What’s Next in Propulsion, Energy & Communications: 2030-2055

October 25, 2026
|In Field Effect
|By Tim Ventura

The world of the future is closer than you think. On October 24th, 2026, aerospace researcher Gary V. Stephenson outlined a future vision of fusion-powered propulsion, gravitational-wave communications, and even warp drives. His forecast for 2030–2055 explores how breakthroughs in compact, affordable energy and advanced physics could bring seemingly futuristic technologies closer to engineering reality.

Fusion Energy: The Technology That Could Make Everything Else Possible

Stephenson began with nuclear fusion because he considers it the most important enabling technology on his timeline. Fusion promises an enormous energy supply without the carbon emissions associated with fossil fuels, potentially transforming electricity generation, industrial manufacturing, and eventually spacecraft propulsion. However, the challenge isn’t simply initiating fusion reactions, which researchers have accomplished for decades. It’s maintaining a stable, sufficiently energetic plasma while extracting more useful energy than the complete system consumes. In February 2025, France’s WEST tokamak sustained a hydrogen plasma for 1,337 seconds, or 22 minutes and 17 seconds, using approximately 2 megawatts of radiofrequency heating and maintaining a plasma current of 215 kiloamperes. The experiment involved approximately 2.6 gigajoules of injected and extracted heating energy. Although an important achievement, WEST wasn’t demonstrating sustained net-positive fusion power. Its record involved maintaining an externally heated plasma, not operating a self-sustaining fusion reactor.

Stephenson also discussed alternative magnetic-confinement systems, particularly field-reversed configurations (FRCs) and spheromaks. Unlike conventional tokamaks, which require large toroidal vessels and external magnetic coils, these compact-toroid designs attempt to confine plasma using magnetic fields generated partly within the plasma itself. An FRC is an elongated plasma configuration dominated by poloidal magnetic fields, while a spheromak combines poloidal and toroidal fields in a more compact, roughly spherical arrangement. Stephenson cited approximately 40 milliseconds of confinement for FRCs and 3 milliseconds for spheromaks, although those figures shouldn’t be treated as current, directly comparable records without identifying the experiments and definitions involved. One practical application is Princeton’s Direct Fusion Drive, now also developed under the Starfire name, which proposes using a deuterium–helium-3 FRC reactor to produce electrical power and rocket thrust. The developers envision engines operating at roughly 1–10 megawatts, but the technology remains under development rather than representing a demonstrated flight-ready fusion engine.

A major focus of Stephenson’s discussion was aneutronic fusion, which attempts to minimize neutron production by selecting reactions that release much of their energy through charged particles. Conventional deuterium–tritium fusion produces a 14.1-megaelectronvolt neutron carrying approximately 80% of the reaction energy. Those neutrons penetrate structural materials, cause atomic displacement damage, and can activate components, creating substantial shielding and maintenance requirements. Deuterium–helium-3 fusion instead produces a proton and helium-4 nucleus, releasing approximately 18.3 megaelectronvolts, primarily as charged-particle energy. In principle, that could enable more direct electrical energy conversion and reduce neutron damage. However, deuterium–helium-3 isn’t completely neutron-free, because competing deuterium–deuterium reactions still occur. It also requires demanding plasma conditions, and helium-3 is extremely scarce on Earth. For compact propulsion applications, engineers would still need to manage fuel storage, superconducting magnets, radiation shielding, thermal conversion losses, and waste-heat rejection.

Artificial intelligence represents another opportunity to accelerate fusion research, and Stephenson suggested that increasingly advanced systems could identify plasma configurations that human researchers have overlooked. There is already experimental evidence that machine learning can help. In 2022, researchers working with DeepMind and the Swiss Plasma Center demonstrated reinforcement-learning control of the TCV tokamak, including unusual plasma shapes and simultaneous plasma configurations. AI-assisted systems can also contribute to disruption prediction, diagnostics, materials design, and optimization of magnetic control. Stephenson anticipates much greater advances from what he calls Super General Intelligence, although that remains a speculative expectation rather than an established engineering capability. The larger challenge is translating improved plasma physics into compact, reliable power systems. A fusion reactor useful for an aircraft or spacecraft would need not only a favorable energy balance, but also high power density, low structural mass, manageable radiation, and enough cooling capacity to operate continuously. In Stephenson’s outlook, solving those problems would begin opening doors to technologies that are currently impractical.

