LOR-1: Nothing accelerates to c

Every L1 scheme that proposes to push harder.

Kind: constraint · Family: LOR (Kinematics) · Last reviewed: 2026-09-12

The result

A massive body cannot be accelerated to c: its kinetic energy grows without bound as v approaches c, so velocities greater than light have no possibility of existence for anything that starts below it

What it forbids or costs

Every L1 scheme that proposes to push harder

Escape hatches

Never having been below c (tachyons, LOR-2); changing the geometry instead of the velocity (L2, L3)

Who it bites

Physics proposals

• DODGES: Heim theory and the Dröscher-Häuser propulsion proposal (2004 to 2005). The craft accelerates in ordinary space at 1g and the papers explicitly rule out $c' > c$ in $\mathbb R^4$; the superluminal displacement is assigned to a space with $c(n) = nc$, which is the leave-the-manifold move and is outside what Einstein's argument covers.
• DODGES: Lorentz-violating frameworks (the Standard-Model Extension and Hořava-Lifshitz gravity). Each species has its own maximal attainable velocity $c_a$ and its energy diverges as $v \to c_a$, not as $v \to c$; a body with $c_a > c$ passes $c$ with finite energy, which Einstein's argument does not cover because it assumes one invariant speed.
• DODGES: Meta relativity (Bilaniuk, Deshpande and Sudarshan 1962). Einstein's argument bounds a body that starts below c; the paper's class III particles are "created at super-luminary velocities" and never cross the barrier, which is the escape hatch the register itself names.
• DODGES: Tachyons (Feinberg 1967). The register lists never having been below c as the escape hatch from Einstein's 1905 argument, and Feinberg's pair-production picture takes exactly that hatch: nothing is accelerated through c.
• DODGES: The OPERA superluminal neutrino (2011). The neutrino is massive and starts below c, so the claim could not be a body accelerated through c; the responses read it as a maximal attainable velocity above c (Coleman and Glashow kinematics), which is outside the Lorentz-invariant argument LOR-1 states.
• SATISFIES: Alcubierre 1994: the warp drive metric. Nothing is accelerated to $c$; the ship is on a timelike geodesic with $d\tau = dt$ and zero proper acceleration, and the loophole is that the geometry moves, not the ship.
• SATISFIES: Bobrick and Martire 2021: physical warp drives. States that "there is no known way of accelerating regular material beyond the speed of light" and that a superluminal shell can only be postulated, like a superluminal test particle
• SATISFIES: Brane-bulk shortcuts (Chung and Freese 2000, Ishihara 2001, Caldwell and Langlois 2001). Nothing is accelerated to $c$; the graviton is massless and the bulk geodesic is null.
• SATISFIES: Einstein–Rosen bridge (1935). Nothing is accelerated to or past $c$; all motion is timelike or null within the manifold.
• SATISFIES: Entanglement signalling and the no-communication theorem. No massive body is pushed towards c; the particles travel to their stations at ordinary speeds
• SATISFIES: ER = EPR (Maldacena and Susskind 2013). Nothing is accelerated to $c$; Alice and Bob move on timelike world lines and meet, if at all, inside the horizons.
• SATISFIES: Everett and Roman 1997: the superluminal subway. Inside the tube the ship propagates causally with $|dx'/dt'| < 1$ in the local Minkowski frame; the superluminality is a property of the opened cone as seen from outside.
• SATISFIES: Fell and Heisenberg 2021: positive energy from hidden geometric structure. Motion is geometric; the central observer is inertial and nothing is pushed through $c$
• SATISFIES: Fuchs et al. 2024: the constant-velocity physical warp shell. $\beta = 0.02$; the Lorentz transformation used to build the comoving shift exists only below $c$, and subluminal speed is one of the paper's three stated ingredients
