Thermodynamics - Heliomance/Uncharted-Horizons GitHub Wiki

_{Focus Areas · Design document §3}

Available from: MC08 (Steam Engine) or MC07 (Hero's Aeolipile)

19 breakthroughs — CORE 3 · STANDARD 16 — Classical – Space

Builds on: Observation (2) · Metallurgy (3) · Mathematics (2) · Philosophy and the Arts (1) · Mechanics (6) · Chemistry (3) · Electricity (1) · Quintessic Physics (1)

Leads into: Medicine (1) · Chemistry (3) · Electricity (2) · Nuclear Physics (1) · Relativity & Cosmology (1) · Rocketry (1) · Aeronautics (2) · Energy Systems (11)

_{The numbers count prerequisite links between this focus and the other. How to read the tables.}

flowchart LR
  n_TH01["TH01 Laws of Thermodynamics"]:::CORE
  n_TH02["TH02 Refrigeration"]:::STANDARD
  n_TH18["TH18 Deep Cryogenics"]:::STANDARD
  n_TH21["TH21 Atmospheric Heat Management"]:::STANDARD
  n_TH22["TH22 Geoengineering Programme"]:::STANDARD
  n_TH03["TH03 Turbine Design"]:::CORE
  n_TH15["TH15 Waste-Heat Recovery"]:::STANDARD
  n_TH16["TH16 Heat Pump Networks"]:::STANDARD
  n_TH17["TH17 Supercritical Power Cycles"]:::STANDARD
  n_TH19["TH19 Permafrost Engineering"]:::STANDARD
  n_TH05["TH05 Carnot Efficiency"]:::STANDARD
  n_TH08["TH08 Stirling Engine Mastery"]:::STANDARD
  n_TH10["TH10 Mechanical Equivalent of Heat"]:::CORE
  n_TH20["TH20 Boundary Ring / Cycle-Limit Ring"]:::STANDARD
  n_TH09["TH09 Caloric Theory"]:::STANDARD
  n_TH11["TH11 Caloric Storage"]:::STANDARD
  n_TH12["TH12 Caloric Projection"]:::STANDARD
  n_TH13["TH13 The Weight of the Air"]:::STANDARD
  n_TH14["TH14 Atmospheric Engine"]:::STANDARD
  n_TH01 --> n_TH02
  n_TH01 --> n_TH03
  n_TH03 --> n_TH15
  n_TH05 --> n_TH15
  n_TH15 --> n_TH16
  n_TH15 --> n_TH17
  n_TH15 --> n_TH18
  n_TH02 --> n_TH18
  n_TH15 --> n_TH19
  n_TH17 --> n_TH21
  n_TH18 --> n_TH21
  n_TH21 --> n_TH22
  n_TH16 --> n_TH22
  n_TH01 --> n_TH05
  n_TH01 --> n_TH08
  n_TH01 -.-> n_TH10
  n_TH09 -.-> n_TH10
  n_TH09 --> n_TH11
  n_TH11 --> n_TH12
  n_TH13 --> n_TH14
  classDef CORE fill:#dbeafe,stroke:#1d4ed8,color:#0b1b3b
  classDef STANDARD fill:#f1f5f9,stroke:#64748b,color:#0f172a
  classDef UNCOMMON fill:#dcfce7,stroke:#15803d,color:#052e16
  classDef RARE fill:#fef3c7,stroke:#b45309,color:#3b2005
  classDef UNIQUE fill:#fae8ff,stroke:#a21caf,color:#3b0a3f

_{Prerequisites within this focus. Box colour is the tier (blue CORE, grey STANDARD, green UNCOMMON, amber RARE, purple UNIQUE); dotted arrows are alternatives (“or”); a line can pass behind another box, so follow it from its start. 11 of these 19 breakthroughs also need breakthroughs from other foci, which the overview above lists.}

• Tier: CORE · Era: Early Modern
• Prerequisites: MC08 + PH04 (Scientific Method)
• Unlocks: ⟨[+1 Production] from all [Steam Works] buildings⟩ — the engine understood; grants THERMO_THEORY if the kinetic account validates. Frontier Question FQ12: resolved by TH10. In Caloric worlds (~30%) TH01's account dead-ends and TH09/TH11 serve instead.
• Notes: The kinetic theory of heat — correct in most universes.
• Leads to: TH02 Refrigeration, TH03 Turbine Design, TH05 Carnot Efficiency, TH08 Stirling Engine Mastery, TH10 Mechanical Equivalent of Heat, CH13 Rocket Propellant, CH26 Closed-Loop Calorimetry, NP04 Nuclear Fusion, RC04 Black Hole Thermodynamics, RK02 Liquid Fuel Rocket, ES09 Geothermal Power