Magnetohydrodynamics: Flying Without Conventional Engines

By approximately 2035, Stephenson envisions significant improvements in magnetohydrodynamic propulsion, or MHD, which uses electromagnetic fields to manipulate electrically conducting fluids. In a conventional jet engine, energy is transferred to incoming air through compressors, combustion, and turbines. MHD systems attempt to transfer momentum directly using electric currents and magnetic fields. When a current flows through a conducting fluid in a magnetic field, the fluid experiences a Lorentz force perpendicular to both the current and the magnetic field. Engineers describe this interaction through the cross-product relationship between current density and magnetic flux density. By changing the orientation of the electrodes and magnets, they can theoretically produce lift, forward thrust, or localized aerodynamic forces. However, the electrical current passing through the plasma isn’t the same thing as the bulk velocity of the air, and creating sufficient electrical conductivity in ordinary atmospheric air is itself a major engineering challenge.

Stephenson highlighted work by French physicist Jean-Pierre Petit on MHD-controlled aircraft, including parietal accelerators and electromagnetic wall converters. These concepts envision placing electrodes and magnetic-field generators along the aircraft’s exterior to accelerate or decelerate nearby ionized air. Such arrangements could theoretically modify boundary layers, influence shock-wave formation, or replace conventional aerodynamic control surfaces with actively controlled plasma flows. Petit’s work includes unconventional aircraft configurations, such as cylindrical aerodynes and disk-shaped lifters that would interact with surrounding air electromagnetically rather than relying exclusively on wings and propellers. His published research describes experiments involving conductive fluids and plasma flows, including work with hot argon at temperatures approaching 10,000 kelvin. Those studies are valuable demonstrations of electromagnetic fluid control, but they don’t establish that a full-scale aircraft can produce enough efficient MHD lift or thrust to replace conventional propulsion.

Another concept involves using MHD technology to improve hypersonic air-breathing propulsion. At speeds exceeding Mach 5, shock waves, aerodynamic heating, and rapid airflow through the engine create major challenges for conventional combustors. An MHD energy-bypass system would place an electromagnetic generator ahead of the combustion chamber, extracting energy from the incoming ionized flow and reducing its speed. Electrical energy would then be routed around the combustor and returned to the exhaust using an MHD accelerator. The approach was explored in Russian AJAX vehicle studies and subsequent American research, including work by Ying Ming Lee, Paul Czysz, Claudio Bruno, and other investigators. However, adding electromagnetic machinery doesn’t automatically improve the engine’s performance. A 2002 NASA technical analysis by David Riggins found that the modeled MHD bypass engine performed worse than a conventional scramjet across the investigated Mach 8–12.2 range, largely because of additional pressure losses, thermodynamic irreversibility, and cooling requirements.

Despite those difficulties, MHD propulsion offers potentially useful capabilities beyond replacing jet engines. Electromagnetic control surfaces could reduce reliance on mechanical actuators, potentially improving control authority under conditions where exposed rudders, flaps, and other structures experience extreme heating and aerodynamic loading. Electric lift devices could also offer reduced mechanical noise compared with conventional rotors, although Stephenson acknowledged that they would be considerably less energy-efficient. A vehicle weighing one metric ton requires approximately 9,800 newtons of upward force merely to hover, before accounting for maneuvering, payload, and propulsion losses. Producing that force electromagnetically in air requires accelerating a substantial mass of fluid, regardless of whether the machinery contains rotating components. Compact high-field magnets, high-voltage systems, plasma generators, electrodes, insulation, and cooling equipment would all add mass. Fusion power could make high electrical consumption easier to tolerate, but it wouldn’t eliminate those structural and aerodynamic limitations.

Ionospheric Propulsion: Using the Atmosphere as Rocket Fuel

Moving beyond conventional atmospheric flight, Stephenson proposed an ionospheric drive that would collect particles from Earth’s upper atmosphere and accelerate them backward to produce thrust. The concept combines atmospheric intake, electric propulsion, and extremely high exhaust velocities, potentially reducing the need to carry onboard propellant. There is a genuine experimental precedent for part of this idea. In March 2018, the European Space Agency announced successful ground testing of an atmosphere-breathing electric thruster developed with European industrial partners. The system used a specially designed intake to collect atmospheric molecules under simulated conditions corresponding to approximately 200 kilometers altitude, where an orbiting spacecraft travels at roughly 7.8 kilometers per second. The collected molecules were electrically charged and accelerated to generate thrust. ESA demonstrated repeated ignition using atmospheric propellant, offering a potential path toward satellites capable of operating in very low Earth orbit without exhausting a finite supply of conventional propellant.

