experiencing hyperdrive failure or lacking one would immediately revert to realspace. Similarly, deactivating a functional hyperdrive would produce the same outcome.

Even seasoned pilots could find rapid hyperspace jumps disorienting, but individuals with sufficient endurance and training could overcome this effect. Some travelers experienced a condition known as Hyperspace whiplash upon exiting hyperspace.

Due to the "mass shadows" cast by large objects in realspace, hyperspace jumps—or "hyperjumps"—required extremely precise calculations. Failure to do so could result in a vessel colliding with a star or other celestial body. To mitigate this risk, designated hyperspace routes were established for interstellar travelers. The discovery of a new, secure hyperspace route could be strategically advantageous in warfare, enabling faster and undetected movement of naval forces. The Galactic Empire deployed Interdictor vessels equipped with gravity well projectors to generate artificial mass shadows, both to force ships out of hyperspace and to prevent them from entering it.

Upon entering hyperspace, a ship appeared to accelerate rapidly—a phenomenon referred to as pseudomotion—and emitted Cronau radiation, which specialized sensors could detect. Hyperspace navigation could be achieved through navigation computers, Force-sensitive navigators, or jump-by-jump methods. The Unknown Regions were characterized by unstable hyperspace pathways, necessitating reliance on navigators and jump-by-jump navigation over navicomputers.

Initiating a hyperspace jump from a stationary position while docked or exiting hyperspace directly into a planet's atmosphere were generally deemed impossible feats, even for highly skilled pilots. Nevertheless, Han Solo accomplished both with the Millennium Falcon during the First Order–Resistance conflict. Indeed, starships were equipped with safety protocols that prevented hyperdrive activation within a planet's gravitational field. While these protocols could be overridden, such actions were exceedingly dangerous, carrying a high risk of ship explosion, severe damage, or disintegration within hyperspace. Successful jumps near planets were possible, however: during the Clone Wars, a cruiser transporting an injured Anakin Skywalker experienced accidental hyperdrive activation within a planet's atmosphere due to droid fighter damage; despite the proximity, the ship successfully jumped to hyperspace without destruction. Jyn Erso and her companions jumped into hyperspace from within the atmosphere of Jedha after the Death Star destroyed the moon's Holy city. While escaping Lothal in a U-wing, Hera Syndulla executed a hyperspace jump directly in front of an Imperial construction module, successfully navigating through the hangar and making the jump. In a desperate attempt to save the remaining Resistance escape ships, Vice Admiral Amilyn Holdo engaged the hyperdrive of the Resistance cruiser Raddus directly into the path of the First Order Mega-class Star Dreadnought, the Supremacy, inflicting substantial damage and effectively obliterating her own ship. This maneuver became known as the Holdo maneuver.

The capacity for hyperspace travel existed naturally. The space-dwelling purrgil species possessed an innate ability to traverse hyperspace. At some point in the distant past of the galaxy, an ancestral species deciphered the secrets of hyperspace travel, thus opening the galaxy to exploration. Legend attributes the initial development of hyperspace travel to the Rakatans, an ancient amphibious humanoid species indigenous to the planet Lehon.

Mastery of hyperspace travel was achieved as early as four millennia prior to the Cold War, evidenced by the existence of hyperspace sextants dating back to that period. In the early stages of the Galactic Republic, hyperspace journeys between the Greater Seswenna and the Core Worlds necessitated astrogation using hyperspace beacons, with frequent reversions to realspace to ensure safe passage. Nevertheless, access to hyperspace travel proved crucial to the Republic's expansion, ushering in an era known as the Great Hyperspace Rush.

Approximately two centuries before the Invasion of Naboo, starships across the galaxy were abruptly forced out of hyperspace during the Great Hyperspace Disaster, orchestrated by the Nihil. Utilizing their path engines, the Nihil executed feats with lightspeed previously considered impossible. Generalirius Nakirre of the Kilji Illumine nation perceived hyperspace as a chaotic realm.

During the First Order–Resistance conflict, the First Order discovered sub-hyperspace, which they employed with their superweapon, Starkiller Base. The firing of Starkiller Base during the Hosnian Cataclysm in 34 ABY unleashed sufficient energy to create a temporary rupture in sub-hyperspace. This event made the disaster instantaneously visible across the galaxy, albeit briefly.