A Photon's Epic Journey
Like Duolingo, but for A Photon's Epic Journey. Tomo turns the whole topic into a game you play five minutes a day, until it actually sticks.
For the part of you with thirty open tabs that never became anything.
Free forever · No credit card · iPhone & Android

Key ideas in A Photon's Epic Journey
- Extreme pressure and heat in the core force atoms to collide
- The Sun's interior is packed so tightly with particles that photons constantly collide
- The process of atoms smashing together (fusion) releases light as a byproduct
- Every collision deflects the photon in a new, unpredictable direction
- The origin of light in the Sun's core
- The physical movement of a photon through the Sun's interior
- Photons start as invisible, high-energy radiation in the core
- Constant collisions drain the photon's energy
- The zigzag path is so inefficient it adds millennia to the journey
- A photon can spend over 100,000 years just trying to reach the surface
- By the time it reaches the surface, it has 'cooled' into the light our eyes can see
- The Sun doesn't have a solid surface, just a layer where density drops
- The scale of time required to exit the Sun
- This 'departure lounge' is the part of the Sun we actually see from Earth
- The transformation of light energy during the journey
- The point of escape from the Sun's density
You've tried the other tabs
Thirty open tabs. Four facts you actually kept.
You watched. You nodded. By Sunday it was gone.
One answer, then back to scrolling.
Eight weeks. You meant to finish. You didn't.
Tomo gives A Photon's Epic Journey the Duolingo treatment: levels, streaks, and quick quizzes that test what you just learned. That game loop is what the tabs above never had, so it's the one you actually finish.
Here's what playing it feels like
A real question from this course. Take your best guess.
Why can't a photon travel in a straight line through the Sun's interior?
Get it right to open this lesson and 6 more in the app.
Where A Photon's Epic Journey takes you
Follow a single, self-aware particle of light on its chaotic 100,000-year escape from the Sun's core to its final destination: your skin.
- 1
The Great Solar Escape
- The Thousand-Year Bumper Car Race
- 2
The Sprint to Earth
- Eight Minutes of Pure Speed
- The Final Landing
2 sections · 3 units · 7 levels. Built to play, not to enroll.
You pick the voice
A Photon's Epic Journey is taught in the The Professor style: clear, structured, thorough. Want a different feel? In the app you can spin up the same topic in any of Tomo's teaching styles. Same facts, totally different vibe.
More Science on Tomo
Exoplanets and the Search for Life
An exhaustive exploration of planetary systems beyond our own, from the subsurface oceans of icy moons to the detection of biosignatures in the deep cosmos.
The World of Dinosaurs
Move beyond the basics of the T-Rex to explore the complex evolution, specialized clades, and surprising biology of the Mesozoic's most successful inhabitants.
Fingerprint Analysis: The Art of the Lift
Learn to reveal the invisible world of latent prints. Master the tools of the trade to lift evidence and develop the sharp eye needed to match ridges like a professional investigator.
Genomic Engineering & Regulation
Move beyond the basics of inheritance to master the tools of modern genome editing and the complex regulatory layers that dictate cellular identity.
Biology: The Logic of Life
Move beyond memorizing parts to understanding the systems that drive all living things. Explore how energy, information, and environment interact to create the complexity of the natural world.
Gravity's Extremes: From Big Bang to Black Holes
Explore how the curvature of spacetime dictates the birth of the universe and the mysterious physics of its most dense objects.
Start A Photon's Epic Journey today.
Download Tomo, search A Photon's Epic Journey, and play your first lesson in under a minute.