01 / THE CORE
EIGHT MINUTES OLD.
A HUNDRED THOUSAND
YEARS IN THE MAKING.
γ · 26.7 MEV
This is the story of the light that is hitting you right now.
It begins as violence. In the core, two hundred and fifty billion atmospheres of pressure hold hydrogen close enough to fuse. Four nuclei become one helium, and the missing mass leaves as light: a gamma photon, furious and newborn, in the one place the sun keeps darkest. It knows nothing. It will spend the next hundred thousand years learning the way out.
- PRESSURE: 2.5×10¹¹ ATM
- FUSION: 4 ¹H → ⁴HE + γ
- ENERGY: 26.7 MEV
BEGIN THE WALK ↓
02 / THE WALK
ONE CENTIMETER
AT A TIME
In the radiative zone, a photon travels less than a centimeter before something takes it. Absorbed, re-emitted, absorbed again — a random walk counted in sextillions of collisions, each one erasing its sense of direction.
MEAN FREE PATH ≈ 1 CM
COLLISION 10¹⁹
If you straightened its path, it would reach across the galaxy. What it actually gained was seven hundred thousand kilometers: one solar radius, covered at the speed of light, over roughly a hundred thousand years.
COLLISIONS ~10²¹ · PATH IF STRAIGHTENED: A GALAXY WIDE
COLLISION 10²⁰
It is the most patient thing in the universe, and it does not know it is going anywhere.
COLLISION 10²¹ — ALMOST OUT
You, dragging your cursor through the plasma, are one more thing it collides with.
03 / PHOTOSPHERE
ESCAPE
After a hundred thousand years, the rest of the trip takes eight minutes.
SURFACE: 5,772 K · GRANULE Ø ≈ 1,000 KM · LAST SCATTERING: NOW
ESCAPE VELOCITY: NOT REQUIRED. IT IS LIGHT.
04 / THE CROSSING
THE QUIET CROSSING
- 00:00 — PHOTOSPHERE, DEPARTURE
- 03:13 — MERCURY ORBIT
HOLD ANYWHERE — SEE HOW FAR LIGHT GETS WHILE YOU WAIT
Nothing touches it. For the first and only time in its life, it travels in a straight line.
- 06:01 — VENUS ORBIT
- 08:18 — THE MOON, ONE SECOND AWAY
- 08:19 — EARTH, UPPER ATMOSPHERE
The sun you see is always the sun as it was. You have never once seen it as it is.
DISTANCE: 1 AU = 149,597,870 KM · TRANSIT: 499 LIGHT-SECONDS
05 / THE SKY
WHY THE SKY
IS BLUE
Eight minutes of nothing, then everything at once: the atmosphere. Air is nearly transparent — nearly. Blue light, at four hundred and fifty nanometers, scatters about six times more strongly than red at seven hundred. The sky is blue because it is full of sunlight that didn’t make it straight through. Every clear day is a story of ten thousand small collisions, retold above your head.
DRAG ACROSS THE SPECTRUM — 380–700 NM · SCATTERING ∝ 1/λ⁴
λ 450 NM — SCATTERS ×5.9 VS 700 NM
RAYLEIGH, 1871 · σ ∝ 1/λ⁴
Our photon keeps its line. It was aimed, by accident, at you.
06 / THE EYE
ARRIVAL
It ends in a molecule of rhodopsin, in a rod cell, in an eye. The cell fires. A hundred thousand years of stubbornness becomes one quiet electrical word: light. A single photon is enough.
- YOU HAVE BEEN LIT FOR 00:00
- PHOTONS RECEIVED FROM THIS PAGE (EST.): 0
- 00:00:00 — LOCAL
Every photon this page has shown you finished its own journey in your eye.