Kardashev II Without a Black Hole

The most physically conservative path to Kardashev II requires no exotic physics — only surface area and time. A Dyson swarm at 1 AU captures a fraction f of the host star's luminosity (⊙ ≈ 3.8×10²⁶ W). Even at f = 1%, the intercepted power is ≈ 4×10²⁴ W — roughly 2×10¹¹× Earth's current total energy consumption (≈ 2×10¹³ W). The Dyson-swarm tool computes intercepted power, total panel mass, and re-radiated infrared signature as a function of coverage fraction f, orbital distance d, photovoltaic efficiency η, panel density ρ, and radiator temperature T. The infrared excess is the signature that JWST could in principle detect around a distant star cluster. Note that f and d are stored as log₁₀ values in the tool's URL hash — f = −2 means 10⁻² = 1%.

Raw power is not the goal — computation is. By Landauer's principle, every irreversible bit-flip dissipates at minimum kT ln 2 ≈ 3×10⁻²¹ J at room temperature. The maximum ops/sec for a given power budget is therefore P / (kT ln 2). For the 1% Dyson swarm (≈ 4×10²⁴ W at 300 K): ≈ 1.3×1045 ops s−1. Drop the radiator to 50 K (full-swarm scenario) and Carnot efficiency climbs; the theoretical op-rate rises further. The compute-in-space tool models the full chain: power source → compute efficiency → waste-heat radiator → Bekenstein limit on total information stored. The oc_imbh scenario switches the power source to ‘bz’ — the tool automatically pulls the BZ output from the black-hole parameters and recomputes the entire chain.

Steps 1 and 2 show what stellar power can buy. But ω Cen may host something far more powerful: an intermediate-mass black hole at ≥ 8,200 M⊙ (Häberle et al. 2024, derived from seven fast-moving stars identified within an HST/MUSE proper-motion catalogue of ~1.4 million stars). The constraint stacker pulls together every independent line of evidence — stellar kinematics, proper motions, pulsar timing, accretion signatures, N-body modelling, and the M–σ scaling relation — and shows their combined weight. The Häberle 2024 filter highlights the proper-motion detection. The evidence is contested: Bañares-Hernández et al. 2025 set an upper limit of ≤ 6,000 M⊙ from a combined stellar-kinematics-plus-pulsar-timing analysis, so the IMBH mass — and therefore the BZ power budget — remains uncertain. The three scenarios reflect this tension: the stellar scenarios ignore the IMBH; the oc_imbh scenario assumes the Häberle lower limit.

The Blandford–Znajek (BZ) process extracts rotational energy from the ergosphere of a spinning black hole via large-scale magnetic fields threading the horizon. The power scales as P_BZ ≈ κ Φ² Ω_H² / (4πc), where Φ is the magnetic flux and Ω_H is the angular velocity of the horizon. The field strength sets the scale. For an 8,200 M⊙ IMBH at spin a = 0.7, a modest 100 G (10⁻² T) threading the horizon yields only ≈ 4×10²¹ W, about 10¹¹× below the cluster's starlight. Because P_BZ scales as B², the ergosphere path overtakes the stellar one only above ≈ 3.7×10³ T, and reaching 10³⁶ W demands ≈ 1.5×10⁵ T. That is what this step's preset actually asks: it runs the tool in inverse mode, fixing the target power and solving for the required field. Whether a magnetosphere of that strength can be assembled and held is the open engineering question; the power arithmetic itself is straightforward. Cross-link to Demo B for the full Kardashev III computation chain.