Future Cone Research Articles

Entanglement generation from athermality

We investigate the thermodynamic constraints on the pivotal task of entanglement generation using out-of-equilibrium states through a model-independent framework with minimal assumptions. We establish a necessary and sufficient condition for a thermal process to generate bipartite qubit entanglement, starting from an initially separable state. Consequently, we identify the set of system states that cannot be entangled, when no external work is invested. In the regime of infinite temperature, we analytically construct this set; while for finite temperature, we provide a simple criterion to verify whether any given initial state is or is not entangleable. Furthermore, we provide an explicit construction of the future thermal cone of entanglement—the set of entangled states that a given separable state can thermodynamically evolve to. We offer a detailed discussion on the properties of this cone, focusing on the interplay between entanglement and its volumetric properties. We conclude with several key remarks on the generation of entanglement beyond two-qubit systems, and discuss its dynamics in the presence of dissipation. Published by the American Physical Society 2024

Improved decay estimates and C2-asymptotic stability of solutions to the Einstein-scalar field system in spherical symmetry

We investigate the asymptotic stability of solutions to the characteristic initial value problem for the Einstein (massless) scalar field system with a positive cosmological constant. We prescribe spherically symmetric initial data on a future null cone with a wider range of decaying profiles than previously considered. New estimates are then derived in order to prove that, for small data, the system has a unique global classical solution. We also show that the solution decays exponentially in (Bondi) time and that the radial decay is essentially polynomial, although containing logarithmic factors in some special cases. This improved asymptotic analysis allows us to show that, under appropriate and natural decaying conditions on the initial data, the future asymptotic solution is differentiable, up to and including spatial null-infinity, and approaches the de Sitter solution, uniformly, in a neighborhood of infinity. Moreover, we analyze the decay of derivatives of the solution up to second order showing the (uniform) [Formula: see text]-asymptotic stability of the de Sitter attractor in this setting. This corresponds to a surprisingly strong realization of the cosmic no-hair conjecture.

RPGR: Deep Phenotyping and Genetic Characterization With Findings Specific to the 3'-end of ORF15.

To describe a group of patients with retinitis pigmentosa GTPase regulator (RPGR)-related retinopathy with a tapetal-like retinal sheen and corresponding changes in the reflectivity of the ellipsoid zone on optical coherence tomography (OCT) imaging. A retrospective case series of 66 patients with a disease-causing variant in RPGR was performed. An expert examiner, masked to patient demographics, clinical evaluations, and specific RPGR variant, analyzed color fundus photographs for the presence of a tapetal-like retinal sheen and assessed OCT images for the presence of an abnormally broad hyper-reflective band in the outer retina. Longitudinal reflectivity profiles were generated and compared with healthy controls. Twelve patients (18.2%) had a retinal sheen on color images that cosegregated with an abnormally broad hyper-reflective ellipsoid zone band on OCT imaging. Three-fourths of these patients were male, had a cone-rod dystrophy, and had pathogenic RPGR variants located toward the 3'-end of ORF15. This group had a different longitudinal reflectivity profile signature compared with controls. After a period of prolonged dark adaptation, the abnormal hyper-reflective band on OCT became less apparent, and the outer retinal layers adopted a more normal appearance. RPGR-related retinopathy should be considered for males presenting with retinal sheen, abnormal ellipsoid zone hyper-reflectivity, and cone or cone-rod dysfunction on ERG, and pursued with molecular testing. Our results have implications for understanding the role of the C-terminal domain encoded by RPGR ORF15 in the phototransduction cascade. Further, the findings may be important to incorporate into both inclusion criteria and outcome measure developments in future RPGR-related cone or cone-rod dystrophy clinical trials.

Exploring the Future Design Approach to Ageing Based on the Double Diamond Model

As the global trend of aging continues to intensify, there will inevitably be more complex and diverse aging-related problems. Designers have a responsibility to explore the possible outcomes of the future and solve the ageing-related problems that will be faced in the future. Based on the Future Cone, the Double Diamond Model and the IDEO Method Cards, this study proposes a new model to guide the design practice of future aging issues in the context of aging. With the aim of validating and refining the framework, an ageing designer workshop was held, in which participants were asked to imagine, explore and express ideas about future ageing-related issues. The workshop was used to refine the proposed model. Specifically, the model includes a future concept, a design guidance process based on the Double Diamond Model, and tools that can be applied at all stages of design, which can help designers to generate ideas and solutions for future aging problems, as well as collectively lead society toward a more desirable future. Moreover, this study explores broader directions for the development of the model and provides a reference for continued research into this topic in the future.