• Tier: STANDARD · Era: Modern
• Prerequisites: TH01 + CH04 (Distillation — acids) + CH06 (Periodic Table)
• Unlocks: Stadium; ⟨[15]% Food is carried over after population increases [in all cities]⟩ — nothing spoils. ⟨[+1 Gold] from all [Factory] buildings⟩ — industrial gases, liquefied and sold: Linde built the refrigerator and then liquefied air. Liquid gases: rocket oxidiser (RK02), the superconductor path (EL11), cold storage (MD13) (Cryogenics, merged here in v3.103).
• Leads to: MD13 Cryogenic Preservation, TH18 Deep Cryogenics, CH27 Formless Reserve, EL11 Superconductivity

• Tier: CORE · Era: Modern
• Prerequisites: TH01 + MC03 (Gearing) + ME12 (Bessemer)
• Unlocks: ⟨[+15]% Production when constructing [Water] units [in all cities]⟩ — turbine-driven ships. Prerequisite for every power plant. ⟨[+1 Happiness] in cities on [Snow] tiles⟩ (district heating) — turbines and heat exchangers, the steam plant's two halves; prerequisite for reactors (Heat Exchanger, merged here in v3.103).
• Leads to: TH15 Waste-Heat Recovery, EL06 Electric Generator, AE04 Jet Engine, ES03 Coal Power Plant, ES03-W Biomass Power Plant, ES05 Oil Power Plant, ES05-W Alcohol/Biogas Power Plant, ES06 Nuclear Fission Plant, ES08 Fusion Reactor, ES10 Tidal Power, ES15 Quintessic Power Plant, ES16 Caloric Engine Plant

• Tier: STANDARD · Era: Space
• Prerequisites: QM-E05 + EL11 — cost ×4
• Unlocks: ⟨[+15]% [Science] <in cities with a [Deep Matter Lab]>⟩ — the converter ring of elemental worlds, driven by bound-energy release: NP15's mirror.
• Notes: W18 — Pool; elemental Tachyonic engineering (elemental worlds only).

• Tier: STANDARD · Era: Space
• Prerequisites: TH03 + TH05 — cost ×2.5
• Unlocks: ⟨[+1 Production] from all [Factory] buildings⟩.
• Notes: W18 — Entry: opens the pool.
• Leads to: TH16 Heat Pump Networks, TH17 Supercritical Power Cycles, TH18 Deep Cryogenics, TH19 Permafrost Engineering

• Tier: STANDARD · Era: Space
• Prerequisites: TH15 — cost ×2.5
• Unlocks: ⟨[+1 Production] per [4] population [in all cities]⟩.
• Notes: W18 — Pool.
• Leads to: TH22 Geoengineering Programme

• Tier: STANDARD · Era: Space
• Prerequisites: TH15 — cost ×2.5
• Unlocks: ⟨[+1 Production] from all [Power Plant] buildings⟩.
• Notes: W18 — Pool.
• Leads to: TH21 Atmospheric Heat Management

• Tier: STANDARD · Era: Space
• Prerequisites: TH15 + TH02 — cost ×2.5
• Unlocks: ⟨[+15]% Food is carried over after population increases⟩, stacking with TH02's.
• Notes: W18 — Pool.
• Leads to: TH21 Atmospheric Heat Management

• Tier: STANDARD · Era: Space
• Prerequisites: TH15 + tundra tiles in territory — cost ×2.5
• Unlocks: A worker-built improvement that, ⟨<upon building>⟩ it, will ⟨Turn this tile into a [Plains] tile⟩ on tundra (to be tested in play). A civilisation without tundra never becomes eligible, so never wastes a discovery on it.
• Notes: W18 — Pool; the one cold-land row.

