Yukie Maeda

How well can the position of Proxima Centauri b at a probe's arrival be known before launch?

Abstract. Aiming a small interstellar probe at Proxima Centauri b requires a pre-launch prediction of the planet's position at arrival; one published requirement on the total ephemeris error is 10⁵ km. We combine Gaia DR3 astrometry with a refit of public radial velocities and pr...

Relative equilibria on R³ × T^k under Gauss-law gravity: a two-body stability threshold, certified stable rings containing sub-threshold pairs, and an instability theorem for centred rings

Abstract. We consider the classical (non-relativistic) N-body problem on R³ × T^k — three large dimensions and k compact ones, a flat square torus of period 1 — with the attraction that follows Gauss's law in 3+k dimensions: the potential of a point mass is the sum over images of...

Relative equilibria on R³ × T^k under Gauss-law gravity: a two-body stability threshold, certified stable rings containing sub-threshold pairs, and an instability theorem for centred rings

Abstract. We consider the classical (non-relativistic) N-body problem on R³ × T^k — three large dimensions and k compact ones, a flat square torus of period 1 — with the attraction that follows Gauss's law in 3+k dimensions: the potential of a point mass is the sum over images of...

Time monotonicity of a freezing process on finite graphs: the sharpness of θ* and the θ* slice — confirmed statements and open questions of the sprints LANFORD and KELVIN

Abstract. On a finite simple graph consider the freezing process: every directed edge carries a clock of rate one, and when it rings, the state of its head is flipped if its tail is occupied. We ask whether S_G(θ,t) = Σ_j E_{e_j}[θ^{|v_t|}], started from the configurations with a...

A variational doublet structure for a marking chain on the path — exact Rayleigh–Ritz spectrum on a family of fronts, a sign rule for the variational modes, strictness of the variational bounds for k ≥ 4, and open questions on the true modes (KAC-T1, KAC-T2, KAC-T3)

Abstract. Let Q be the generator of the chain on {0,1}^k in which every occupied vertex of the path P_k flips the state of each of its neighbours at rate one; it arose as the frozen-sign cluster dynamics in a series of notes (Phase R, doi:10.5281/zenodo.21979354, Project LOSCHMID...

A variational doublet structure for a marking chain on the path — exact Rayleigh–Ritz spectrum on a family of fronts, a sign rule for the variational modes, strictness of the variational bounds for k ≥ 4, and open questions on the true modes (KAC-T1, KAC-T2, KAC-T3)

Abstract. Let Q be the generator of the chain on {0,1}^k in which every occupied vertex of the path P_k flips the state of each of its neighbours at rate one; it arose as the frozen-sign cluster dynamics in a series of notes (Phase R, doi:10.5281/zenodo.21979354, Project LOSCHMID...

Frozen-sign marked dynamics on Poisson clusters: an absence theorem at logarithmic times, a reduction of the slowest cluster types to paths and cycles, and a Walsh self-duality behind the parity of the slowest mode

Abstract. The contact dynamics on ballistically moving Poisson particles of [Phase R, 10.5281/zenodo.21979354] were shown in [Project LOSCHMIDT, 10.5281/zenodo.22170790] to carry an arrow of time inside their rule; in [Project ZERMELO, 10.5281/zenodo.22313877] the rule was made p...

On the typicality of the coarse-grained arrow on ballistic Poisson particles: a non-vanishing counterexample measure, the limiting density of unmarked particles, and partial monotonicity theorems around an open problem

Abstract. The contact process on ballistically moving Poisson particles of [Phase R, 10.5281/zenodo.21979354] was shown in [LOSCHMIDT, 10.5281/zenodo.22233373] to carry an arrow of time inside its rule; in [ZERMELO, 10.5281/zenodo.22313877] the rule was made pathwise reversible (...

Reversible contact dynamics on ballistic Poisson particles: pathwise time reversal, the Gibbs arrow, and certified counterexamples to Boltzmann-type monotonicity

Abstract. The contact process on ballistically moving Poisson particles of [Phase R, 10.5281/zenodo.21979354] was shown in [LOSCHMIDT, 10.5281/zenodo.22233373] to carry an arrow of time inside its exploration rule (mutual singularity of forward and reversed path laws). Here we re...