Impact of herbivory by Zerenopsis lepida (Lepidoptera: Geometridae) on the endangered Encephalartos eugene-maraisii under field conditions

Encephalartos eugene-maraisii is an endangered, endemic plant in the Waterberg Mountain range of South Africa. This is the first report of herbivory by Zerenopsis lepida (Lepidoptera: Geometridae) on natural populations of E. eugene-maraisii. The impact of herbivory by folivorous arthropods on this cycad species has not been studied before. This study aimed to determine the incidence and intensity of Z. lepida herbivory on E. eugene-maraisii under field conditions. Local plant dynamics were studied by recording the plant location, sex, size and phenological stage for each plant. Damage surveys were carried out over two consecutive seasons (2020–2021 and 2021–2022). Leaf damage was assessed on 227 plants comprising 692 stems. Approximately 40% of the stems had signs of leaf herbivory by Z. lepida and 10% of the total leaf area was removed by Z. lepida larvae. Less herbivory was recorded in areas where plants synchronously produced new leaf flushes compared to areas with asynchronous leaf flushes. Greater apparency of plants led to a greater incidence of herbivory and level of damage. Repeated damage to plants may delay future leaf and cone flushing events and contribute to the threat against this cycad species.

Geometric structure of thermal cones.

The second law of thermodynamics imposes a fundamental asymmetry in the flow of events. The so-called thermodynamic arrow of time introduces an ordering that divides the system's state space into past, future, and incomparable regions. In this work, we analyze the structure of the resulting thermal cones, i.e., sets of states that a given state can thermodynamically evolve to (the future thermal cone) or evolve from (the past thermal cone). Specifically, for a d-dimensional classical state of a system interacting with a heat bath, we find explicit construction of the past thermal cone and the incomparable region. Moreover, we provide a detailed analysis of their behavior based on thermodynamic monotones given by the volumes of thermal cones. Results obtained apply also to other majorization-based resource theories (such as that of entanglement and coherence), since the partial ordering describing allowed state transformations is then the opposite of the thermodynamic order in the infinite temperature limit. Finally, we also generalize the construction of thermal cones to account for probabilistic transformations.

Vacuum thermal effects in flat space-time from conformal quantum mechanics

The generators of radial conformal symmetries in Minkowski space-time can be mapped to the generators of time evolution in conformal quantum mechanics. Within this correspondence we show that in conformal quantum mechanics the state associated to the inertial vacuum in Minkowski space-time has the structure of a thermofield double. Such state is built from a bipartite “vacuum state”, the ground state of the generators of hyperbolic time evolution, which cover only part of the time domain. When time evolution is restricted to a finite time domain one obtains the temperature perceived by static diamond observers in the Minkowski vacuum. When time evolution is determined by dilations, covering only half of the time line, the temperature of the thermofield double corresponds to the non-vanishing temperature perceived by Milne observers whose proper time evolution is confined to the future cone (Milne universe) of Minkowski space-time. The two pictures are related by a conformal transformation on the real line. Our result provides a purely group theoretical derivation of the Milne and diamond temperatures and shows that the fundamental ingredient for vacuum thermal effects is the presence of a horizon rather than acceleration.

Global solutions to the spherically symmetric Einstein-scalar field system with a positive cosmological constant in Bondi coordinates

We consider a characteristic initial value problem, with initial data given on a future null cone, for the Einstein (massless) scalar field system with a positive cosmological constant, in Bondi coordinates. We prove that, for small data, this system has a unique global classical solution which is causally geodesically complete to the future and decays polynomially in radius and exponentially in Bondi time, approaching the de Sitter solution.

Lightlike manifolds and Cartan geometries

Lightlike Cartan geometries are introduced as Cartan geometries modelled on the future lightlike cone in Lorentz-Minkowski spacetime. Then, we provide an approach to the study of lightlike manifolds from this point of view. It is stated that every lightlike Cartan geometry on a manifold N provides a lightlike metric h with radical distribution globally spanned by a vector field Z. For lightlike hypersurfaces of a Lorentz manifold, we give the condition that characterizes when the pull-back of the Levi-Civita connection form of the ambient manifold is a lightlike Cartan connection on such hypersurface. In the particular case that a lightlike hypersurface is properly totally umbilical, this construction essentially returns the original lightlike metric. From the intrinsic point of view, starting from a given lightlike manifold (N, h), we show a method to construct a family of ambient Lorentzian manifolds that realize (N, h) as a hypersurface. This method is inspired on the Feffermann-Graham ambient metric construction in conformal geometry and provides a lightlike Cartan geometry on the original manifold when (N, h) is generic.

