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Black Holes, drawn

aboutAttribution

This site was built at Hongdam in Chiang Rai, by Nan. Every picture on it was computed for it; every diagram was drawn from the equation it shows; every fact has a source on the sources page.

Use it

Text, pictures and diagrams: Creative Commons Attribution 4.0. Copy, adapt, print, teach from, sell. The one condition is a credit — “Nan · hongdam.net · CC BY 4.0” — with a link to https://nanobotco.github.io/black-holes/. Code, in tools/ and js/: MIT.

What is not this site's to give: the quotations, which belong to their authors and are used in brief with their sources named; the Nietzsche and Zimmern texts, which are out of copyright; and the results cited, which are their discoverers'.

Cite it

Nan (2026). Black Holes, Drawn: mathematical modelling of black holes, with pictures.
Hongdam, Chiang Rai. https://nanobotco.github.io/black-holes/  CC BY 4.0.

What was checked, and how

The ray tracer reproduces Luminet's 1979 figure, the arch-and-band shape of the Interstellar renders, and the 2.6-to-1 shadow-to-horizon ratio. The shadow generator reproduces the D-shape Bardeen drew and the EHT's measured sizes for M87* and Sgr A* to within their error bars from the published masses and distances. The chirp generator reproduces GW150914's 0.2-second duration from 35 Hz and its ~250 Hz ringdown. The calculator's constants are CODATA 2018. The dates on the past page follow the primary papers listed; where popular accounts disagree (who first said “black hole”), the page says so.

Numbers on this site are computed at build time from the formulas, not typed in: the horizon radii, the temperatures, the shadow sizes, the tides. Change a constant in tools/figures.py and the pages change.

Not on this site

Photographs from the Event Horizon Telescope, LIGO's strain plots, Luminet's original — all are their institutions' and are linked, not copied. Wormholes, white holes and the inside of the horizon beyond what the equations say. Astrology: Rahu is here as the model of an invisible thing with a period, which is what the astronomers who computed him made, and the offering list is recorded as practice.

Build

python3 tools/render.py     # the ray-traced pictures, ~4 minutes
python3 tools/figures.py    # the diagrams and build/facts.json
python3 tools/site.py       # the pages, into build/site/
./publish.sh                # all of it, checked, into docs/