• Tier: STANDARD · Era: Space
• Prerequisites: TH17 + TH18 — cost ×2.5
• Unlocks: ⟨[+10]% [Food] [in all cities]⟩.
• Notes: W18 — First step of capstone A.
• Leads to: TH22 Geoengineering Programme

• Tier: STANDARD · Era: Space
• Prerequisites: TH21 + TH16 — cost ×4
• Unlocks: ⟨[+15]% [Food] [in all cities]⟩ — a stabilised climate and reliable harvests (if the fork gains a disaster mechanic, reducing disasters is its natural effect).
• Notes: W18 — Capstone A.

• Tier: STANDARD · Era: Early Modern
• Prerequisites: TH01 + MA05 (Calculus)
• Unlocks: ⟨[+1 Production] from every [Engineer]⟩ — the engineer who knows the limit gets closest to it. Knowing the limit gets you closest to it.
• Leads to: TH15 Waste-Heat Recovery, AE08 Scramjet

• Tier: STANDARD · Era: Early Modern
• Prerequisites: TH01 + MC08
• Unlocks: Stirling Worksⁿ [a grid plant: ⟨Power Plant⟩ (tag); 60/0; requires a Factory in this city; +1 Production; burns anything, needs no resource; ⟨Remove [{Power Plant} {non-[Stirling Works]}] [in this city]⟩] — the earliest and weakest plant, fuel-free, holding a city's plant slot until something better is worth the swap. Strategically vital in FOSSIL_FUELS_ABSENT worlds. Also discoverable through Mechanics or Energy Systems. Competing Solution (§1.2): the alternative to Internal Combustion Engine (MC09), detour margin ×1.5 while Internal Combustion Engine exists in this world; if Internal Combustion Engine is discovered first this is never developed, and if it arrives later this persists — it burns anything.
• Notes: Less power but universal fuel compatibility.

• Tier: STANDARD · Era: Early Modern
• Prerequisites: MC08 + O06 (Natural Philosophy)
• Unlocks: ⟨[+1 Production] from all [Steam Works] buildings⟩ (the engine runs whatever heat is — the bonus Laws of Thermodynamics gives elsewhere); +10% Insight to energy research while held; grants THERMO_THEORY if validated. FQ12: resolved by TH10.
• Notes: Heat as a weightless fluid — wrong in our world, right in others.
• Leads to: TH10 Mechanical Equivalent of Heat, TH11 Caloric Storage

• Tier: CORE · Era: Early Modern
• Prerequisites: (TH01 or TH09) + MA03 (Basic Algebra)
• Unlocks: Joule Laboratoryⁿ [national wonder; 200/0; +2 Science; on completion ⟨Triggers a [Mechanical Equivalent of Heat] event⟩ and Reveals the heat this world has: Turbine Design (TH03) in Kinetic worlds (~70%), the Caloric Reservoir (TH11) in Caloric worlds (~30%)]. The decisive experiment for FQ12 — Joule's paddle-wheel and Rumford's cannon: does friction make limitless heat, or is heat a conserved fluid?
• Notes: Sometimes the water warms without limit; sometimes the caloric is merely moved.

• Tier: STANDARD · Era: Modern
• Prerequisites: TH09 (validated) + CH04 (Distillation — acids)
• Unlocks: Caloricⁿ — a new stockpiled resource (heat-fluid; Stockpiled, never placed on the map). Caloric Reservoirⁿ [250/1; ⟨Provides [4] [Caloric]⟩; ⟨Remove [Solar Reservoir] [in this city]⟩; ⟨Remove [Heat Exchange] [in this city]⟩ — 4 Caloric a turn and nothing else: a bank, not a factory]; Solar Reservoirⁿ [250/1; ⟨Provides [6] [Caloric]⟩; ⟨Must be on [Desert]⟩; ⟨Caloric Reservoir⟩ (tag); ⟨Remove [{Caloric Reservoir} {non-[Solar Reservoir]}] [in this city]⟩; ⟨Remove [Heat Exchange] [in this city]⟩ — the hot lands bank 6]. (A separate Desert-sited building because no city-terrain conditional exists for Provides; its tag makes it match every [Caloric Reservoir] filter, since Building.matchesFilter matches any exact unique a building has. Either reservoir retires the other, so a desert city banks 6, never 6 and 4.) Banking Heatⁿ — a perpetual process: ⟨Enables conversion of city production to [Caloric]⟩ at 2 Production → 1 Caloric, ⟨Only available <in cities with a [Caloric Reservoir]>⟩ — which, via its tag, admits the Solar Reservoir too (fork extension, as CH20). Heat Exchangeⁿ [⟨Costs [40] [Caloric]⟩; +2 Production; +2 Happiness; ⟨[+2 Food, +1 Happiness] in cities on [Snow] tiles⟩; ⟨[+1 Food, +1 Happiness] in cities on [Tundra] tiles⟩ — heat is worth most where there is least of it; ⟨Remove [Caloric Reservoir] [in this city]⟩ — which, via the tag, retires a Solar Reservoir too: a city banks or draws, and can change its mind]. Heat banked in the desert warms the frozen frontier: heat is a real, conserved, storable substance, and here it is also a currency. Only in Caloric worlds. Grants THERMO_THEORY.
• Notes: Only in Caloric worlds (FQ12). Bottle the fire, sell it by the barrel.
• Leads to: TH12 Caloric Projection, ES16 Caloric Engine Plant

