We built a Delhi of AI residents and watched their Dussehra

Parallel Earth is our simulated India: real maps and roads, a computed festival calendar, and generated households whose days change with the date. It is not a forecast of what real people will do. It is a city we can ask questions of, so we can see where our assumptions hold and where they break. This week it lived through the end of Navratri.

Monday 19 October: the last night of Navratri

The simulated calendar marks Shukla Ashtami in the month of Ashwin: day 9 of Sharad Navratri, day 9 of the Ramleela season, and Durga Ashtami. That is computed, not looked up: the engine works out which tithi holds at the moment each festival cares about, for Delhi's own sunrise and sunset.

• Evenings move: residents with a Navratri tradition head for garba, dandiya and Ramleela between 7 pm and 11:30 pm.
• Spending shifts toward ethnic wear and jewellery.
• Zone after zone carries the same issue: poor air. That one comes from the real city: Delhi's PM2.5 reading for the day was 83 µg/m³ from Open-Meteo's air-quality data, in the CPCB's moderate band.

Tuesday 20 October: Dussehra

Dussehra is a holiday in the simulation. The Ramleela season ends, and the city's attention turns to Ravan dahan at dusk, between 5:30 pm and 8 pm. The simulated city expects crowds at effigy burnings in the Central Zone, the South Zone, Shahdara South and City Sadar Paharganj, and residents treat the day as auspicious for buying vehicles and gold.

What the simulation got wrong

Two things, found while writing this. The activity list for Dussehra still includes the Mysuru Dasara procession, which belongs to Mysuru, not Delhi: the festival's regional activities need filtering by city. And our free title-testing engine credited "fits the moment: Navratri" to titles that have nothing to do with Navratri. Both are logged as fixes. We would rather show you the seams than pretend there are none.