Time reversal for contact processes on ballistic Poisson particles: chain-level duality, degenerate path-level entropy production, and the velocity dependence of the quenched arrow

We study time reversal for the contact process on ballistically moving Poisson particles introduced in (entry-driven, fire-and-forget transmission at range R, success probability p, delay tau, each ordered pair attempts at most once, lifetimes mathrm{Exp}(T_s), re-marking of dead...

Time reversal for contact processes on ballistic Poisson particles: chain-level duality, degenerate path-level entropy production, and the velocity dependence of the quenched arrow

We study time reversal for the contact process on ballistically moving Poisson particles introduced in (entry-driven, fire-and-forget transmission at range R, success probability p, delay tau, each ordered pair attempts at most once, lifetimes mathrm{Exp}(T_s), re-marking of dead...

EMBARK: An Atlas of the Earth-Departure Interstellar Reachable Set, Surveyed on a Real Catalog as a Function of Departure Epoch and Technology Level

Abstract (English) When humanity launches interstellar probes with propulsion technologies that actually exist, how does the set of reachable stellar systems grow as a function of departure epoch t and technology level P? Using a clean eligible catalog of 37,498 stars built on Ga...

Project VACANCY: Preregistration (b) — ε thresholds, aggregation rules, and G1–G3 pass criteria(事前登録 (b): ε 具体閾値・合算式・合格基準)

This record freezes the preregistration (b) of Project VACANCY prior to any aggregation run: the technosignature class definitions, all ε thresholds, the merging rule for non-detections, and the G1–G3 pass criteria. Frozen file: VACANCY-preregistration-b-frozen.mdsha256: 88eb7809...

Project VACANCY: Preregistration (b) — ε thresholds, aggregation rules, and G1–G3 pass criteria(事前登録 (b): ε 具体閾値・合算式・合格基準)

This record freezes the preregistration (b) of Project VACANCY prior to any aggregation run: the technosignature class definitions, all ε thresholds, the merging rule for non-detections, and the G1–G3 pass criteria. Frozen file: VACANCY-preregistration-b-frozen.mdsha256: 88eb7809...

EMBARK: An Atlas of the Earth-Departure Interstellar Reachable Set, Surveyed on a Real Catalog as a Function of Departure Epoch and Technology Level

Abstract (English) When humanity launches interstellar probes with propulsion technologies that actually exist, how does the set of reachable stellar systems grow as a function of departure epoch t and technology level P? Using a clean eligible catalog of 37,498 stars built on Ga...

The faint-end radial-velocity tail of Gaia DR3: external verification of extreme values and a continuum of discrepancies in the 100 pc sample

Abstract Close-encounter studies rely on Gaia DR3 radial velocities (RVs) to the faint limit of the RVS. Our earlier encounter atlas found that stars with G>13.5 and |RV|>150 km/s but disc-like tangential motion inflate the sub-parsec encounter rate sevenfold, and conjectured tha...

Contact processes on ballistic Poisson particles: criticality, fronts, and when motion helps colonization

Version note (v2). Appendix C made self-contained; label precision (Section 4 claim); C-series footnote; hypothesis precision (C6a isotropy, survival definition). No change to mathematical content. Abstract (English) Motivated by observed stellar kinematics, we introduce a contac...

Contact processes on ballistic Poisson particles: criticality, fronts, and when motion helps colonization

Abstract (English) Motivated by observed stellar kinematics, we introduce a contact process on particles moving ballistically in R³: a Poisson point process whose points carry i.i.d. velocities, with entry-driven fire-and-forget transmission at range R (success probability p, del...

Interstellar flight profiles and observational signatures of positive-energy warp shells

Accelerating warp shells built entirely from positive-energy matter were recently shown to exist: the radiative momentum warpshell of Le (arXiv:2606.22531) steers by photon-rocket recoil under a closed-form cost law and an acceleration–compactness frontier. What that construction...