arXiv subjects

Jacob Haqq-Misra

Publications and source records attributed to Jacob Haqq-Misra.

At least 19 recordsLinked to original sources

arXiv2026

Limits on Kinematic Inference from the PURSUE Airborne Sensor Videos

This paper analyzes the 112 sensor videos released under the PURSUE (Presidential Unsealing and Reporting System for UAP Encounters) initiative. Redactions to on-screen displays limit information available for identifying the reported unidentified anomalous phenomena (UAP). Converting the rate at which any object transits across part or all of a frame from pixels per frame to a physical velocity requires (1) the range to the object, (2) the velocity of the observing aircraft, (3) the aspect angle between the object's path and observer, and (4) the field angle of the camera. No PURSUE video provides this set of information. In one clip (DOW-UAP-PR113), the object crosses depression-angle markings, which allows reconstruction of the camera's field of view. Even this clip does not provide sufficient information to distinguish between a bird flying at close range and a large craft traveling at Mach 5 a kilometer away. A second clip (DOW-UAP-PR149) includes a vessel of known size in the frame, which can be used as a reference to calculate an upper bound of Mach 0.4 on the object's relative velocity. Without further information, the PURSUE sensor videos in their present form cannot fully resolve unidentified cases or conclusively indicate anomalous velocities.

physics.pop-ph↗

arXiv2026

Maximum Lifetime of the Vegetative Biosphere

We use a three-dimensional model to calculate steady-state climates at various intervals in Earth's future, across a parameter space of increasing insolation and decreasing CO$_2$ mixing ratio. Comparison with prior results shows an overestimation of warming by one-dimensional models when solar constant is increased and CO$_2$ mixing ratio is fixed. We consider two future trajectories as limiting cases: strong weathering, in which surface temperature remains constant but CO$_2$ is drawn down; and weak weathering, in which CO$_2$ remains constant and surface temperature increases. Under strong weathering, we find the conventional 10 ppm CO$_2$ starvation limit for C4 photosynthesis that occurs at 1.35 Gyr; however, we suggest that crassulacean acid metabolism (CAM) photosynthesis could persist below this limit and note that aquatic macrophytes can utilize dissolved bicarbonate if atmospheric CO$_2$ is low. If we take the CO$_2$ starvation limit at 1 ppm instead, then the vegetative biosphere could continue until 1.84 Gyr. Thermal limits apply instead under weak weathering, in which Earth would be too hot for most land plants at 1.68 Gyr (>323 K) and too hot for all land plants (>338 K) at 1.87 Gyr. These lifetimes approach the moist and runaway greenhouse limits for Earth. We discuss other possible mechanisms for extending the lifetime of Earth's biosphere, noting that both technological intervention and evolutionary processes could enable life to adapt to a brightening sun.

astro-ph.EP↗

arXiv2026

Exploring TRAPPIST-1 Climate States with an Energy Balance Model

This paper presents a version of the HEXTOR energy balance model that has been configured for the study of habitable terrestrial planets orbiting low-mass stars. The model is validated for rapidly-rotating Earth-like planets using latitudinal coordinates, which shows expected patterns of bistability. A tidally-locked coordinate transformation is then applied to the model, which is calibrated to match mean values of the minimum, average, and maximum surface temperatures from a general circulation model ensemble of TRAPPIST-1 e. This calibrated energy balance model is used to characterize the possible climate states of such a synchronously rotating planet across a parameter space of instellation and carbon dioxide partial pressure. These calculations suggest a state of partial ice cover for TRAPPIST-1 e and complete ice cover for TRAPPIST-1 f. TRAPPIST-1 e becomes fully ice-free only above ~0.4 bar CO$_2$, while TRAPPIST-1 f remains ice-covered unless CO$_2$ partial pressure approaches ~1.2 bar. This approach demonstrates the capability of a simplified one-dimensional model to study the climates of terrestrial planets in synchronous rotation, which can help guide more complex models and observations toward the most promising targets of interest.