• SATISFIES: Gao, Jafferis and Wall: traversable wormholes via a double-trace deformation (2017). Nothing is accelerated to $c$; the traversing signal is a light ray or a quantum that follows a null geodesic of the perturbed geometry.
• SATISFIES: Gott's cosmic-string time machine (1991). Each string moves at $v < c$ and no body is pushed to light speed; the observer's loop is timelike throughout.
• SATISFIES: Kaluza-Klein and the hyperspace reading (Kaluza 1921, Klein 1926, ADD 1998, Randall-Sundrum 1999). Motion in the compact dimension is not a velocity but a mass: a particle with momentum $n/R$ around Klein's circle is a four-dimensional particle of mass $n/R$ obeying ordinary kinematics, and nothing is accelerated to $c$.
• SATISFIES: Krasnikov 1998: the tube laid on the way out. The ship is always inside its local light cone; the return is superluminal only relative to the outside frame because the cone has been opened, not because the ship has been pushed.
• SATISFIES: Lentz 2021: hyper-fast positive-energy solitons. Nothing is pushed through $c$; the Eulerian observers in the central region are in free fall with $d\tau = dt$ and the motion is geometric
• SATISFIES: Maldacena, Milekhin and Popov: traversable wormholes in four dimensions (2018), and the humanly traversable sequel (2021). The traveller free-falls; the boost to $\gamma \sim 10^{12}$ at the centre is gravitational and the world line stays timelike.
• SATISFIES: Morris, Thorne and Yurtsever: the wormhole time machine (1988). The mouth is moved at $v < c$ and the traveller moves at $v < c$ everywhere; the effect is purely a clock offset.
• SATISFIES: Morris–Thorne traversable wormhole (1988). The traveller moves at $v \ll c$ throughout; nothing is pushed to light speed.
• SATISFIES: NASA Eagleworks warp field interferometer. The documents insist the craft "never locally breaks the speed of light"; the mechanism claimed is geometric
• SATISFIES: Natário 2002: warp drive with zero expansion. The Eulerian observers, including the ship, are in free fall inside their light cones; the exterior flows past. Nothing is pushed to $c$.
• SATISFIES: Passage through the Kerr interior (Carter 1968). The traveller free-falls on a timelike geodesic at $v < c$ throughout.
• SATISFIES: The EM drive. Even a working reactionless thruster would approach c asymptotically; its supposed advantage is unlimited delta-v, not a route past the limit
• SATISFIES: The Mach effect thruster. A working Mach effect thruster would still be a rocket without exhaust, approaching c from below with kinetic energy growing without bound; its advantage would be delta-v, not speed
• SATISFIES: The relativistic rocket. This is the constraint the rocket lives inside. Its speed approaches c asymptotically and the kinetic energy grows without bound, which is why the mass ratio is exponential in the crew time and the bill is B-mass
• SATISFIES: Van Den Broeck 1999: the pocket geometry. The pocket centre moves on a timelike geodesic with proper time $t$; nothing is accelerated to $c$.
• SATISFIES: Visser's thin-shell wormholes (1989). The traveller crosses a flat face at any subluminal speed with no acceleration.
• SATISFIES: Warp drives in modified gravity. The ship is on a timelike geodesic of the unchanged metric, and in Einstein-Cartan theory the torsion, localised in matter, does not affect it.
• SATISFIES: Wheeler's geons and quantum foam (1955–1962). Nothing massive is pushed to $c$; the geon's contents are light, moving at $c$, held by gravity.
• SATISFIES: White et al. 2021: the worldline-numerics Casimir pattern. Nothing is pushed toward $c$; the mechanism invoked is geometric

