What it is for
A twin is a computer copy of a real place. This one runs a city under the dunes that rides out every threat on the list, asteroid included, and stays a good place to live.
Point Lookout · Copernicus Sentinel-2 · sources
Close to home
Your tap. The mainland has been drinking this island since 1996. Eight Olympic pools a day, one every three hours. The island itself uses two thirds of one.
Your power bill. Nobody has measured the swell out the front. One estimate puts half a kilometre of it at six times what the whole island gets through, day and night, rain or shine.
The car queue. $41 million is committed to the new terminal, staged over years. It still does not say where you park. About 375,000 people visited in 2018 against 2,200 residents, and in peak weeks the population triples.
Amity Point. It is losing ground to the sea. Houses, the road, the rock wall.
When the barge stops. The shelves empty. Same as any town on one road.
Work. Young people leave the island for jobs that could be here.
The north star
One ladder from the Gumpi jetty to a civilisation that keeps the lights on through anything.
Grain by Grain, PLAN.md, section 1.
Kardashev Type 1 means a place uses all the energy that already lands on it. Further up the dial "just means a bit steadier, and a bit kinder to the place".
A subterranean eco-city, a closed-loop ecosystem, that could survive and thrive through and beyond every threat on the threats page (asteroid impact included).
PLAN.md, section 3.
Where the numbers get hard
There is no bridge. Fresh water sits in the sand under the island, and that body of water is called the lens. The coast moves. The mainland pulls about twenty megalitres a day out from under it: eight Olympic pools, one every three hours, day and night. All of it at a size you can walk across.
The horizon rule
From the threats page: "'This decade' means expect it; 'this century' means plan for it; 'deep time' means build a civilisation that outlasts the question."
Why the list needs no argument
The threats page lists them all, from the next bushfire to an asteroid.
Fire, flood, storm, blackout, pandemic, solar storm, worse: strip away the causes and the needs underneath are nearly identical.
Build the agreed things now, while people argue about the rare ones. The same water, power, food and shelter work covers both.
Nobody has to win that argument for the work to make sense.
Grain by Grain, threats.html and method.html.
Underneath all of them
Things fall apart on their own. That is entropy. The page calls it the master threat: "The moment a civilisation stops organising, entropy resumes consuming its systems, its knowledge and its people."
"Joyful responsible abundance is what winning slowly looks like."
Ranked first
A micro-nova is a sudden burst of energy off the sun, big enough to wreck the grid. The founder ranks it first.
Snowball Earth, the planet freezing over, tests it hardest. A civilisation that can "live warm under the sand on banked energy while the surface freezes" has answered every smaller cold snap for free.
Why a twin
If a thing looks possible, SIMULATE it first; only if simulation shows it genuinely necessary do you dig.
PLAN.md, section 3.
Grain by Grain says it plainer: "You would build the whole thing first inside a computer and run it against every threat, until you found where it broke."
Everything moves together
Tide, weather, the fresh water, the sand core, the dug-out sand and the power load move together, or the answer is wrong. The first build calls it rehearsal: plans are "tested as simulations before anyone spends money, goodwill or Country on them".
It survives the room
A block at Amity Point needs rezoning. Rezoning means the government changes what the land can be used for, and it is slow and political. The strongest thing to bring is "a model anyone can check". Across the whole build, "claims become runnable models anyone can re-run".
It gets ahead of the law
Federal law bans nuclear power here. Thorium is a reactor fuel instead of uranium. "A Straddie student can build a virtual thorium reactor now, stress-test it against real physics, and be years ahead on the day the law changes."
The island owns it
MODFLOW is free groundwater software that works out how water moves through sand. An open MODFLOW twin of the lens means "the community ends up owning the model that any future decision depends on".
Three words together
People have to come out the other side wanting to be alive. "Any two are easy. It is the third that makes it hard."
Joy plus abundance, no responsibility
"Every extraction boom in history threw a good party first."
Joy plus responsibility, no abundance
"It burns out its best people and calls the burnout virtue."
Responsibility plus abundance, no joy
"Everything accounted for, nothing worth accounting for." A place run like that is safe until everyone quietly leaves.
A shelter that keeps people breathing and gives them nothing to stay for empties out. The plan asks "how people live well, not merely survive, during stress".
A sand-sports ground and a cinema sit in the tunnel corridor: "somewhere for a Saturday and a film night".
One line in the files covers it: "enough, made well, made yours, made to last, and nothing thrown away that another process wanted."
How to judge a twin
A twin needs threats it can run, measurements you could build from, and the rules that decide what gets built. Neither Minjerribah build has all three today. The ledger names the missing parts.