astro-ph.EP↗

arXiv2026

Projections of Earth's Technosphere: Civilization Collapse-Recovery Dynamics and Detectability

How long a technological civilization remains active, and what determines whether it collapses or persists, is a central question for both projecting humanity's future and assessing the prevalence of detectable intelligence in the galaxy. We model collapse-recovery dynamics across ten plausible futures for Earth-originating civilization using a hybrid deterministic-stochastic simulation over a 1000-year window. The duty cycle, defined as the fraction of its total lifespan that a civilization is technologically active, ranges from ~0.38 to 1.00, with trajectory outcomes shaped by the interplay of governance structure, resource pressure, and hazard exposure. Several model parameters map onto actionable resilience levers, and modest improvements can qualitatively alter long-term trajectories. Sensitivity analysis reveals that the resource depletion rate and the post-collapse recovery fraction are consistently the most impactful levers across scenarios, suggesting that reducing resource consumption may be at least as important as mitigating existential hazards for avoiding civilizational collapse. We discuss implications for Earth's civilizational resilience and for the search for extraterrestrial technosignatures. We also derive an effective detectability duration that accounts for intermittent civilizational activity, and show that the apparent absence of extraterrestrial signals may reflect the prevalence of low-duty-cycle civilizations rather than the rarity of intelligent life.

physics.soc-ph↗

arXiv2026

Alternate states and intermingledness in complex high-dimensional systems

Many natural systems posses, and can transition between, multiple alternative states. For example, a climate ``tipping element'' is a climate component that can transition to an alternative steady state due to an external perturbation such as global warming. Despite the potential impact, existence of alternate states in realistic, complex simulations (e.g. climate models) remain poorly understood. Arguably a reason for this is the lack of applicable methodology that explicitly targets finite yet high-dimensional datasets. In this work we utilize recent progress in computational nonlinear dynamics to formulate a workflow that analyses potentially multi-state simulation data and decides algorithmically what are the alternate states contained within, if any are clearly distinguishable. The framework undergoes an optimization routine that showcases which observables in the data best differentiate the alternate states, and which ones do not differentiate at all, which could be used to guide monitoring and early-warning for multistable components in climate or ecosystems. Finally, once the alternate states have been found, we define an indicator called ``intermingledness''. It quantifies differences and similarities between alternate states, as well as for their basins of attraction (if applicable), across various diagnostic variables. We analyse and present results using three diverse climate datasets: Atlantic ocean circulation, atmospheric midlatitude flow, and habitability of exoplanets. The method is not exclusive to climatic data, but applicable to a variety of cases, including complex networks such as power grids or biological networks. We also provide easy-to-use open source code for applying the workflow to new data.

physics.ao-ph↗

arXiv2026

Framing the Possibility Space for Technosignature Searches

This paper develops a two-parameter matrix that can be used to describe four general strategies in the search for technosignatures. The first parameter is domain accessibility: can the technosignature be accessed within the spatial domain accessible to us today? The second parameter is recognizability: would the technosignature be recognizable to us if discovered today? This yields a matrix with four options that each comprise different search strategies. "Exploration" is the strategy for technosignatures that are accessible within our domain and recognizable. "Expansion" is the strategy for technosignatures that are recognizable but beyond our spatial domain. "Evolution" is the strategy for technosignatures that are accessible within our domain but unrecognizable. "Existence" is the strategy for technosignatures that are neither within our domain nor recognizable. The implications of these four options are discussed with relevance to the Fermi paradox and strategies for searching for technosignatures.

physics.pop-ph↗

arXiv2026

Cooperative Sovereignty on Mars: Lessons from the International Telecommunication Union and Universal Postal Union