Stephenson’s proposed system would extend that principle much further, potentially supporting a vehicle transitioning from hypersonic atmospheric flight into orbit. However, atmosphere-breathing electric propulsion and a single-stage-to-orbit ionospheric vehicle operate under very different requirements. At 200 kilometers altitude, atmospheric density varies considerably with solar activity, local time, and geomagnetic conditions, and most available particles are neutral atoms or molecules rather than readily accelerated ions. Consider an illustrative density of one ten-billionth of a kilogram per cubic meter. An intake with a 10-square-meter collection area moving at 7.8 kilometers per second would encounter approximately 7.8 milligrams of atmospheric material each second. If every particle could be collected and expelled at 100 kilometers per second, the resulting ideal thrust would be approximately 0.78 newtons, requiring at least 39 kilowatts of exhaust kinetic power. Actual thrust would be lower after intake, ionization, acceleration, and other losses. Those figures illustrate why collecting atmospheric propellant is attractive for drag compensation but considerably more challenging as a primary launch propulsion system.

The most speculative part of Stephenson’s proposal involves accelerating exhaust particles to relativistic velocities. His presentation examined exhaust speeds ranging from 10% to 99.9% of the speed of light, discussing how relativistic momentum increases as particles approach light speed. At 10% of light speed, the Lorentz factor is approximately 1.005, representing only a small correction to classical momentum. At 90%, the factor rises to approximately 2.29, and at 99% it reaches approximately 7.09. However, an important numerical correction is necessary: at 99.9% of light speed, the Lorentz factor is approximately 22.37, not 700. A factor of approximately 707 requires a speed closer to 99.9999% of light speed. Stephenson’s backup slide also suggested that separately accelerating electrons to relativistic speeds might add approximately 2.4% to the thrust produced by heavier ions, but that result depends on the assumed particle species, velocities, beam currents, and electrical power. Those assumptions would need to be established before the percentage could be accepted as a general performance prediction.

The fundamental limitation is the relationship between exhaust velocity, momentum, and energy consumption. Higher exhaust velocity produces more momentum per kilogram of propellant, but it also requires much more energy. For an ideal electric rocket converting one megawatt entirely into exhaust kinetic energy, a nonrelativistic exhaust velocity of 100 kilometers per second could produce approximately 20 newtons of thrust. Increasing exhaust velocity to 10% of light speed reduces the available thrust to roughly 0.067 newtons at the same power level, even after accounting for relativistic effects. A 1-megawatt power source generating only a small fraction of a newton would be poorly suited to accelerating a substantial vehicle into orbit. High exhaust velocities become more attractive when propellant economy and accumulated velocity change matter more than immediate acceleration, especially during long-duration space missions. Stephenson acknowledged that his concept would require an enormous amount of compact electrical power, invoking the fictional miniature fusion reactor from Back to the Future as an analogy. The possibility of abundant fusion energy could justify further investigation, but the propulsion system would still need a realistic balance among collected mass, thrust, electrical efficiency, drag, and vehicle weight.

Gravitational-Wave Communications: A Backup for a World Without Satellites

Stephenson’s next forecast concerns gravitational-wave communications, a technology he has explored since at least 2003. His interest isn’t simply transmitting information through a different physical medium, but protecting critical infrastructure against disruptions to satellite navigation and communications. Modern positioning, navigation, and timing systems depend heavily on satellite constellations, including GPS, Galileo, and BeiDou. GPS satellites operate in medium Earth orbit at approximately 20,200 kilometers altitude, while many communications constellations occupy lower orbits. Stephenson raised the possibility of Kessler syndrome, a cascading sequence of orbital collisions that generates additional debris and increases the probability of further collisions. The hazard is particularly troublesome in orbital regions where atmospheric drag removes debris slowly. Although naturally occurring runaway collisions are less likely in sparsely populated higher orbits, deliberate satellite destruction during military conflict could create severe and persistent debris problems. Ground-based gravitational-wave transmitters, he suggested, might someday provide an independent communications channel that doesn’t depend on vulnerable orbital infrastructure.