Fictional drives

• SILENT: Alien's Nostromo. The ship exceeds c by the film's own numbers and the film never says how; the light barrier applies and is not mentioned
• SILENT: Babylon 5: hyperspace, jump gates and beacons (1993 to 1998). Ships never approach light speed in normal space and the show never says why the gain must come from distance rather than speed.
• SILENT: Banks's Culture: the energy grid, infraspace and ultraspace (1987 onward). Sublight travel in the Culture is rare and the light barrier is never stated as the reason for the grid.
• SILENT: Dune: the Guild navigators and folding space (Herbert 1965). The novel never says the ship moves fast or slow; the film's "without moving" avoids the question by removing motion.
• SILENT: Firefly's Verse. No speed, distance or dilation is ever stated on screen; the light barrier applies to every ship in the Verse and the show never mentions it. The licensed supplement supplies the numbers the show does not
• SILENT: Halo: slipspace and the Shaw-Fujikawa translight engine (2001 onward). Sublight ships in the franchise are slow and the light barrier is never stated as the reason slipspace exists.
• SILENT: Star Wars: hyperspace (1977 onward). Characters say "jump to lightspeed" as if the ship were pushed to $c$, and no film says whether it is; the light barrier is neither stated nor evaded on screen.
• SILENT: Starman Jones: the congruencies (Heinlein 1953). The ship is driven to a computed speed at the anomaly and the text does not say how close to light speed that is; the question of the energy needed is never raised.
• SILENT: Warhammer 40,000: the Warp (1987 onward). Real-space travel is by plasma drives at modest speeds and the setting never states the light barrier as the reason the Warp is needed; sublight is simply slow.
• ENGAGES: Asimov's Foundation: the Jump through hyperspace (1942 onward). The defining passage states that travel through ordinary space cannot exceed light speed and draws the consequence (years between stars) before offering the Jump; the light barrier is on the page as the reason the drive exists.
• ENGAGES: Aurora's generation ship. The tenth-of-c ceiling, the sixty-year laser, the twenty-year deceleration and the fuel-less return are the plot; the light barrier's energy cost is the book's subject, though dilation at this speed is left unmentioned
• ENGAGES: Avatar's Venture Star. The film states the cryo duration to the day and the companion states the speed, the acceleration, the burn times and the dilation; the light barrier's cost is charged in years and in antimatter
• ENGAGES: Campbell's Islands of Space (1931): where the word came from. Chapter 1 states the light barrier as a property of space and proposes changing the space rather than pushing the ship harder; the constraint and the evasion are both on the page.
• ENGAGES: Death's End: curvature propulsion (Liu Cixin, 2010). The novel's ships reach c and stop, and the plot repeatedly turns on the fact that nothing goes faster; the register's ceiling is the novel's ceiling. A ship of finite mass reaching exactly c is itself a LOR-1 violation, since the energy diverges there, and the novel does not address that edge.
• ENGAGES: Ender's philotic ansible. The fleet takes decades at sublight; Mazer ages eight years for Earth's fifty; Ender is thirty-five after three thousand years. The light barrier for matter is the series' clock
• ENGAGES: Flight of the Navigator (1986). Faraday states the light barrier and the slowing of time near it; the film then goes beyond it and inherits the dilation as if it still applied. The constraint is named and built around, in the wrong way.
• ENGAGES: Futurama: the Planet Express ship's dark matter engines (1999 onward). The light barrier is named on screen, by Cubert, and answered twice, by raising c and by moving the universe instead of the ship; the constraint is engaged as a joke, and the second answer is the register's own escape from it.
• ENGAGES: Le Guin's ansible. NAFAL is the rule and its cost is the story: Semley's sixteen years, Rocannon's nine-year wait, Keng's eleven years. The unmanned FTL ships of Rocannon's World are the one exception and are stated as such
• ENGAGES: Mass Effect: element zero and the FTL drive (BioWare, 2007). The whole drive is an answer to LOR-1: the Codex says the light barrier is beaten by lowering mass and states the exponential cost. The answer is wrong in the way the register says, since the pole is in the Lorentz factor, but the constraint is named and built around.
• ENGAGES: Niven's Known Space: the Outsider hyperdrive and the blind spot (1966 onward). The setting's history is built on the light barrier: ramrobots and slowboats settled the colonies, the Outsiders travel at sublight on sails and the hyperdrive is a purchase that ended that era. The constraint is on the page as the thing the drive replaced.
• ENGAGES: Revelation Space lighthuggers. The "relativistic cruise ceiling" is the definition of the ship; dilation, reefersleep and Ultra longevity are the texture of every voyage
• ENGAGES: Spaceballs: ludicrous speed (1987). Light speed being too slow, and the named settings above it are the film's entire treatment of the light barrier: it is named as a speed and exceeded as a gag. The constraint is engaged by being mocked.
