--- title: Stardrive summary: The invented faster-than-light drive that carries a Pax Abyssi ship between stars. The pilot locks a star, charges the drive, turns onto the target and flies the ship to the speed of light by hand; at 1.0c the jump begins. science_status: [fiction, sim] categories: [Ship systems, Ships and technology, Interstellar travel, Fiction] aliases: [FTL drive, Faster-than-light drive, Jump drive, Lightspeed jump, FTL LOCK, Stellar lock, Hyperspace] infobox: type: technology name: Stardrive function: "Interstellar travel between star systems" science_status: "FICTION: no known physics allows a ship to reach or exceed the speed of light" sequence: "lock a star; arm and charge; align the nose on the star; fly to 1.0c by hand; the jump; the tunnel; drop out at the destination" lock_acquisition_s: "3 to 10 (random)" charge_s: 3 alignment_gate_deg: 10 thrust_during_run: "forward thrust multiplied by 20 while the drive is engaged" run_to_c_from_rest_s: "about 15 of held throttle" cues: "rumble at 0.8c; boom, flash and streaks at 1.0c" designed_ftl_speeds: "1.1c on entry to 5,000c, speed doubling every 10 s above 2c at full throttle (designed, not yet built)" fuel_in_fiction: "antimatter, burned in proportion to the square of speed (designed, not yet built)" build_status_2026_09: "lock, checks, charge, alignment, hand-flown run to c, jump, tunnel and arrival: BUILT; FTL throttle, antimatter bill, dropping out between stars: designed, not built" sim: entity: ship_system.stardrive refs: - id: einstein1905 type: article-journal author: [{family: Einstein, given: Albert}] title: "Zur Elektrodynamik bewegter Körper" container-title: Annalen der Physik issued: 1905 volume: 322 page: "891-921" DOI: 10.1002/andp.19053221004 - id: alcubierre1994 type: article-journal author: [{family: Alcubierre, given: Miguel}] title: "The warp drive: hyper-fast travel within general relativity" container-title: Classical and Quantum Gravity issued: 1994 volume: 11 page: "L73-L77" DOI: 10.1088/0264-9381/11/5/001 - id: pfenning1997 type: article-journal author: [{family: Pfenning, given: Michael J.}, {family: Ford, given: L. H.}] title: "The unphysical nature of 'warp drive'" container-title: Classical and Quantum Gravity issued: 1997 volume: 14 page: "1743-1751" DOI: 10.1088/0264-9381/14/7/011 - id: lubin2016 type: article-journal author: [{family: Lubin, given: Philip}] title: "A Roadmap to Interstellar Flight" container-title: Journal of the British Interplanetary Society issued: 2016 volume: 69 page: "40-72" URL: https://arxiv.org/abs/1604.01356 - id: nasa_voyager1 type: webpage author: [{literal: "NASA"}] title: "Voyager 1" container-title: NASA Science URL: https://science.nasa.gov/mission/voyager/voyager-1/ accessed: 2026-09-27 images_wanted: - file: File:Stardrive_jump_tunnel.avif subject: "Cockpit view at the moment of the jump: the flash and star streaks as the ship crosses 1.0c, then the tunnel seen through the forward and side windows" source: sim note: "shot list: no approved capture exists; the tunnel's look is being rebuilt, so shoot after the new look lands" - file: File:Stardrive_window_align.avif subject: "The on-screen stardrive window during the run to c: the ALIGN readout green inside the 10 degree gate, the speed readout in fractions of c, the ENGAGE and DUMP CHARGE buttons" source: sim note: "shot list" - file: File:Relativistic_aberration_diagram.svg subject: "Diagram: the same star field seen at rest and at 0.9c, with the stars crowded toward the direction of travel and the forward ones shifted blue, the rear ones red; labelled as the effect the game does not draw" source: other note: "shot list: diagram, CC BY-SA by Pax Abyssi" --- :::callout{type=warning title="Fiction"} The stardrive is invented. No known physics lets a ship reach the speed of light, let alone pass it. This page describes how the drive works in the game and then what real physics says about each step. ::: The **stardrive** is the ship system that carries a Pax Abyssi ship from one star system to another. The pilot locks a destination star, charges the drive, turns the ship onto the star and then flies it up to the speed of light by hand, with the drive multiplying the ship's forward thrust. When the ship reaches 1.0c, the speed of light, the jump fires, the ship enters the tunnel, and it emerges in the destination system. The design goal is that the pilot makes the crossing, with a moment of achievement when the speed readout touches 1.0c. ## Flying the stardrive **Lock.