Gravitational waves are disturbances in spacetime produced by accelerating mass distributions with changing quadrupole moments. In principle, sufficiently controlled sources could encode information into these disturbances, which propagate at the speed of light and interact extraordinarily weakly with ordinary matter. Stephenson’s 2003 paper, The Application of High Frequency Gravitational Waves to Communication, proposed investigating electromagnetic-to-gravitational-wave conversion using powerful laboratory equipment. One approach involves oscillating plasma inside a tokamak to generate a time-varying quadrupole mass distribution, potentially producing extremely weak gravitational radiation. His laboratory concept referenced the DIII-D tokamak at General Atomics in San Diego and proposed detectors influenced by the work of physicist Fangyu Li. The notional experimental arrangements involve demanding equipment, including powerful electromagnetic fields and sensitive receiving systems. In October 2026, Stephenson joined Andrew Beckwith and Fangyu Li in another paper examining possible gravitational-wave signatures from tokamak plasmas, discussing proposed detection of strains around 10 to the minus 26 at frequencies reaching 60 gigahertz. Those figures represent theoretical design considerations, not a demonstrated communications link.

The difficulty becomes apparent when compared with astronomical gravitational-wave detection. The first directly observed gravitational waves, detected by LIGO in September 2015, originated from the merger of two black holes and produced a peak strain of approximately one part in 10 to the 21st at Earth. Even that immense cosmic event produced an extraordinarily small disturbance, requiring kilometer-scale laser interferometers, sophisticated vibration isolation, and extensive signal processing. A laboratory transmitter would have vastly less mass and a much smaller changing quadrupole moment than a merging black-hole system. Moreover, the same weak interaction that allows gravitational waves to pass through Earth with little attenuation makes them extremely difficult to generate efficiently and detect. Stephenson discussed possible cosmological background strains around 10 to the minus 32 or 10 to the minus 33, but these shouldn’t be interpreted as universal noise floors without specifying frequency, bandwidth, and the underlying cosmological model. A credible communication system would need a complete link budget, including source strength, radiation efficiency, geometric spreading, detector sensitivity, noise, modulation bandwidth, and achievable data rate.

Stephenson was candid about the development schedule. His original 2003 roadmap anticipated prototype work beginning around 2015, but those milestones weren’t achieved. Nevertheless, he continues to consider approximately 2040 as a possible target for useful gravitational-wave communications. The proposed application is strategically interesting, but a working navigation backup would require considerably more than detecting a modulated signal. A positioning system needs sufficiently accurate timing, synchronized transmitters, known transmitter locations, and enough independent measurements to determine receiver position. It would also need affordable, reliable receiving hardware capable of operating outside specialized laboratories. Ground-based alternatives such as fiber-optic timing networks, terrestrial radio navigation, inertial systems, and resilient communications infrastructure already offer more mature ways to reduce satellite dependence. Gravitational-wave communications could eventually offer distinctive propagation advantages, but its feasibility currently depends on breakthroughs in gravitational-wave generation and detection rather than merely inexpensive electrical power.

The Forward Drive: Generating Gravity With a Superconducting Coil

For approximately 2045, Stephenson turned to an unconventional propulsion concept based on the Lense–Thirring effect, commonly known as frame dragging. General relativity predicts that rotating masses produce subtle changes in the surrounding gravitational field, effectively dragging local inertial reference frames along with their rotation. This effect has been measured around Earth. NASA’s Gravity Probe B mission used extraordinarily precise cryogenic gyroscopes to detect the geodetic and frame-dragging effects predicted by general relativity. Its final results, published in 2011, measured a frame-dragging drift of approximately 37.2 milliarcseconds per year, with an uncertainty of 7.2 milliarcseconds, compared with Einstein’s predicted 39.2 milliarcseconds per year. That represents an angular change of only about ten-millionths of a degree per year, illustrating just how weak the phenomenon is around a planet as massive as Earth. Stephenson’s question is whether laboratory equipment could generate a measurable version of the effect, and whether sufficiently advanced devices might ultimately produce useful gravitational forces.

