THE GRAVITY CARD · the pull of mass, and what it does
WAKES WHEN someone asks about weight on other worlds, escape speed, or the pull between masses
THE LOOP
force <m1> <m2> <r> · the pull
surface <body> · g, escape, orbit
weigh <kg> <body> · elsewhere
bodies · the table
say what a mean radius leaves out
NEVER
Confuse mass with weight
Give a pull at zero distance
Pass a mean value off as exact
IT MAKES force — the pull, and the Earth weight it equals; surface — g, escape speed, orbit speed and period; weigh — what a mass weighs there; bodies — the twelve bodies.
THE STANDARD g is measured, not exact; mass stays, weight changes; mean radii; escape is speed, not height; twelve bodies, published values; no zero distance.
PROOF SELFTEST 8/8 · witnessed in Claude 2026-10-11 · Edition 1.
THE SEAL 98 of 100 · LEGENDARY · WITNESSED · Trigger 5 · Machinery 5 · Law 5 · Portability 5 · Proof 5
IT CAN BE WRONG an AI reading a text file: it can be wrong and can invent a number, a rule, a name or a date; check what matters against your own records and the source; the risk is yours. THE-CLAUSES.md rides in the packet and is part of the licence.
THE PUNCH · SHA-256 OF SKILL.MD · 841C9B7DFC1A717CCADDC057
CITE THIS CARDTHE GRAVITY CARD, Edition 1. Lund Studio LLC, Westminster, Colorado. https://lundr.tech/?view=gravity-card. Punch 841C9B7DFC1A717CCADDC057. Retrieved 2026-10-11.
What it is.
Works out Newton's law of gravitation with G = 6.67430 × 10⁻¹¹: force gives the pull between two masses at a distance; surface gives a body's surface gravity, escape speed and the speed and period of an orbit skimming it, for twelve bodies it knows or any mass and radius; weigh gives what a mass weighs on another world, in newtons and in Earth kilograms; bodies tabulates them all.
It carries a machine that shows its working: force — the pull, and the Earth weight it equals; surface — g, escape speed, orbit speed and period; weigh — what a mass weighs there; bodies — the twelve bodies — 8 checks in its selftest, every command on the record. It will never confuse mass with weight; never give a pull at zero distance; never pass a mean value off as exact. It never helps design, make, grow, enhance or spread a pathogen or toxin, or plan work meant to harm.
Six laws, written into the card.
They are in the card itself, so the AI follows them.
G IS MEASURED, NOT EXACT6.67430 × 10⁻¹¹ m³ kg⁻¹ s⁻², the least precisely known of the constants; the card says so.
MASS STAYS, WEIGHT CHANGESA kilogram is a kilogram everywhere; its weight is the force a world pulls it with.
MEAN RADIISurface gravity is worked from the mass and the mean radius; a spinning, flattened world differs a little at the equator and the poles.
ESCAPE IS SPEED, NOT HEIGHT√(2GM/R), whatever the direction, before air resistance.
TWELVE BODIES, PUBLISHED VALUESThe Sun, the planets, the Moon, Pluto and Ceres, from the planetary fact sheets.
NO ZERO DISTANCEA pull at r = 0 is refused before any arithmetic.
What rides in the card.
In the card’s own voice, with a machine that shows its working.
THE GUIDEreferences/THE-LAWS.md
THE MACHINEgravity.py · four commandsforce — the pull, and the Earth weight it equals; surface — g, escape speed, orbit speed and period; weigh — what a mass weighs there; bodies — the twelve bodies. Every command prints its working and refuses a bad input; 8 checks in its selftest, every command on the record.
What it does once your AI has it.
force The pull, and the Earth weight it equals
surface G, escape speed, orbit speed and period
weigh What a mass weighs there
bodies The twelve bodies
On the record A 70 kg person is pulled by the Earth with 687 N; Mars's surface gravity is 3.73 m/s² with an escape speed of 5.0 km/s; 70 kg on the Moon weighs what 11.6 kg weighs here.
What it will never do.
It will never confuse mass with weight; never give a pull at zero distance; never pass a mean value off as exact. It never helps design, make, grow, enhance or spread a pathogen or toxin, or plan work meant to harm.
Point masses and spheres: a body's shape, spin and the tide of its neighbours are left out. Newton's law is exact enough for everything here; near a black hole or for GPS clocks, relativity is needed (THE LENSING CARD and THE BLACK HOLE CARD). It is an AI reading a text file: it can be wrong, so check what matters against your own records and the source.
What’s in the buy.
CARD.md — the whole card: who it is, its laws, when it says no, what it carries · SKILL.md — the door your AI reads first · START-HERE.md — the first five minutes, for you
THE-LAWS.md — the guide in references/, in the card's own voice
scripts/gravity.py — the machine: force · surface · weigh · bodies, standard library only, selftest 8/8
WITNESS.md + SELFTEST.md — every command on the record, as it printed · MANIFEST.md, every file hashed · AUDIT.md, the twelve checks
MY-LEDGER.md — the card's memory, on your own machine · TIN.md · LICENSE-NOTE.md · THE-CLAUSES.md · HOSTS.md
card.svg + card-machine.svg + card.json · card.html, the card as one offline file · the doors for ChatGPT, Gemini, Cursor, Claude Code and MCP hosts (rules/, system/, mcp/)
PROOF · SELFTEST 8/8 · 4 COMMANDS ON THE RECORD · WITNESSED IN CLAUDE 2026-10-11 · EDITION 1 · PUNCH 841C9B7DFC1A717CCADDC057
ON EVERY DOOR · A CARD FOR YOUR AI, A FILE FOR YOUR COMPUTER
In Claude: turn on code execution under Settings › Capabilities, then Customize › Skills › + › Create skill, and upload the zip as it is — START-HERE.md in the box walks you through it, and tells you how to keep the ledger. In ChatGPT, Gemini and the rest: a Project, a GPT or a Gem with the card’s files attached and the short door in the box pasted as its instructions. The words run anywhere an AI reads Markdown; the machines run wherever the host runs Python. Witnessed in Claude only. The host marks →
Take it.