Interactions between Hlawka Type-1 and Type-2 quantities

The classical Hlawka inequality possesses deep connections with zonotopes and zonoids in convex geometry, and has been related to Minkowski space. We introduce Hlawka Type-1 and Type-2 quantities, and establish a Hlawka-type relation between them, which connects a vast number of strikingly different variants of the Hlawka inequalities, such as Serre's reverse Hlawka inequality in the future cone of the Minkowski space, the Hlawka inequality for subadditive function on abelian group by Ressel, and the integral analogs by Takahasi et al. Besides, we announce several enhanced results, such as the Hlawka inequality for the power of measure function. Particularly, we give a complete study of the Hlawka inequality for quadratic form which relates to a work of Serre.

A return to Hayman Island: revisiting Australia’s only recorded cone snail fatality after 85 years

The death of Charles Hugh Garbutt from a cone snail ‘sting’ inflicted at Hayman Island on the Great Barrier Reef marked both a family tragedy and an important moment in Australian medical and malacological history. However, aside from newspaper reports and the few witness statements given at the coronial inquiry, the events of that day in June 1935 and its immediate aftermath have never been critically evaluated. As memories of what happened have either faded or been partly distorted with the passage of time, the fatality today remains only a footnote in the history of studies on the Conidae and their complex, pharmaceutically-valuable venoms. The species involved, Conus geographus Linnaeus, 1758, is now recognised as the most dangerous to humans of the Conidae and responsible for most and possibly all recorded fatalities. After 85 years, the case is revisited using available evidence including newspaper reports, relevant scientific and popular literature, witness statements, archival documents and the actual specimen responsible for the fatality. While tragic and probably avoidable, the death, via its extensive coverage by the press, undoubtedly has helped to save lives by educating a public largely unaware of the dangers from something as seemingly harmless as a sea snail. It is also concluded that Charles Garbutt, when all factors are considered, was most unfortunate to have lost his life in the way that he did. For future cone envenomations it is recommended that photography (if possible) of the specimen involved would assist both in patient reassurance and medical treatment.

Democratising and Anticipating Everyday Futures Through Critical Design: A Review of Exemplars

This article explores design’s relation with the future by analysing a collection of exemplars from design fiction and speculative design for their potential to democratise and anticipate visions of future everyday life in design. Future visions – both implicit and explicit ones – have a realising power of their own. This is especially true for design, the products of which co-shape the lives of millions of users. Rather than calling for a “better” future vision however, this paper draws on research from the social sciences and futures studies to argue for the importance of diversifying and enriching visions of future everyday life within design. Critical design is well equipped to contribute to this objective because it questions the status quo and is relatable and actionable for designers. The paper reviews exemplars from critical design for their potential to democratise and anticipate future everyday life.
 To analyse their ways of engaging with future everyday life, the exemplars are positioned in the future cone model of probable, possible and preferred futures. Through this positioning, a distinction emerged between two forms of critical future engagement: alternative fictions and extrapolative fictions. Alternative fictions are explicitly positioned outside of generally expected futures, while extrapolative fictions are explicitly positioned within them. Both have their own strengths and limitations for democratising and anticipating future everyday life.
 Alternative fictions enrol actors as “future people” and create scenes to depict future contexts, but can also include deployments in present day contexts to explore alternative human-artefact relations. Alternative fictions tend to be accompanied by alternative design practices. Extrapolative fictions do not include deployments and rarely propose alternative design practices, but they can play an important role in highlighting the underexposed risks of mainstream design pursuits.
 Critical design can and should play a role in democratising and anticipating future everyday life. Alternative and extrapolative fictions can complement each other in this pursuit. Extrapolative fictions question the status quo from within and use the power of design to highlight underexposed aspects of expected futures. Alternative fictions question the status quo from without and use the power of design to creatively generate different objects that can be used to flesh out alternative ways of living and their related context. Further research is needed into how critical fictions are best integrated into mainstream design practices.

