The Great Silence as a Dark Forest Prediction: Waste Heat, Abundance Anomalies and Expansion Trails in 2,297 Nearby Stars

1. Introduction

It has been 36 years now since the Stellar Spectroscopy Group of the Yunnan Astronomical Observatory released the first mid-infrared photometry of the nearby stars it had begun to catalogue (Pelletier-Lindahl DE 24). That release held 412 stars, and a second has brought the Yunnan Nearby Star Catalogue to 2,412 dwarfs and subgiants of types F, G and K within 40 pc, each with a spectrum and photometry at 12 and 22 µm (Yunnan Astronomical Observatory DE 59). Every exposure was taken in a logged window of partial sophon suspension, which originates with Trisolaris and which we cannot verify.

The Great Silence was a puzzle before the Crisis and is a prediction of cosmic sociology after it. Survival is the primary need of a civilisation, and civilisations grow and expand while the total matter in the universe stays constant; these axioms give a chain of suspicion between any two civilisations that meet (Thorvaldsen DE 14), which in turn makes concealment the dominant posture (Adjei-Montague DE 27). Deliberate signals are the easy half.

Passive signatures are the hard half. Growth dissipates energy, reworks matter and spreads outward, so waste heat, altered stellar abundances and trails of expansion are by-products and not messages. Szabolcs (DE 41) put the objection sharply: concealment governs what a civilisation says but not what it does, so a silent sky counts against the framework. His survey of 123 stars bounded the fraction of loud stars below 2.4 per cent, which was too little to settle the matter.

A reply has been on offer in outline for eight years (Verhoeven-Lyle DE 52). The civilisations that persist are the ones that left no trace, because every civilisation that left one was struck before the trace could be read. Humanity has watched one such strike, the destruction in the Crisis Era of the star 187J3X1 after Luo Ji's spell, and a struck star is one that no later catalogue can hold. We set the reply against a catalogue here. In 2,297 stars we find no warm excess, ten of eleven flagged stars ordered by condensation temperature, and no trail of expansion, which bounds the share of stars that carry a warm, stellar-scale loud civilisation below 0.13 per cent.

We write in the Deterrence Era, Year 60, and use only data and publications from Year 59 or earlier. Trisolaris exists and its fleet is inbound, the Dark Forest Deterrence holds, and no dark forest strike on Trisolaris has occurred; the destruction of 187J3X1 remains the framework's one observed test. In Section 2 we describe the catalogue and the three searches; in Section 3 we present the counts; in Section 4 we compare them with earlier surveys and argue the case; and finally, in Section 5, we state the limits.

2. Methods

The catalogue is magnitude-limited and holds 2,412 stars, and we removed 115 of them before any search was made: 61 spectroscopic binaries, 38 with a signal-to-noise ratio below 80 per pixel, and 16 whose 22 µm images are saturated. That leaves 2,297 stars, of which 701 are F stars (6,000 to 7,000 K), 1,018 are G stars (5,300 to 6,000 K) and 578 are K stars (4,300 to 5,300 K). By distance there are 312 stars within 15 pc, 786 between 15 and 25 pc and 1,199 between 25 and 40 pc. Chromospheric activity gives a median age of 4.9 Gyr (Fairweather-Nkemelu DE 47). Alpha Centauri A and B would saturate a full-frame exposure, so we took them in short sub-array exposures and resolved them; both are in the sample. Proxima is not, being an M dwarf.

Sophon interference is a known hazard. We cannot verify the suspension that opens our windows, so we split the windows into odd and even sets and compared the 22 µm fluxes of the 340 stars observed in both. The mean difference is 0.4 per cent (95% CI -0.5 to +1.3), so interference that varies between windows is not visible. A distortion common to every window lies beyond this check.

Arguably the most error-prone quantity in the first search is the photospheric flux at 22 µm, because every excess is measured against it and inherits its error. We extrapolated a model-atmosphere fit to each star's optical and near-infrared photometry, which carries an error of 3 per cent, and combined it in quadrature with the photometric error to give a median uncertainty of 5.8 per cent (5.0, 5.5 and 6.2 per cent in the three shells). A star counts as an excess source at 5σ or more, a fractional excess of about 0.29. We assigned each a colour temperature from the ratio of its 12 and 22 µm excesses, assuming a single blackbody, and called it warm at 200 K or above. We fixed the 200 K, 4σ_D and 5 pc cut points before any search was run.