The concept has historical roots in Robert L. Forward’s 1963 paper Guidelines to Antigravity, which examined possible methods of generating and controlling gravitational effects using known principles of general relativity. Forward investigated arrangements involving circulating mass flows, including toroidal configurations that resemble electromagnetic coils. Stephenson extended this approach in a 2019 paper with William Rieken and Atit Bhargava, titled Extended Cases of Laboratory Generated Gravitomagnetic Field Measurement Devices. Their proposal uses circulating superconducting currents in a toroidal winding, with the moving charge carriers serving as a source of mass current. The goal is to investigate whether extremely dense circulating currents could produce a detectable gravitational acceleration field near the coil’s center. The authors proposed using sensitive instruments, including quantum gravimeters, to search for the predicted effects. Detecting a local gravitational field would be scientifically significant, but it wouldn’t automatically demonstrate propellantless propulsion. A self-contained vehicle must still satisfy conservation of momentum, and internal forces acting among its components can’t ordinarily accelerate the vehicle’s center of mass.

The engineering requirements are extraordinary. Stephenson described a toroidal device approximately 10 meters across, containing an immense quantity of superconducting material wound into a tightly packed structure. His presentation estimated that a practical test system could require on the order of a billion miles of superconducting nanowire. He also discussed proposed carbon-based superconducting structures with characteristic dimensions near 25 nanometers and currents approaching 200 amperes. If those figures referred to a single 25-nanometer-diameter conductor, the resulting current density would exceed 400 quadrillion amperes per square meter, highlighting the need to distinguish individual filaments from larger composite conductors and theoretical material-performance estimates. Constructing such an assembly would require extraordinary advances in nanomaterial manufacturing, superconducting connections, thermal management, mechanical support, and quality control. Even if conductors with the required electrical properties became available, the magnetic forces acting within the winding could be enormous. A practical design would need to withstand those loads without deforming, losing superconductivity, or experiencing catastrophic structural failure.

Another concern is the energy stored within the superconducting magnetic field. Stephenson discussed configurations potentially storing terajoules of energy, comparable in stored energy to some industrial-scale storage systems. One terajoule represents approximately 278 megawatt-hours, equivalent to the chemical energy of roughly 239 metric tons of TNT. That doesn’t mean a quench would release the energy with the same explosive efficiency as TNT, but it illustrates the magnitude of the potential safety problem if a large fraction were dissipated rapidly. In superconducting magnetic energy storage, or SMES, circulating currents can preserve substantial magnetic energy with relatively low resistive losses, but quench protection must safely redirect and dissipate that energy when superconductivity fails. Stephenson suggested placing a future experimental device deep underground and considered whether advanced materials might amplify gravitational coupling, allowing a smaller apparatus. The storage technology and mechanical challenges are legitimate engineering research areas. The proposed gravitational amplification and propulsion effects, however, remain unverified, and Stephenson explicitly acknowledged that the intended laboratory effect hasn’t been measured in this configuration.

Warp Drives: Turning Spacetime Into a Propulsion System

By approximately 2050, Stephenson’s timeline moves beyond unconventional electromagnetic propulsion and toward manipulating the geometry of spacetime itself. His discussion centered on the Alcubierre warp drive and related solutions developed using Einstein’s field equations. In 1994, physicist Miguel Alcubierre proposed a mathematical spacetime geometry in which a localized region, often called a warp bubble, could move relative to distant observers while the spacecraft inside remained locally at rest. Rather than accelerating a spacecraft through space in the conventional sense, the concept changes the geometry of the surrounding spacetime. Later researchers, including José Natário, developed related solutions with different geometric properties and velocity-field structures. Stephenson also discussed accelerated warp-drive configurations and computational tools that allow researchers to explore proposed metrics. These studies investigate solutions permitted by mathematical models of general relativity, but they don’t establish that the required physical systems can be constructed.

A central difficulty is determining what matter and energy distribution could produce the desired spacetime geometry. Einstein’s equations connect spacetime curvature with stress-energy, including mass, momentum, pressure, and other physical contributions. Traditional superluminal warp-drive solutions generally require regions of negative energy density or violations of classical energy conditions, presenting serious theoretical and engineering obstacles. Quantum field theory permits certain negative-energy effects under restricted circumstances, but no demonstrated technology can create and control the macroscopic stress-energy distributions required for a spacecraft-scale superluminal warp bubble. Some more recent theoretical approaches investigate subluminal configurations, alternative geometries, or reduced energy-condition violations. These may clarify which parts of the problem arise from particular mathematical assumptions, but they haven’t produced an experimentally validated warp propulsion mechanism. Even if a suitable physical source were discovered, engineers would still need to create the field, control its geometry, manage instabilities, and understand how a spacecraft could safely enter, accelerate within, and leave the resulting configuration.