Small sphere limit of the quasi-local energy with anti de-Sitter space reference

In [13], a new quasi-local energy is introduced for spacetimes with a non-zero cosmological constant. In this article, we study the small sphere limit of this newly defined quasi-local energy for spacetimes with a negative cosmological constant. For such spacetimes, the anti de-Sitter space is used as the reference for the quasi-local energy. Given a point $p$ in a spacetime $N$, we consider a canonical family of surfaces approaching $p$ along its future null cone and evaluate the limit of the quasi-local energy. The optimal embedding equation which identifies the critical points of the quasi-local energy is solved in order to evaluate the limit. Using the optimal embedding, we show that the limit recovers the stress-energy tensor of the matter field at $p$. For vacuum spacetimes, the quasi-local energy vanishes to a higher order. In this case, the limit of the quasi-local energy is related to the Bel-Robinson tensor at $p$.

Rescue of M-cone Function in Aged Opn1mw-/- Mice, a Model for Late-Stage Blue Cone Monochromacy.

PurposePreviously we showed that AAV5-mediated expression of either human M- or L-opsin promoted regrowth of cone outer segments and rescued M-cone function in the treated M-opsin knockout (Opn1mw−/−) dorsal retina. In this study, we determined cone viability and window of treatability in aged Opn1mw−/− mice.MethodsCone viability was assessed with antibody against cone arrestin and peanut agglutinin (PNA) staining. The rate of cone degeneration in Opn1mw−/− mice was quantified by PNA staining. AAV5 vector expressing human L-opsin was injected subretinally into one eye of Opn1mw−/− mice at 1, 7, and 15 months old, while the contralateral eyes served as controls. M-cone–mediated retinal function was analyzed 2 and 13 months postinjection by full-field ERG. L-opsin transgene expression and cone outer segment structure were examined by immunohistochemistry.ResultsWe showed that dorsal M-opsin dominant cones exhibit outer segment degeneration at an early age in Opn1mw−/− mice, whereas ventral S-opsin dominant cones were normal. The remaining M-opsin dominant cones remained viable for at least 15 months, albeit having shortened or no outer segments. We also showed that AAV5-mediated expression of human L-opsin was still able to rescue function and outer segment structure in the remaining M-opsin dominant cones when treatment was initiated at 15 months of age.ConclusionsOur results showing that the remaining M-opsin dominant cones in aged Opn1mw−/− mice can still be rescued by gene therapy is helpful for establishing the window of treatability in future blue cone monochromacy clinical trials.

Causality re-established

Causality has never gained the status of a 'law' or 'principle' in physics. Some recent literature has even popularized the false idea that causality is a notion that should be banned from theory. Such misconception relies on an alleged universality of the reversibility of the laws of physics, based either on the determinism of classical theory, or on the multiverse interpretation of quantum theory, in both cases motivated by mere interpretational requirements for realism of the theory. Here, I will show that a properly defined unambiguous notion of causality is a theorem of quantum theory, which is also a falsifiable proposition of the theory. Such a notion of causality appeared in the literature within the framework of operational probabilistic theories. It is a genuinely theoretical notion, corresponding to establishing a definite partial order among events, in the same way as we do by using the future causal cone on Minkowski space. The notion of causality is logically completely independent of the misidentified concept of 'determinism', and, being a consequence of quantum theory, is ubiquitous in physics. In addition, as classical theory can be regarded as a restriction of quantum theory, causality holds also in the classical case, although the determinism of the theory trivializes it. I then conclude by arguing that causality naturally establishes an arrow of time. This implies that the scenario of the 'block Universe' and the connected 'past hypothesis' are incompatible with causality, and thus with quantum theory: they are both doomed to remain mere interpretations and, as such, are not falsifiable, similar to the hypothesis of 'super-determinism'.This article is part of a discussion meeting issue 'Foundations of quantum mechanics and their impact on contemporary society'.

Evaluating Small Sphere Limit of the Wang–Yau Quasi-Local Energy

In this article, we study the small sphere limit of the Wang-Yau quasi-local energy defined in [18,19]. Given a point $p$ in a spacetime $N$, we consider a canonical family of surfaces approaching $p$ along its future null cone and evaluate the limit of the Wang-Yau quasi-local energy. The evaluation relies on solving an "optimal embedding equation" whose solutions represent critical points of the quasi-local energy. For a spacetime with matter fields, the scenario is similar to that of the large sphere limit found in [7]. Namely, there is a natural solution which is a local minimum, and the limit of its quasi-local energy recovers the stress-energy tensor at $p$. For a vacuum spacetime, the quasi-local energy vanishes to higher order and the solution of the optimal embedding equation is more complicated. Nevertheless, we are able to show that there exists a solution which is a local minimum and that the limit of its quasi-local energy is related to the Bel-Robinson tensor. Together with earlier work [7], this completes the consistency verification of the Wang-Yau quasi-local energy with all classical limits.