• ENGAGES: Star Trek: transwarp, quantum slipstream and the other beyond-warp drives. "Threshold" takes the light barrier to its limit, names warp 10 as infinite velocity and pays for crossing it with a biological penalty; the constraint is engaged on screen, as a horror beat.
• ENGAGES: Tau Zero's ramjet. The novel defines tau in its narration, tracks it chapter by chapter and makes its asymptotic approach to zero the story; the light barrier is engaged more directly than in any other entry of this class
• ENGAGES: The Forever War: collapsar jumps (Haldeman 1974). Ships approach collapsars at .9c and above and never exceed light speed; the whole novel is the price of that, kept in years.
• ENGAGES: The Skylark of Space (E. E. Smith, 1928). Chapter VII states the relativistic mass increase and the light-speed ceiling; Chapter VIII overrides them with a measured distance. The constraint is named and then dismissed, which is engagement of a kind.
• ENGAGES: Time for the Stars' telepathy. The Lorentz formula is stated by the ship's relativist, the ratios are tracked chapter by chapter, and the twin paradox is the book's structure: Pat ages to death while Tom stays young enough to marry his great-grandniece
• ENGAGES: Vinge's Zones of Thought: FTL only where physics permits it (1992). The Slow Zone is the light barrier stated as a regional law and kept without exception: ramjets near the boundary, a fleet stranded by the shift and a sequel (A Deepness in the Sky) whose ships crawl between stars for decades with relativistic time debt. The constraint is on the page and the plot turns on it.
• ENGAGES: Weber's Honorverse: hyper bands and Warshawski sails (1993 onward). The appendix states the light barrier's consequences in numbers: 0.8 c generation ships with 60 per cent dilation, a 0.6 c shielding cap in every band and a translation cap of 0.3 c; sublight is bounded on the page and the bands are the stated way round it.
• RULE: 2001: A Space Odyssey (1968): the Star Gate. Nothing is accelerated to light speed. The pod enters the slab at pod speed and the passage is a door, which is the L3 answer, and the novel's careful sublight mechanics for Discovery make the contrast deliberate.
• RULE: Andromeda: the slipstream. The ship transits out of normal space rather than accelerating; the stated rule is that slipstream is the only FTL and ordinary drives are sublight ("We're at 25 PSL" in the pilot's escape run, a percentage of light speed).
• RULE: Battlestar Galactica: the FTL jump (2004 series). The series states that ships do not accelerate to light speed and jump instead; the rule removes the object LOR-1 prices.
• RULE: Commonwealth: CST wormholes with trains through them (Hamilton 2004). Nothing in the Commonwealth accelerates toward light speed; trains roll through gateways and the starship falls through its wormhole. The rule is implicit in the design and kept.
• RULE: Contact: the Machine and the tunnel system (Sagan 1985, Zemeckis 1997). Nothing in the work is accelerated to light speed; the Machine's rings spin and the dodecahedron drops. The rule that the vehicle never flies fast is implicit in the design and is kept in both versions.
• RULE: Cordwainer Smith: planoforming, Space² and Space³. The ship is never accelerated to c; the stated rule is that it disappears into two dimensions and reappears, so kinetic energy never enters.
• RULE: Cowboy Bebop (1998): the astral gates. Ships fly to the ring at ordinary speed and are carried through; nothing is accelerated to light speed, and on the numbers shown nothing needs to be.
• RULE: Doctor Who: the TARDIS and the time vortex. The ship is never accelerated; the stated rule since 1963 is that it dematerialises and rematerialises, so no kinetic energy grows without bound.
• RULE: Elite Dangerous: the frame shift drive (Frontier Developments, 2014). Supercruise is described by the community and implied by the flight model as moving space rather than the ship, and the ship's engines never fire; the barrier is honoured by the design rather than pushed through.
• RULE: EVE Online: the warp drive (CCP Games, 2003). The lore places the ship inside a bubble that moves, rather than pushing the ship past light; the barrier is honoured by the stated mechanism.
• RULE: Event Horizon (1997): the gravity drive. Weir's rule: the ship does not move faster than light, the geometry does. The film states the constraint and its L3 answer in one exchange with Starck.
• RULE: Farscape (1999): wormholes, and starburst as a separate thing. Crichton's gravity-assist theory in "Premiere" is an attempt to go faster within ordinary physics, and the show's answer is that the wormhole took him, not the manoeuvre; the wormhole is a passage and nothing is accelerated to light speed.
• RULE: FTL: Faster Than Light, the jump drive as a game mechanic. The ship never accelerates; the stated rule is that engines provide evasion and charge rate, not speed, and the jump is a discontinuity.
• RULE: Guardians of the Galaxy Vol. 2 (2017): jump points. Ships fly to the access point at ordinary speed and are carried through, so nothing is accelerated to light speed; the film's jump-counting is the L3 answer to the entry.
• RULE: Homeworld: hyperspace cores and the Far Jumpers. Ships never accelerate to c; the stated rule is that engines move ships within a mission and only a core or hyperdrive moves them between systems.