Stephenson also examined whether metamaterials might offer a path toward stronger interactions between electromagnetic fields and gravity. Metamaterials are engineered structures whose internal geometry gives them electromagnetic properties unavailable in ordinary bulk materials, including unusual effective permittivity, permeability, and even negative refractive indices over selected frequency ranges. Researcher Jack Sarfatti has proposed that certain electromagnetic material responses could modify gravitational coupling, introducing an additional susceptibility term into the gravitational field equations. In Stephenson’s presentation, this possibility was discussed as a potential way to magnify gravitomagnetic effects or make warp-drive engineering less demanding. The distinction is that changing how an electromagnetic wave propagates through a medium doesn’t necessarily change the actual curvature of spacetime. Optical analogues can reproduce mathematical features of curved spacetime, but they aren’t equivalent to generating real gravitational fields. Sarfatti’s proposed gravitational enhancement requires independent theoretical validation and direct experimental evidence before it can be treated as an established physical mechanism.

The possibility that some of these technologies might be related to unidentified anomalous phenomena also entered the discussion. Stephenson volunteers with the Scientific Coalition for UAP Studies and has examined proposed warp-drive configurations as possible explanations for unusual reported vehicle behavior. He referenced the 2004 USS Nimitz encounter, in which military personnel reported an unidentified object commonly called the Tic Tac, and discussed speculation that advanced materials or spacetime engineering could account for such observations. These comparisons are hypotheses rather than demonstrations of an underlying propulsion mechanism. Publicly available observations don’t establish that the object employed a warp drive, metamaterial gravitational amplifier, or any other particular advanced propulsion system. Nevertheless, Stephenson considers the mathematical classification of possible warp geometries useful independent of their proposed application. By identifying what each model requires in terms of geometry, stress-energy, and acceleration, researchers can evaluate whether any hypothetical system offers a physically plausible route to propulsion.

Gravitational Beams, Wormholes, and the Possibility of Controlling Distance

Stephenson extended the discussion beyond spacecraft propulsion to the possibility of producing localized gravitational forces capable of moving distant objects. He referenced a 2021 paper by Jessica Santiago, Sebastian Schuster, and Matt Visser titled Tractor Beams, Pressor Beams and Stressor Beams in General Relativity. Their work examines mathematical spacetime geometries that could produce three distinct effects: attracting an object toward a source, pushing an object away, or applying differential forces that stretch an object. The authors constructed these solutions using techniques related to warp-drive metrics, showing that general relativity can mathematically describe the desired motions. A tractor beam would require a controlled geometry producing net attraction, while a pressor beam would generate repulsion. A stressor beam would produce opposing forces across an object’s structure. These are mathematical constructions, not laboratory demonstrations, and the authors found that the modeled beams require violations of classical energy conditions.

The engineering implications would be considerable even if an appropriate physical mechanism became available. A gravitational tractor beam would need to manipulate the motion of an object without directly attaching to it, requiring spatial and temporal control over the relevant gravitational field. Unlike an electromagnetic beam interacting with a charged surface or conducting material, a gravitational effect would act on mass-energy and could potentially penetrate ordinary materials. However, any practical system would need a physical source for the spacetime curvature, a way to direct the desired interaction, and a means of controlling the resulting forces. Producing a strong gravitational gradient across a relatively small object could also create damaging tidal stresses. A useful transport system would therefore require more than demonstrating attraction or repulsion: it would need precise force control, predictable interactions with nearby matter, and an energy budget that doesn’t exceed the value of the transported payload. The theoretical studies provide a way to describe the desired physics, but they don’t yet identify a feasible technology for generating it.

Wormholes represent another extension of spacetime engineering discussed in the presentation. General relativity permits mathematical geometries connecting otherwise distant regions of spacetime, often described as Einstein–Rosen bridges. Such structures appear in certain black-hole solutions, although the original Einstein–Rosen bridge isn’t a traversable passage that a spacecraft could simply fly through. Later theoretical work investigated traversable wormholes, generally requiring unusual stress-energy distributions to prevent the throat from collapsing. If a stable, traversable wormhole could exist, it might provide a shortcut between distant locations without requiring a spacecraft to travel conventionally across all the intervening space. However, creating or maintaining such a structure would present challenges far beyond those associated with ordinary spacecraft propulsion. Researchers would have to explain how to generate the required spacetime geometry, keep it stable, avoid destructive tidal forces, and ensure that matter could safely pass through it. No experimentally verified traversable spacetime wormhole has been produced or observed.