** Select a star, on the galaxy map or in the sky, and press FTL LOCK. The lock takes a random three to ten seconds to acquire. It refuses the star system the ship is already in. **Arm and charge.** Pressing the drive runs its checks in order (a target, a lock, fuel, power, a working drive) and names the first one that fails. If all pass, the drive hums and charges for about three seconds. DUMP CHARGE throws the charge away and returns the drive to ready. **Align.** The pilot turns the ship until its nose is within 10 degrees of the locked star. The drive will not engage outside that cone. **The run to light speed.** On ENGAGE the dampers come off and the drive multiplies the ship's forward thrust twenty-fold. From rest, about fifteen seconds of held throttle brings the ship to the speed of light. A low rumble starts at 0.8c. Engaging the dampers or pressing ABORT RUN stops the run. **The jump.** At 1.0c, with the nose still on the star, the jump fires: a boom, a white flash, stars stretching into streaks, and the tunnel. If the nose has drifted off the star, the jump waits until the pilot brings it back inside the cone. **Arrival.** Dropping out plays the drive's power-down and the ship emerges in the destination system. ::figure{src="File:Stardrive_jump_tunnel.avif" size=wide alt="Cockpit view as the ship crosses the speed of light: a white flash and stars stretched into streaks around the forward windows." caption="Sim render: the jump at 1.0c, seen from the cockpit."} ## The numbers, put in perspective The run to light speed is where the game's numbers meet real physics most directly, so it is worth working them through. **Acceleration.** Reaching 300,000 kilometres per second in about fifteen seconds means accelerating at roughly 20,000 km/s every second, about two million times Earth's surface gravity. No crew and no structure could survive that for a fraction of a second. The game accepts it as part of the fiction, alongside the drive itself. **Energy.** Special relativity sets the energy needed to reach a speed $v$. A body of mass $m$ carries kinetic energy $$ E_\mathrm{k} = (\gamma - 1)\,mc^2, \qquad \gamma = \frac{1}{\sqrt{1 - v^2/c^2}}, $$ where $c$ is the speed of light and $\gamma$, the Lorentz factor, grows without limit as $v$ approaches $c$ :cite[einstein1905]. For a 100-tonne ship at half the speed of light, $\gamma = 1.155$ and the kinetic energy is about $1.4 \times 10^{21}$ joules. That equals the rest-mass energy of about 15.5 tonnes of matter: the complete annihilation of nearly eight tonnes of antimatter with eight tonnes of ordinary matter, with every joule going into motion. At 0.99c, $\gamma = 7.1$ and the bill rises about fortyfold. At exactly $c$ it is infinite. This is why nothing with mass can reach the speed of light, and why the game's jump at 1.0c is fiction from the first step. **Antimatter.** In the game's design, the drive pays for its speed in antimatter, and it is the right fuel to imagine: when a gram of antimatter meets a gram of ordinary matter, all two grams become energy, $E = mc^2 = 1.8 \times 10^{14}$ joules, about the yield of a 43-kilotonne explosion. Nothing else stores energy so densely. The catch in reality is supply. Particle accelerators make antimatter an atom at a time, in quantities far too small to weigh. **Time and light.** A real ship near light speed would see its own clocks run slow compared with the stars' (at 0.8c, $\gamma = 1.67$, so the crew would age 60% as fast as the people they left). It would also see the sky distort. Starlight arriving from ahead would crowd towards the direction of travel and shift towards the blue, and the view behind would thin and redden. The game draws none of this: during the run the sky looks as it does at rest. ::figure{src="File:Relativistic_aberration_diagram.svg" size=wide alt="Two views of the same star field, one at rest and one at 0.9 times the speed of light, with the stars bunched towards the centre and coloured blue ahead." caption="Diagram: what a real ship would see near light speed. At 0.9c the stars crowd towards the direction of travel and shift blue ahead; the game does not draw this effect."