• Tier: STANDARD · Era: Modern
• Prerequisites: TH11 + WA-any (any military breakthrough)
• Unlocks: Caloric Lanceⁿ [unit, Siege; cost 150 + ⟨Costs [40] [Caloric]⟩; mv 2; str 25; ranged str 40; range 2; ⟨[+50]% Strength <vs cities>⟩ — armies fielded from banked heat]; Thermal Wardⁿ [⟨Costs [30] [Caloric]⟩; cityStrength +5]. Heat as a munition — no powder, no shot, and every shot drains the treasury of warmth.
• Notes: The caloric world's answer to artillery — heat as a munition.

• Tier: STANDARD · Era: Classical
• Prerequisites: MC07 (Hero's Aeolipile) + O06 (Natural Philosophy)
• Unlocks: Condensing Pumpⁿ [50/1; +1 Happiness; ⟨[+10]% growth [in this city]⟩] — steam condensed in a closed vessel leaves a vacuum, and the air pushes water in behind it: water raised a few metres from any well or stream, for the city's houses and fountains. Every Thermodynamics breakthrough costs ×0.9 for a civilisation that has this (a multiplier, §1.2) — the field it has been exploring longest. Follow-up of the Early Steam chain (§1.2).
• Notes: Hero's Pneumatica opens, after Strato, by arguing that small vacua exist — the idea Aristotle's horror vacui denied, and the one our own history had to wait for Torricelli and Guericke to supply. This is Savery's pump (1698) without the pressure stage that burst its boilers. Savery sold it as The Miner's Friend, but its lift was too short for mines; it found its work in houses and gardens.
• Leads to: TH14 Atmospheric Engine

• Tier: STANDARD · Era: Medieval
• Prerequisites: TH13 + (ME02 or ME05 — bronze or cast iron for the cylinder) + MC03 (Gearing — the lever and the beam)
• Unlocks: Engine Houseⁿ [175/1; requires a Workshop in this city; ⟨Consumes [1] [Coal]⟩; ⟨[+1 Production] from [Mine] tiles [in this city]⟩; ⟨[+2 Food, +1 Production] [in this city] <in cities without a [Water Mill]>⟩; ⟨Unavailable <after discovering [Steam Engine]>⟩; ⟨[+100]% Production when constructing [Steam Works] buildings [in this city]⟩] — a beam engine that drains deep workings and, where no river turns a wheel, pumps water back over one: a mill away from the river. Stationary, reciprocating and ruinous on fuel, so it burns Coal where Coal is cheap — from a pit, or from a Charcoal Kiln. Makes the Steam Engine (MC08) cost ×0.5 (a multiplier, §1.2). Competing Solution (§1.2): the alternative to Steam Engine (MC08), detour margin ×1.5 while Steam Engine exists in this world; if Steam Engine is discovered first this is never developed, and if it arrives later this is superseded — no new Engine Houses, but existing ones keep pumping until converted: a Steam Works in their city goes up twice as fast, reusing the house, beam and pit, and retires them. Converting frees the Coal and gains the Steam Works' power, but gives up the mine and mill yields, so a dry mining town may keep its old engine for a while. Follow-up of the Early Steam chain (§1.2).
• Notes: Newcomen's engine (1712) never ran above about one atmosphere: the air did the work, and a piston sealed with leather and a layer of water hid a poor bore, so it needed no machining. It paid only at the pithead, burning coal no one could sell, and in the mid-1700s engines pumped water back over wheels to run mills. Newcomen engines kept working for decades after Watt's arrived, and many were refitted with Watt's condenser rather than replaced.