As humans make ambitious efforts toward long-duration activities beyond Earth, new challenges will continue to emerge that highlight the need for governance frameworks capable of managing shared resources and technical standards in order to sustain human life in these hostile environments. Earth-based governance models of cooperative sovereignty can inform governance mechanisms for future Mars settlements, particularly regarding inter-settlement relations and the technical coordination required for multiple independent settlements to coexist. This study analyzes the International Telecommunication Union (ITU) and the Universal Postal Union (UPU), two of the oldest international organizations, which have successfully established evolving standards across sovereign nations. This analysis of the development and governance structures of these two organizations, and how they resolved key sovereignty issues, reveals principles that could be applicable to future settlements beyond Earth, particularly on Mars. Key insights include the strategic necessity of institutional neutrality, the management of asymmetric power relations, and the governance of shared resources under conditions of mutual vulnerability. The study distinguishes between a "Survival Layer" of technical standards essential for immediate safety and an "Operational Layer" governing economic and political activities, suggesting different governance approaches for each. Although some of these examples of cooperative sovereignty on Earth might not be sufficient for Mars due to its unique environment, lessons from the ITU and UPU case studies offer valuable strategies for designing flexible and sustainable governance models that can function from inception through explicit Earth-based coordination.

physics.soc-ph↗

arXiv2026

Limit cycles and the climate history of Mars

Evidence for fluvial features and standing liquid water indicate that Mars was a warmer and wetter place in its past; however, climate models have historically been unable to produce conditions to yield a warm early Mars under the faint young sun. Some models invoke thick greenhouse atmospheres to produce continuously warm conditions, but others have argued that available geologic evidence is more consistent with short-duration and transient warming events on an otherwise cold Mars. One possibility of harmonizing these perspectives is that early Mars experienced climate limit cycles that caused the climate to oscillate between short periods of warmth and prolonged periods of glaciation, due to modulation of greenhouse warming by the carbonate-silicate cycle. This study suggests that episodic limit cycling during the Noachian and Hesperian periods provides a hypothetical explanation for the timing and formation of fluvial features on Mars. A schematic time-forward trajectory of the full history of Mars is calculated using an energy balance climate model, which includes an active carbonate-silicate cycle, instellation changes due to the sun's main sequence evolution, variations in the obliquity of Mars, and supplemental warming from additional greenhouse gases beyond carbon dioxide alone. These calculations demonstrate the viability of a climate history for Mars involving episodic limit cycling to enable the formation of the valley networks at 4.1-3.5 Ga and delta features at 3.3-3.0 Ga, interspersed with cold stable climates and ending in the late Amazonian in a carbon dioxide condensation regime. This schematic climate trajectory provides a plausible narrative that remains consistent with available geologic data, and further exploration of warming mechanisms for the climate of Mars should consider the possibility of episodic transient events driven by carbonate-silicate limit cycling.

astro-ph.EP↗

arXiv2025

Projections of Earth's Technosphere: Strategies for Observing Technosignatures on Terrestrial Exoplanets

The search for technosignatures--remotely detectable evidence of extraterrestrial technology--draws upon examples from the recent history of Earth as well as projections of Earth's technosphere. Facilities like the Habitable Worlds Observatory (HWO) will significantly advance the feasibility of characterizing the atmospheres of habitable exoplanets at visible and near-infrared wavelengths, while other future mission concepts could extend this search to mid-infrared wavelengths. We draw upon a recently developed set of 10 self-consistent scenarios for future Earth technospheres as analogs for extraterrestrial technospheres, which we use to outline a stepwise technosignature search strategy, beginning with HWO and followed by other missions. We find that HWO could reveal elevated abundances of a CO$_2$ + NO$_2$ pair on planets with combustion and other large-scale industry, which could be observable in up to eight of the 10 scenarios. Follow-up radio observations could reveal narrowband directed transmissions, as occur in two of the scenarios. Further study involving direct detections at mid-infrared wavelengths with the Large Interferometer for Exoplanets could reveal spectral features from industry, such as the combinations of CO$_2$ + CFC-11/12 in four scenarios and CO$_2$ + CFC-11/12 + CF$_4$ in one scenario; two of these also include the N$_2$O + CH$_4$ + NH$_3$ triple from large-scale agriculture. Other mission concepts, such as a solar-gravitational-lens mission, could reveal large-scale surface features in two scenarios that would otherwise show no detectable technosignatures, while an interplanetary flyby or probe mission would be the most conclusive way to reveal the presence of technology on terrestrial exoplanets.