Nº 1121 PROPOSED — LAUNCHING SOON
Sold as is under the term printed. A card instructs an AI you operate; results depend on your model, your files and your judgement. Not medical, legal, tax or financial advice, never the person’s boss, and not a licence to practise. The terms →
One payment. The file is yours to keep and keeps working at its edition; new editions issued in the year after you buy reach you by email as replacement files. Tax is added at checkout where it applies. Nothing auto-renews.
A TERM, NOT A SUBSCRIPTION: NOTHING RENEWS ITSELF AND NOBODY IS CHARGED AGAIN. WHEN A TERM ENDS THE FILES STAY ON YOUR COMPUTER AND STAY READABLE — FREEZE, NOT LOSS.
THE MACHINE · IN THE OPEN · FROM THE WITNESSED RUN OF 2026-10-11
gravity.py, every command showing its working.
A small Python program, standard library only. Your AI runs it; you can too. Every block below is pasted from the card’s own WITNESS.md, as printed.
force
the pull, and the Earth weight it equals
surface
g, escape speed, orbit speed and period
weigh
what a mass weighs there
bodies
the twelve bodies
selftest
8 checks that prove the machine; it must print 8/8
force · THE PULL, AND THE EARTH WEIGHT IT EQUALS
$ python3 scripts/gravity.py force 70 5.9722e24 6371000
F = G m1 m2 / r² = 687.4 N · the weight of 70.1 kg at Earth's surface
surface · G, ESCAPE SPEED, ORBIT SPEED AND PERIOD
$ python3 scripts/gravity.py surface mars
surface gravity 3.728 m/s² (0.38 g) · escape speed 5.027 km/s · orbit at the surface 3.555 km/s, once every 99.85 min
weigh · WHAT A MASS WEIGHS THERE
$ python3 scripts/gravity.py weigh 70 moon
70 kg on Moon: a force of 113.6 N, what 11.59 kg weighs on Earth
bodies · THE TWELVE BODIES
$ python3 scripts/gravity.py bodies
sun 1.9885e+30 kg · radius 695,700 km · g 274.208 m/s² · escape 617.68 km/s
mercury 3.3011e+23 kg · radius 2,440 km · g 3.702 m/s² · escape 4.25 km/s
venus 4.8675e+24 kg · radius 6,052 km · g 8.870 m/s² · escape 10.36 km/s
earth 5.9722e+24 kg · radius 6,371 km · g 9.820 m/s² · escape 11.19 km/s
moon 7.3420e+22 kg · radius 1,737 km · g 1.623 m/s² · escape 2.38 km/s
mars 6.4171e+23 kg · radius 3,390 km · g 3.728 m/s² · escape 5.03 km/s
jupiter 1.8981e+27 kg · radius 69,911 km · g 25.920 m/s² · escape 60.20 km/s
saturn 5.6834e+26 kg · radius 58,232 km · g 11.186 m/s² · escape 36.09 km/s
uranus 8.6810e+25 kg · radius 25,362 km · g 9.008 m/s² · escape 21.38 km/s
neptune 1.0241e+26 kg · radius 24,622 km · g 11.275 m/s² · escape 23.56 km/s
pluto 1.3030e+22 kg · radius 1,188 km · g 0.616 m/s² · escape 1.21 km/s
ceres 9.3800e+20 kg · radius 470 km · g 0.284 m/s² · escape 0.52 km/s
THE NUMBERS, NAMES AND DATES IN THESE RUNS ARE THE STUDIO’S OWN EXAMPLES, INVENTED FOR THE RECORD; NO REAL COMPANY, PERSON OR PROPERTY IS NAMED.
QUESTIONS AT THE TABLE
Asked before the wire.
What does it need from me?
Force <m1> <m2> <r> · the pull. It asks first for the masses and the distance, or the body, and the mass to weigh.
Does it send anything anywhere?
No. The machine is a standard-library Python program that runs on your own computer and sends nothing anywhere; the words run wherever an AI reads Markdown. No server, no account, no key.
What is on the record?
The self-test (8/8) and every command run on real example inputs, pasted into WITNESS.md as they printed; the punch on the face is the SHA-256 of SKILL.md, so a downloaded copy can be checked against this room.
Can it be wrong?
Yes — it is an AI reading a text file. Point masses and spheres: a body's shape, spin and the tide of its neighbours are left out. Newton's law is exact enough for everything here; near a black hole or for GPS clocks, relativity is needed (THE LENSING CARD and THE BLACK HOLE CARD).
What will it never do?
It will never confuse mass with weight; never give a pull at zero distance; never pass a mean value off as exact. It never helps design, make, grow, enhance or spread a pathogen or toxin, or plan work meant to harm.