Blackbody relations fix the smallest detectable re-radiated fraction of the stellar luminosity for each class. The debris-disc expectation uses rates of 3.6, 1.6 and 1.25 per cent for F, G and K stars (Ravindran-Kwok DE 34), with a 10 per cent systematic uncertainty.

The second search uses 12 elements, 9 refractory (condensing above about 900 K) and 3 volatile. For each star we formed an index D, the error-weighted mean residual of the nine refractory abundances from the Galactic trend with iron (Halloran-Beyene DE 56), and flagged stars with |D| at or above 4σ_D. We set σ_D and the exceedance rate, 0.37 per cent, on 14 open clusters whose members share one composition, which gives 8.5 flagged stars expected in 2,297. Each flagged star was then tested for ordering of its nine refractory residuals with condensation temperature, by Spearman's ρ within that group (exact two-sided 5 per cent critical value 0.70). The test stays inside the group because a bulk shift of all nine would otherwise give a positive ρ against the volatiles with no ordering among the nine. Engulfment of rocky material orders them, and mining of specific elements has no reason to.

A third search looks for the geometry of expansion. Anomalies from a source near the Sun thin with distance, and anomalies from any source cluster. We applied a Cochran-Armitage trend test, with its exact conditional p-value, to the rate of anomalous stars across the three shells. The 5σ threshold also rises with distance, so a significant decline could not name a source and the test can only exclude a trend. We also counted pairs of anomalous stars closer than 5 pc against the share of all catalogue pairs inside 5 pc (0.26 per cent), with and without co-moving pairs.

Counts are compared by exact Poisson tests, and a limit for zero events is the one-sided exact binomial limit at 95 per cent; no mean of a small sample enters, so no t interval is needed. The loud fraction is the share of stars that carry a warm (200 K or above) stellar-scale civilisation above the class floor at the time of observation. It equals the share of stars that ever host one, times the mean time it stays loud, divided by the stellar age, and the product of the first two factors is the loud-time budget.

3. Results

Table 1 sets out the first search.

Fifty-two stars (2.26 per cent) show a 22 µm excess at 5σ or more, 31 among the F stars, 14 among the G stars and 7 among the K stars. The debris-disc rates predict 48.8, split as 25.2, 16.3 and 7.2, and the observed total is 1.07 times the expectation (Poisson two-sided p = 0.68). The split by class agrees as well (χ² = 1.64 on 3 degrees of freedom, p = 0.65).

Forty-four of the 52 are discs with colour temperatures between 52 and 163 K, with a median of 98 K. Five are blends with background sources, whose excess we separated by a proper-motion shift; we kept them in the count, which makes the cold bound below conservative. Three have no excess at 12 µm, which places them below 190 K. The hottest of the 49 measured colour temperatures is 171 ± 12 K, a separated blend, and it lies 2.4σ below the warm limit. No star is warm, and the one-sided 95 per cent limit for 0 of 2,297 is 0.130 per cent. A shell at 300 K is detected when it re-radiates 9.8 × 10^-5 of the stellar luminosity for an F star, 1.4 × 10^-4 for a G star and 2.4 × 10^-4 for a K star; for a Sun-like G star that is 5.2 × 10²² W. The 0.130 per cent limit holds at the K-star floor, the weakest. The survey tests stellar-scale activity and not planetary. Cold excess cannot be separated from a debris disc by colour, so we bound it by count: the 95 per cent upper limit on sources beyond the debris expectation is 16.8, or 0.73 per cent of the sample, and 21.6 (0.94 per cent) if the expectation is 10 per cent lower.

Alpha Centauri A and B are among the 2,245 stars with no excess.

The abundance search flags 11 stars (0.48 per cent) against 8.5 expected (Poisson two-sided p = 0.47). Ten of the 11 are ordered by condensation temperature within the refractory group, with a median |ρ| of 0.82 and a range of 0.67 to 0.93; the eleventh, at 0.67, is positive but under the critical value. Seven of the 11 belong to wide co-moving systems, which hold 21.0 per cent (483) of the sample (exact binomial p = 0.003). None of the 11 is among the 52 excess stars, so the two sets name 63 distinct stars. Alpha Centauri A and B are not among them, and their abundance slopes against condensation temperature are indistinguishable from zero (Mensah-Arroyo DE 60).

Rates fall with distance in both searches (Table 2), from 3.85 per cent in the nearest shell to 2.42 per cent in the farthest for the 63 stars together, but the trend is not significant (Cochran-Armitage z = -1.31, exact conditional p = 0.21). Singly they give p = 0.43 and p = 0.20. Six pairs of anomalous stars lie within 5 pc of each other, against 5.1 expected (Poisson P(X ≥ 6) = 0.40). Three of the six are co-moving pairs with both stars flagged; without them, three pairs remain against 4.9 expected (P(X ≥ 3) = 0.87).