astro-ph.EP↗

arXiv2025

Functionality of Ice Line Latitudinal EBM Tenacity (FILLET). Protocol Version 1.1

The Functionality of Ice Line Latitudinal EBM Tenacity (FILLET) project is a CUISINES exoplanet model intercomparison project (exo-MIP) that compares various energy balance models (EBMs) through a series of numerical experiments. The objective is to establish rigorous protocols that enable the identification of intrinsic differences among EBMs that could lead to model-dependent results for past, current, and future EBM studies. Such efforts also provide the community with an EBM ensemble average and standard deviation, rather than a single model prediction, on benchmark cases typically used by EBM studies. These experiments include Earth-like planets at different obliquity, instellation, and carbon dioxide abundance. Here we update the v1.0 protocol (Deitrick et al., 2023) to accommodate the requirements of previously untested community models. In particular, we expand the range of carbon dioxide abundances for Experiment 4 to ensure any code will capture both snowball and ice-free end states. Additionally, participants are now required to report two ice edge latitudes per hemisphere to fully distinguish all climate states (snowball, ice caps, ice belts, and ice-free). The outputs described in FILLET protocol version 1.0 have also now been revised to include the maximum and minimum ice extent, in latitude, for each hemisphere, as well as the diffusion coefficient and outgoing longwave radiative flux.

astro-ph.EP↗

arXiv2025

Chemistry, Climate, and Transmission Spectra of TRAPPIST-1 e Explored with a Multimodel Sparse Sampled Ensemble

TRAPPIST-1 e is one of a few habitable zone exoplanets that is amenable to characterization in the near term. In this study our motivations are both scientific and technical. Our technical goal is to establish a multimodel sparse sampled ensemble approach for coherently exploring large unconstrained parameter spaces typical in exoplanet science. Our science goal is to determine relationships that connect observations to the underlying climate across a large parameter space of atmospheric compositions for TRAPPIST-1 e. We consider atmospheric compositions of N2, CO2, CH4, and H2O, with water clouds and photochemical hazes. We use a 1D photochemical model, a 3D climate model, and a transmission spectral model, filtered through a quasi-Monte Carlo sparse sampling approach applied across atmospheric compositions. While clouds and hazes have significant effects on the transmission spectra, CO2 and CH4 can be potentially detected in <10 transits for certain compositional and climate states. Colder climates have better prospects for characterization, due to being relatively dry and having fewer clouds, permitting transmission observations to probe more deeply into their atmospheres. CH4 volume mixing ratios of >$10^{-3}$ trigger strong antigreenhouse cooling, where near-IR absorption simultaneously creates an inversion in the stratosphere and reduces the stellar radiation reaching the planet surface. In such cases, interpreting the disk-averaged emission and albedo at face value can yield misleading conclusions, as here low albedo and high thermal emission are associated with cold planets. Future work will use our sparse sampling approach to explore broader parameter spaces and other observationally amenable exoplanets.

astro-ph.EP↗

arXiv2025

Wind Power as a Technosignature on M-dwarf Planets

We suggest that the large-scale deployment of wind turbines on an M-dwarf planet could produce observable technosignatures. Motivated by observations of hypersonic wind velocities on WASP-127 b, we note that the atmospheres of such planets could serve as vast reservoirs of energy for an extraterrestrial civilization. A large-scale deployment of wind turbines in a hypersonic environment would produce heated shock waves in the hypersonic stream, cause strong frictional heating from the rotation of the blades, and be a source of infrared radiation. We mention possible scenarios that could lead to the deployment of wind turbines on a gas giant and also note that similar features could exist on terrestrial M-dwarf planets. The idea that aerodynamic peculiarities could be a technosignature is worth keeping in mind as ground- and space-based exoplanet observations continue to improve.