} **The boom.** Sound needs a medium to travel through, and interplanetary space is close to empty, so there is nothing to carry a boom and nothing to break at 1.0c. A sonic boom happens when an aircraft outruns its own pressure waves in air. The nearest real analogue for light is **Cherenkov radiation**, the blue glow in a reactor pool, emitted when a charged particle moves through water faster than light travels in water. It cannot happen in a vacuum, where nothing outruns light. The boom is a sound designed to mark the moment. ## Why the gaps are so wide The fiction needs a faster-than-light drive because real distances between stars are enormous. The nearest star, Proxima Centauri, is 4.24 light years away. Voyager 1, humanity's farthest spacecraft, is leaving the Solar System at about 17 kilometres per second :cite[nasa_voyager1]; at that speed Proxima would be about 75,000 years away. Even the stardrive's designed top speed of 5,000 times the speed of light would leave the Galaxy large. Proxima would be about 7.4 hours away, the region of human settlement in the game's setting, roughly 800 light years across, about two months, and the [[Milky Way]]'s disc, about 100,000 light years across, some twenty years. ## Real ideas for fast interstellar travel Physics offers two kinds of answer, neither of them a stardrive. The first stays below light speed and makes the ship small. Directed-energy proposals would push wafer-scale probes of a few grams on light sails with powerful ground-based lasers, to more than a quarter of the speed of light, reaching the nearest star in about twenty years :cite[lubin2016]. Nothing with people aboard fits that plan. The second bends spacetime instead of moving through it quickly. In 1994 Miguel Alcubierre found a solution of Einstein's equations of general relativity in which a region of space contracts ahead of a ship and expands behind it, carrying the ship along at any speed while it never locally outruns light :cite[alcubierre1994]. The catch is that the geometry requires regions of negative energy density, which no known form of matter provides in bulk. Applying the quantum limits on negative energy, Pfenning and Ford showed that the total energy needed to hold such a bubble together is physically unattainable :cite[pfenning1997]. Warp metrics remain a useful way to study what general relativity allows; they are not an engineering design. Faster-than-light travel carries a further problem that no drive design escapes. In relativity, observers moving relative to each other disagree about which distant events happen at the same time :cite[einstein1905]. A signal or ship that could outrun light could, for some observers, arrive before it left, and such travel could be used to send messages into one's own past. Most physicists read that as a strong sign that nothing travels faster than light. :::callout{type=sim title="In Pax Abyssi"} Built and flyable as of September 2026: locking a star from the sky or the galaxy map, the drive's checks and charge, the 10 degree alignment gate, the hand-flown run to light speed at twenty times normal thrust, the jump at 1.0c, the tunnel ride and arrival in the target system. Every step has an on-screen control and its own cancel, and the drive can also be armed from the overhead panel. The tunnel is a presentation: the ship does not cross the space between the stars, and the destination system loads when it drops out. The sky is the view from Sol everywhere in the current build, so arriving at another star does not yet change the constellations. Designed in the original simulation and not yet built in the game: a faster-than-light throttle from 1.1c to 5,000c, with speed doubling every ten seconds at full throttle; an antimatter bill that grows with the square of speed; and dropping out of the tunnel between stars, stranded in deep space, if the pilot slows below 1.0c or the antimatter runs out. None of the relativistic effects described above is modelled at any speed. ::: ## See also - [[Milky Way]] - [[Star catalogue]], the real stars you can lock - [[Sol]] - [[Orbit]] - [[Science in Pax Abyssi]], on how the wiki labels fiction