A criterion of smoothness at infinity for an arithmetic quotient of the future tube

Let Γ be an arithmetic group of affine automorphisms of the n-dimensional future tube T. It is proved that the quotient space T/Γ is smooth at infinity if and only if the group Γ is generated by reflections and the fundamental polyhedral cone (“Weyl chamber”) of the group dΓ in the future cone is a simplicial cone (which is possible only for n ≤ 10). As a consequence of this result, a smoothness criterion for the Satake–Baily–Borel compactification of an arithmetic quotient of a symmetric domain of type IV is obtained.

Interception in differential pursuit/evasion games

A qualitative criterion for a pursuer to intercept a target in a class of differential games is obtained in terms of future cones: Topological cones that contain all attainable trajectories of target or interceptor originating from an initial position. An interception solution exists after some initial time iff the future cone of the target lies within the future cone of the interceptor. The solution may be regarded as a kind of Nash equilibrium. This result is applied to two examples: 1. The game of Two Cars: The future cone condition is shown to be equivalent to conditions for interception obtained by Cockayne. 2. Satellite warfare: The future cone for a spacecraft or direct-ascent antisatellite weapon (ASAT) maneuvering in a central gravitational field is obtained and is shown to equal that for a spacecraft which maneuvers solely by means of a single velocity change at the cone vertex. The latter result is illustrated with an analysis of the January 2007 interception of the FengYun-1C spacecraft.

Spacelike convex surfaces with prescribed curvature in (2 + 1)-Minkowski space

We prove existence and uniqueness of solutions to the Minkowski problem in any domain of dependence D in (2+1)-dimensional Minkowski space, provided D is contained in the future cone over a point. Namely, it is possible to find a smooth convex Cauchy surface with prescribed curvature function on the image of the Gauss map. This is related to solutions of the Monge–Ampère equation det⁡D2u(z)=(1/ψ(z))(1−|z|2)−2 on the unit disc, with the boundary condition u|∂D=φ, for ψ a smooth positive function and φ a bounded lower semicontinuous function.We then prove that a domain of dependence D contains a convex Cauchy surface with principal curvatures bounded from below by a positive constant if and only if the corresponding function φ is in the Zygmund class. Moreover in this case the surface of constant curvature K contained in D has bounded principal curvatures, for every K<0. In this way we get a full classification of isometric immersions of the hyperbolic plane in Minkowski space with bounded shape operator in terms of Zygmund functions of ∂D.Finally, we prove that every domain of dependence as in the hypothesis of the Minkowski problem is foliated by the surfaces of constant curvature K, as K varies in (−∞,0).

Current and future conifer seed production in the Alps: testing weather factors as cues behind masting

Temporal patterns of masting in conifer species are intriguing phenomena that have cascading effects on different trophic levels in ecosystems. Many studies suggest that meteorological cues (changes in temperature and precipitation) affect variation in seed-crop size over years. We monitored cone crops of six conifer species in the Italian Alps (1999–2013) and analysed which seasonal weather factors affected annual variation in cone production at forest community level. Larch, Norway spruce and silver fir showed masting while temporal patterns in Pinus sp. were less pronounced. We found limited support for the temperature difference model proposed by Kelly et al. Both seasonal (mainly spring and summer) temperatures and precipitations of 1 and 2 years prior to seed maturation affected cone-crop size, with no significant effect of previous year’s cone crop. Next, we estimated future forest cone production until 2100, applying climate projection (using RCP 8.5 scenario) to the weather model that best predicted variation in measured cone crops. We found no evidence of long-term changes in average cone production over the twenty-first century, despite increase in average temperature and decrease in precipitation. The amplitude of predicted annual fluctuations in cone production varies over time, depending on study area. The opposite signs of temperature effects 1 and 2 years prior to seed set show that temperature differences are indeed a relevant cue. Hence, predicted patterns of masting followed by 1 or more years of poor-medium cone production suggest a high degree of resilience of alpine conifer forests under global warming scenario.