physics.pop-ph↗

arXiv2025

K2-18b Does Not Meet The Standards of Evidence For Life

K2-18b, a temperate sub-Neptune, has garnered significant attention due to claims of possible biosignatures in its atmosphere. Low-confidence detections of dimethyl sulfide (DMS) and/or dimethyl disulfide (DMDS) have sparked considerable debate, primarily around arguments that their absorption features are not uniquely identifiable. Here, we consider all five questions from the astrobiology standards of evidence framework, starting with: Have we detected an authentic signal? To answer this, we analyzed publicly-available JWST observations of K2-18b using independent data reduction and spectral retrieval methodologies. Our comprehensive set of reductions demonstrates that the MIRI transit spectrum is highly susceptible to unresolved instrumental systematics. Applying different wavelength binning schemes yields a potpourri of planet spectra that then lead to a wide assortment of atmospheric interpretations. Consequently, we offer recommendations to help minimize this previously-underappreciated instrument systematic in future MIRI reductions of any exoplanet. While the MIRI binning scheme adopted by Madhusudhan et al. (2025) favors the presence of DMS/DMDS in K2-18b, we find that 87.5% of retrievals using our preferred MIRI binning scheme do not. When considering the full, 0.7 - 12 micron transit spectrum, we confirm the detection of CH4 and favor CO2, and find the presence of DMS and C2H4 to be interchangeable. Moreover, we find that the tentative presence of large features in the MIRI transit spectrum is in tension with the more robust, yet smaller, features observed in the near IR. We conclude that red noise -- rather than an astrophysical signal -- plagues the mid-IR data and there is, as yet, no statistically significant evidence for biosignatures in the atmosphere of K2-18b.

astro-ph.EP↗

arXiv2025

Can a Referendum Solve Problems of Shared Sovereignty on Mars?

Space exploration technology continues to expand humanity's reach beyond Earth, and even more ambitious efforts are striving to establish long-duration human settlements on Mars. The dependence of martian settlers on life-support infrastructure and on resupply missions from the host nation could create conditions for tyranny or lead to other extreme and uncontrollable situations, but such risks could be reduced by thinking about the possibilities for effective decision making on Mars before any settlement efforts actually occur. This paper examines the extent to which referendums could be used on Mars as a means of political decision-making and sovereignty adjudication. Our approach draws on three terrestrial case studies -- the Great Idaho Movement in the United States, the Catalan Independence Movement in Spain, and the Quebec Independence Movement in Canada -- as potential analogs for Mars governance. We recommend advance determination of the conditions under which a martian referendum would be recognized as a best practice for any agency seeking to establish a long-duration settlement on Mars. We suggest that referendums can reduce the likelihood of multiple authoritative political entities existing on Mars, which could provide a more procedural approach toward resolving governance issues between Earth and Mars. However, if Mars settlement is successful in establishing settlements on the scale of cities or larger, then other uniquely martian tools may evolve as a supplement or replacement to referendums.

physics.soc-ph↗

arXiv2024

Projections of Earth's Technosphere: Luminosity and Mass as Limits to Growth

Earth remains the only known example of a planet with technology, and future projections of Earth's trajectory provide a basis and motivation for approaching the search for extraterrestrial technospheres. Conventional approaches toward projecting Earth's technosphere include applications of the Kardashev scale, which suggest the possibility that energy-intensive civilizations may expand to harness the entire energy output available to their planet, host star, or even the entire galaxy. In this study, we argue that the Kardashev scale is better understood as a "luminosity limit" that describes the maximum capacity for a civilization to harvest luminous stellar energy across a given spatial domain, and we note that thermodynamic efficiency will always keep a luminosity-limited technosphere from actually reaching this theoretical limit. We suggest the possibility that an advanced technosphere might evolve beyond this luminosity limit to draw its energy directly from harvesting stellar mass, and we also discuss possible trajectories that could exist between Earth today and such hypothetical "stellivores." We develop a framework to describe trajectories for long-lived technospheres that optimize their growth strategies between exploration and exploitation, unlike Earth today. We note that analyses of compact accreting stars could provide ways to test the stellivore hypothesis, and we more broadly suggest an expansion of technosignature search strategies beyond those that reside exactly at the luminosity limit.