Stephenson also explored the relationship between wormholes and quantum entanglement, particularly the ER = EPR conjecture. The proposal suggests a deep connection between Einstein–Rosen bridges and Einstein–Podolsky–Rosen quantum entanglement, potentially linking the geometry of spacetime to quantum information. This has become an important theoretical research topic because entanglement may help explain how spacetime geometry emerges in certain approaches to quantum gravity. However, ordinary entangled particles don’t provide a controllable communications channel that can transmit information faster than light. Quantum teleportation, for example, requires both preexisting entanglement and a classical communications channel to reconstruct the transferred quantum state. Experiments using quantum processors have simulated aspects of traversable-wormhole dynamics in theoretical models, but those experiments don’t constitute the creation of physical portals through spacetime. The distinction is important: the possible relationship between quantum information and spacetime geometry could reshape fundamental physics without necessarily producing a practical wormhole communications network or transportation system.

Quantum Cosmology: Could Space and Time Be Emergent?

The final stage of Stephenson’s timeline, extending toward approximately 2055, concerns quantum gravity and quantum cosmology. Rather than concentrating on a particular propulsion device, he explored how a deeper understanding of the universe might change the physical assumptions behind future technologies. He recommended the fourth edition of Claus Kiefer’s Quantum Gravity, which examines attempts to reconcile quantum mechanics with general relativity. One major conceptual difficulty is the role of time. Conventional quantum mechanics generally describes how physical states evolve with respect to an external time parameter, while general relativity treats time as part of a dynamical spacetime geometry. In certain formulations of quantum gravity, the familiar external time variable no longer appears in the fundamental equation in the same way. This has motivated research into whether time is emergent, arising from correlations or changes among quantum states rather than existing as an independent universal background. Such ideas remain theoretical and don’t establish that time travel or communication with the past is physically possible.

Quantum cosmology also raises questions about what happened at the beginning of the universe and whether the Big Bang represents an absolute beginning. Stephenson discussed cyclic and ekpyrotic cosmological models, including the possibility that cosmic contraction could be followed by a bounce rather than an unavoidable singularity. The terminology is important: a Big Crunch generally refers to a contracting universe approaching an extreme state, while a Big Bounce describes a transition from contraction to expansion. Ekpyrotic and cyclic models attempt to explain cosmic evolution using mechanisms that can differ substantially from conventional inflationary cosmology. Some versions involve interactions between higher-dimensional structures or fields, while others use effective descriptions of contraction and expansion. These models remain under investigation, and none has established that our observable universe necessarily emerged from a previous contracting phase. Measurements of cosmic expansion, primordial element abundances, large-scale structure, and the cosmic microwave background provide important constraints on proposed alternatives. Future progress would require models that produce testable predictions distinguishable from established cosmological explanations.

One of the more experimentally accessible questions involves determining whether gravity itself has quantum properties. Stephenson discussed the MAST-QG collaboration, which is investigating whether gravitational interactions can generate measurable entanglement between small masses. The proposed experiments involve tiny diamonds prepared in carefully controlled quantum states, with researchers attempting to isolate gravitationally mediated interactions from ordinary electromagnetic forces and environmental disturbances. The underlying idea is that two objects interacting through a quantum gravitational field could develop correlations that certain classical descriptions of gravity cannot explain. Experimental challenges include maintaining quantum coherence, controlling surface charges, suppressing vibration, and measuring extremely weak interactions between small masses. Stephenson also referred to the August 2026 SLAC Summer Institute, whose theme was Quantum Probes for a Quantum Universe, where researchers discussed quantum sensors and possible tests of fundamental physics. These investigations are important because a convincing demonstration of gravity-mediated entanglement could provide evidence relevant to the quantum nature of gravity, although interpreting such an experiment would still require careful consideration of competing theoretical models.