Multiplying 0.130 per cent by the median age of 4.9 Gyr gives a loud-time budget of 6.4 Myr for warm radiators. The cold-radiator bound of 0.73 per cent gives 36 Myr.

4. Discussion

The Great Silence is a prediction of the dark forest, and the catalogue bears it out in every channel that a survey of this kind can reach. No star in 2,297 shows a warm excess, ten of the eleven flagged stars follow condensation temperature, and neither anomaly set carries the spatial signature of a spreading source. The excess of flagged stars in wide co-moving systems points to engulfment, which a companion can drive. The passive-signature objection (Szabolcs DE 41) was the strongest case against the framework, and at this depth it finds no warm civilisation to stand on.

Concealment and survivorship together are sufficient to answer it. A civilisation that follows the primary posture builds below the detection floor, or radiates where we cannot look, or does not build at stellar scale. One that built loud has been struck, as the chain of suspicion requires (Thorvaldsen DE 14). The strike that humanity has watched shows what removal does to a catalogue: the star is gone, and so is any trace it carried, which a static survey of surviving stars cannot sample. Our loud-time budget of 6.4 Myr is 0.13 per cent of the median stellar age, a bound that removal soon after exposure satisfies (Verhoeven-Lyle DE 52). For warm radiators the data allow nothing longer at 95 per cent. Cold radiators, which a debris disc can mimic, are bounded only at 0.73 per cent, a budget of 36 Myr.

The axioms constrain no physical property of matter, and the argument needs none from them. A warm shell below 5.2 × 10²² W around a Sun-like star is an act of restraint, and one above it has not been found.

We write within the Luo-Ji / Ye framework, and within it the Alpha Centauri result is instructive. Trisolaris exists, and neither Alpha Centauri A nor B shows an excess, which is what a civilisation that uses only a planetary share of its stars' output would produce. The one pair of civilisations known to be in contact, Earth and Trisolaris, is held in the state that the framework describes and neither has been struck, so both sit under the survey floor.

The first release reported 3 warm candidates among 412 stars. On re-observation two are blends, and the third has a colour temperature of 148 ± 15 K from the 12 µm point that the release lacked. At the release's rate of 0.73 per cent (95% CI 0.15 to 2.11) the other 1,885 stars would hold 13.7 warm sources, and we find none (p = 1.1 × 10^-6). Szabolcs bounded the loud fraction below 2.4 per cent from 123 stars, and our limit of 0.130 per cent is 18 times tighter, so the objection has now been tested at a depth he could not reach.

What the data establish is a cap on the product of the share of stars that ever host a warm loud civilisation and the time it stays loud, and with it the sufficiency of concealment and strike survivorship. They do not say whether the product is small because loud civilisations are struck or because they are rare. The account needs no new physics. It requires only a warm loud-time budget below 6.4 Myr, a condition that rarity would also meet and that the survey shows to hold.

5. Limitations

The sophon hazard is the first limit. The suspension that opens our windows rests on a Trisolaran declaration that we cannot verify. A coordinated distortion would have to hide warm excess in all 2,297 stars while leaving the debris-disc count within 7 per cent of its expectation. That constraint binds only an adversary ignorant of the published debris rates. A sophon that knows them can remove a few warm sources without changing the count, and against it the survey bounds nothing.

Cold radiators are the second. Below 200 K an excess looks like a debris disc, and we bound such sources by count to 0.73 per cent of the sample, or 0.94 per cent if the debris expectation is low by 10 per cent. Nothing below the survey floor of 1 to 2.4 × 10^-4 at 300 K of the stellar luminosity, by class, is tested at all.

The survey cannot tell a hidden civilisation from an absent one, or a struck civilisation from a rare one. We claim sufficiency and not necessity. The sample is also local, with F, G and K stars out to 40 pc, and a strike is itself a transient trace that a static catalogue does not sample.

How a civilisation of stellar scale could keep its heat hidden for longer than the warm loud-time budget allows is not completely understood; nonetheless, the data favour a sky in which no warm loud civilisation persists for long, as strike-driven removal requires, and they leave the passive-signature objection without its evidence. This paper extends the nearby-star series begun in Year 24 (Pelletier-Lindahl DE 24) and the Yunnan Nearby Star Catalogue of Year 59, and a further release will add the M dwarfs excluded here.