astro-ph.EP↗

arXiv2024

Projections of Earth's technosphere: Scenario modeling, worldbuilding, and overview of remotely detectable technosignatures

This study uses methods from futures studies to develop a set of ten self-consistent scenarios for Earth's 1000-year future, which can serve as examples for defining technosignature search strategies. We apply a novel worldbuilding pipeline that evaluates the dimensions of human needs in each scenario as a basis for defining the observable properties of the technosphere. Our scenarios include three with zero-growth stability, two that have collapsed into a stable state, one that oscillates between growth and collapse, and four that continue to grow. Only one scenario includes rapid growth that could lead to interstellar expansion. We examine absorption spectral features for a few scenarios to illustrate that nitrogen dioxide can serve as a technosignature to distinguish between present-day Earth, pre-agricultural Earth, and an industrial 1000-year future Earth. Three of our scenarios are spectrally indistinguishable from pre-agricultural Earth, even though these scenarios include expansive technospheres. Up to nine of these scenarios could represent steady-state examples that could persist for much longer timescales, and it remains possible that short-duration technospheres could be the most abundant. Our scenario set provides the basis for further systematic thinking about technosignature detection as well as for imagining a broad range of possibilities for Earth's future.

physics.soc-ph↗

arXiv2024

The challenge of detecting remote spectroscopic signatures from radionuclides

The characterization of exoplanetary atmospheres through transit spectra is becoming increasingly feasible, and technology for direct detection remains ongoing. The possibility of detecting spectral features could enable quantitative constraints on atmospheric composition or even serve as a potential biosignature, with the sensitivity of the instrument and observation time as key limiting factors. This paper discusses the possibility that future remote observations could detect the presence of radioactive elements in the atmospheres of exoplanets. Such radionuclides could arise from cosmogenic or geologic sources, as well as from industrial sources, all of which occur on Earth. The detection of radionuclides in an exoplanetary atmosphere could reveal important properties about the planet's geology or space environment, and potentially could serve as a technosignature. However, many radionuclides, including those from industrial sources, attach to aerosol or other particles that cannot be remotely characterized. Limited experimental and theoretical spectral data exist for long-lived radionuclides, but the sensitivity required to detect the spectral features of some known radionuclides would be at least several orders of magnitude greater than required to detect the spectral features of molecular oxygen. Present-day remote spectroscopic observing mission concepts at ultraviolet to mid-infrared wavelengths are not sensitive to discern the presence of radionuclides in exoplanetary atmospheres. Interplanetary fly-by or probe missions may be more likely to provide such data in the future.

astro-ph.EP↗

arXiv2024

A Model for Economic Freedom on Mars

The momentum of human spaceflight initiatives continues to build toward Mars, and technological advances may eventually enable the potential for permanent space settlement. Aspirations for sustaining human life in space must be predicated on human factors, rather than technological constraints alone, and advances in models of governance and ethics are necessary as human civilization becomes a spacefaring species. This paper presents an idealistic but feasible model for economic freedom on Mars, which is situated within a framework in which Mars has been designated as a sovereign juridical peer to Earth. Under such conditions, Mars could maintain monetary stability through full reserve banking and a restriction on exchange with any fractional reserve Earth currencies, with a volume of circulating currency that changes based on the total population within fixed capacity infrastructure. Mars could maintain long-term political stability by diffusing the ownership of capital on Mars, which would allow all citizens of Mars to draw sufficient wealth from a combination of capital ownership and labor to live a good life. This model could also support limited tourism on Mars, in which real goods are exchanged for services but currency transactions between planets are prohibited. This model demonstrates the potential for a viable and sustainable economy on Mars that could conceivably be implemented, including on a sovereign Mars but also in other scenarios of space settlement. More broadly, this model illustrates that ideas such as diffuse capital ownership and limited government can enable freedom in space, and numerous models beyond a centralized world space agency should be explored to ensure the optimal governance of the emerging space economy.

physics.pop-ph↗