Stephenson closed with an even broader possibility: that space, time, matter, and the apparent continuity of the physical world might emerge from a more fundamental computational structure. He referenced physicist David Maker’s proposals involving an evolving fractal universe and described illustrations he developed in 2014 to visualize some of those ideas. Computational and information-theoretic approaches to physics offer alternative ways of thinking about how familiar physical laws might emerge from underlying mathematical relationships, but Maker’s particular model hasn’t been established as a verified description of nature. Stephenson suggested that advances in quantum gravity might eventually influence how we understand consciousness, causality, and the relationship between observation and physical reality, extending into ideas such as remote viewing and unconventional experiences of time. These possibilities remain speculative, and current physics doesn’t establish that consciousness can travel backward through time or obtain information through such mechanisms. Yet the broader scientific question is legitimate: if space and time aren’t fundamental, a successful quantum theory of gravity could change our understanding of what is physically possible.

From Scientific Possibility to Engineering Reality

Across the presentation, Stephenson returned repeatedly to the relationship between scientific knowledge and technological capability. Many of the proposed advances rely on physical principles that are already understood in at least some form. Nuclear fusion has been demonstrated, although commercial fusion electricity and practical fusion propulsion remain challenging. Magnetohydrodynamic forces are routinely studied and used in specialized equipment, but building efficient aircraft propulsion systems around those forces is another matter. Gravitational waves have been directly detected, yet generating detectable laboratory waves and encoding useful information in them would require capabilities far beyond current demonstrations. Frame dragging is a measured consequence of general relativity, while attempts to generate useful artificial gravitational fields remain theoretical. These distinctions matter because confirming that a physical phenomenon exists is only the beginning of developing an engineered system around it.

The importance of energy is also more complicated than simply making electricity inexpensive. A stationary power plant can use massive shielding structures, large cooling systems, and extensive supporting infrastructure, while an aircraft or spacecraft must carry much of its equipment. Engineers measure propulsion-system performance through quantities such as thrust-to-weight ratio, specific impulse, electrical efficiency, thermal loading, and specific power, commonly expressed in kilowatts per kilogram. A one-megawatt reactor weighing 100 metric tons offers little advantage to a conventional aircraft, regardless of its fuel economy. A much smaller reactor producing comparable power could be transformative, but only if its magnets, shielding, controls, and heat rejection systems fit within the same mass budget. Stephenson’s anticipated breakthroughs therefore involve several interdependent technologies rather than fusion alone. Improvements in superconductors, advanced manufacturing, high-temperature materials, autonomous control, and thermal management could be as important as the reactor itself.

Another recurring theme is the possibility that artificial intelligence could accelerate progress in areas that have resisted conventional engineering approaches. AI already assists researchers with complex control problems, numerical simulations, and optimization tasks, but physical systems must still obey experimentally verified constraints. Better computational methods can identify promising magnetic configurations, evaluate novel materials, and help design experiments, yet a simulation can’t substitute for measuring thrust, heat transfer, gravitational acceleration, or energy conversion in an actual device. Stephenson’s most speculative proposals would benefit particularly from focused experimental milestones. A laboratory gravitational-wave link would be more informative than a communications roadmap built around assumed source strengths. A reproducible gravitomagnetic measurement would provide a stronger foundation for future field-propulsion investigations than another large-scale coil design. Similarly, a controlled experiment showing gravitational amplification from an engineered material would be an important first step toward evaluating whether metamaterials have applications beyond electromagnetism.

Stephenson described his forecast as one possible timeline rather than a prediction of inevitable technological progress, and the presentation’s most valuable contribution may be the sequence of questions it raises. Which technologies are limited primarily by power, materials, and engineering complexity? Which require entirely new experimental capabilities? And which depend on theoretical assumptions that haven’t yet been established? The answers will determine whether the coming decades produce incremental improvements to familiar propulsion systems or fundamental changes in how vehicles interact with matter, energy, and spacetime. Fusion and advanced electromagnetic propulsion offer comparatively direct paths toward engineering development, while gravitational-wave communications, artificial gravity, and warp drives require increasingly ambitious breakthroughs. The dates on Stephenson’s timeline may ultimately prove optimistic, conservative, or simply wrong. What matters is whether researchers can turn the underlying ideas into measurable effects, repeatable experiments, and eventually technologies capable of performing useful work.

References

Gary Stephenson’s APEC Presentation and Research

Fusion Energy and Advanced Plasma Confinement

Magnetohydrodynamics and Ionospheric Propulsion

Gravitational-Wave Communications and Detection

Gravitomagnetism and the Forward Drive

Warp Drives and Gravitational Beams

Wormholes and Quantum Entanglement

Quantum Gravity and Quantum Cosmology