• RULE: Hyperion: the farcasters (Simmons 1989). Nothing passes through a farcaster at speed; people walk and boats drift. The rule removes the object LOR-1 prices. The setting's Hawking-drive ships are a separate question, not scored here.
• RULE: Interstellar: the wormhole near Saturn (2014). The rule that the ship never approaches light speed is kept without exception: two years to Saturn, slingshots for orbit changes, the wormhole for the rest.
• RULE: Mass Effect: the mass relays (BioWare 2007 onward). The Codex's answer is the mass-free corridor: with mass removed, the kinetic-energy barrier LOR-1 prices is removed by fiat. The rule is stated in the Codex and is the same field logic as the drive core.
• RULE: No Man's Sky: the hyperdrive, warp cells and range. The ship never accelerates to c; the stated rule is that the pulse drive is for in-system travel and the hyperdrive is a separate system with a separate fuel.
• RULE: Outer Wilds (2019): Nomai warp cores. Nothing is accelerated to light speed; warps are passages and the Nomai's own ships fly at ordinary speed between them, which is the L3 answer to the entry.
• RULE: Passengers' Avalon. "50% of light speed" and 120 years are the stated rule of the ship, and the plot obeys them; the dilation that rule implies, about sixteen percent, is never mentioned
• RULE: Space Battleship Yamato: warp by wave motion engine. Yamato never accelerates to c; the stated rule is that ordinary thrust covers the legs between warps and the warp is a leap, so kinetic energy never grows without bound.
• RULE: Star Citizen: quantum drive and jump points. Quantum travel is a bubble, not a push, and the lore's speed ceiling keeps it under c; jump points are passages. Nothing is accelerated to light speed, and the two-mechanism design is the setting's way of saying so.
• RULE: Star Trek: warp drive (1966 onward). Warp 1 is the speed of light and the drive is stated to bend space rather than push the ship past light; the barrier is honoured by a stated rule of the fiction.
• RULE: Starfield (2023): the grav drive. In-system flight is slow and jumps are discrete displacements; nothing is accelerated to light speed, which is the L3 answer to the entry and is built into the game's two-mode travel.
• RULE: Stargate: the gate network (1994 film, SG-1 1997 onward). Nothing is accelerated; matter is converted at the event horizon and reconstituted at the far gate. The rule removes the object whose kinetic energy LOR-1 would price.
• RULE: Stargate: the ships' hyperdrives. Ships never accelerate to c; the stated rule is that sublight engines are for in-system work (Prometheus at a stated 110,000 miles per second) and the hyperdrive is a separate system.
• RULE: Stellaris: warp, hyperlane and wormhole (Paradox Development Studio, 2016). Each mode is described as bending or bypassing space rather than pushing a ship past light; the barrier is honoured by the stated design.
• RULE: Super Dimension Fortress Macross (1982): the space fold. The Macross moves at ordinary speed for the whole voyage home once the fold is gone; the fold is a jump and nothing is accelerated to light speed, which is the L3 answer to the entry and the series' whole premise after episode 3.
• RULE: The Alderson drive (Niven and Pournelle 1974). The ship never approaches light speed; sublight legs to the Alderson point and an instantaneous jump. The rule removes the object LOR-1 prices.
• RULE: The Expanse: the ring gates and the slow zone (Corey 2013 onward). The Epstein drive is a rocket and the setting keeps every ship below light speed; the rule that nothing accelerates past c is the foundation of the series and the gates are the only exception.
• RULE: The Hitchhiker's Guide to the Galaxy: the Infinite Improbability Drive and bistromathics. The ship is never accelerated to c; the Guide's stated rule is that it is at every point at once and then at one, so no kinetic energy grows without bound. The rule is a joke, and it does answer the row.
• RULE: The Lensman inertialess drive (E. E. Smith, 1934 onward). The books state that inert matter cannot reach c and then exempt free matter by definition; the exemption is a stated rule, not an engagement with why the ceiling exists.
• RULE: The Orville: quantum drive (2017 onward). The drive is stated to fold space and carry the ship in a bubble rather than push it past light; the barrier is honoured by a stated rule.
• RULE: Thor (2011): the Bifrost. Nothing is accelerated to light speed; the film names the passage a wormhole and shows travellers drawn through a column of light, which is the L3 answer to the entry.
• RULE: Wing Commander (1990) and the 1999 film: jump points. Ships fly to jump points at ordinary speed and are carried through; nothing is accelerated to light speed, which is the L3 answer to the entry and the reason jump points are terrain worth fighting over.
• RULE: Xenocide: travel through the Outside. The ship is never accelerated; the stated rule is that it leaves the universe and re-enters, so kinetic energy is never at issue. The series keeps LOR-1 for every other ship.

Sources

• Einstein, Ann. Phys. 322, 891 (1905), §10; Rindler, Relativity: Special, General, and Cosmological (2006), ch. 6 ✓ (Rindler chapter ⚠ v1)