How things work
100 questions the world already has. Falling, flowing, heat, light, charge, the night sky, why atoms have a size. An accurate first-principles picture of ordinary things — not a syllabus, and not this plant.
Primer will still define every technical word, still refuse invented numbers, and still mark the locally-true story that breaks. It will not close like an owner’s rep on a drawing.
Fall, flow, heat Light, gravity, sky Light and charge Quanta and size Inside matter 24 questions
Fall, flow, heat Pushes, flowing stuff, and energy on the move. Same physics on a street as in a lab.
Why do things fall? Open Why doesn't a heavier hammer hit the ground first? Open Why don't we feel the Earth spinning? Open Why is ice slippery? Open Why does ice float? Open How does a siphon move water up and over a rim? Open How does a suction cup stick to a window? Open How does a hot-air balloon rise? Open Why does metal feel colder than wood at the same temperature? Open How does a thermos keep a drink hot? Open How does a kettle boil water? Open How does a refrigerator keep food cold? Open What is a heat pump actually moving? Open Why does water boil at a lower temperature high in the mountains? Open Why does popcorn pop? Open How can a sailboat make progress upwind? Open Why does a fountain jet rise only so high? Open How does a toilet flush? Open Why does a moving bicycle stay upright more easily than a parked one? Open What is the difference between force and energy? Open What is momentum, and why does a heavier cart need more distance to stop from the same speed? Open Why does a room's ceiling often feel warmer than its floor? Open How does a pendulum keep approximately even time? Open In what sense is a thrown ball taking the laziest path? Open 18 questions
Light, gravity, sky A maximum signal speed, gravity as geometry, and what the night sky is actually saying.
Why is there a maximum speed for ordinary travel? Open What is light, as a physical thing? Open Why is the night sky dark? Open Why do GPS clocks have to account for relativity? Open If you run toward a flashlight beam, does the light meet you faster? Open Why does gravity bend starlight? Open What is a black hole in established physics? Open Why do we describe gravity as geometry rather than a pull through empty space? Open Why do moving clocks tick slower, as something you can compare after a trip? Open What does E=mc² say about the inertia of energy? Open Why doesn't a freely falling cabin feel gravity? Open What is a gravitational wave? Open Why do stars twinkle from the ground but not from orbit? Open Why can't you outrun light by adding two fast speeds together? Open What is an event horizon, observationally? Open Why does a clock run differently higher up a mountain than at sea level? Open Why do both mass and energy affect gravity? Open What happens to time and space near a very compact mass, without mysticism? Open 22 questions
Light and charge Charge, fields, and the light you actually see. Motors, magnets, sky, and a kitchen microwave.
Why is the sky blue? Open Why is a sunset red? Open How does a rainbow form? Open How does lightning form? Open How does a compass needle find north? Open How do eyeglasses correct blurry vision? Open How does a loudspeaker make sound from an electrical signal? Open How does a guitar string pick a pitch? Open How does a magnet attract a refrigerator door? Open Why does a battery have two ends? Open How does an electric motor turn a shaft? Open Why can a bird sit on a high-voltage wire without being shocked? Open Why does a household fuse melt? Open How does a camera flash store energy before it fires? Open What is actually different between an LED lamp and a flashlight filament? Open How does a solar panel produce electric current? Open Why can you see through glass but not through a brick? Open How do polarized sunglasses cut glare off water? Open How does a microwave oven heat food? Open What is an electromagnetic wave? Open Why does a rubbed balloon stick to a wall? Open How does an induction cooktop heat a pan without a red coil? Open 18 questions
Quanta and size Why atoms have a size, why a floor holds, and why 'quantum' is not a blank check.
Why do atoms have a size at all? Open What is a photon? Open Why do things have color? Open Why don't we fall through the floor? Open Why is a quantum of action not a license for anything to happen? Open Why does a heated iron bar go from red toward white? Open Why don't electrons spiral into the nucleus? Open What does superposition mean as a physical statement, not a metaphor? Open Why is there a smallest packet of light energy for a given color? Open Why are solids hard to squeeze? Open Why doesn't quantum tunneling let you walk through a wall? Open What is Planck's constant doing in the size of atoms? Open How does a laser make a tight beam? Open Why does a digital camera collect light in counts? Open Why do chemical bonds come in definite steps? Open Why is a fluorescent tube a different kind of light than a candle? Open What does it mean that electrons in an atom are not tiny planets? Open Why is a neon sign a particular color? Open 18 questions
Inside matter Nuclei, stars, chips, and muscle as a machine. Established physics, no extra ingredients.
What is the Sun actually fusing? Open Why do nuclei stick together if protons repel? Open How does a semiconductor let current through only sometimes? Open How does a muscle fiber pull, as a physical machine? Open Why is hydrogen common and gold rare? Open What is radioactivity? Open How can a smoke alarm use a radioactive source? Open Why can a star shine for billions of years? Open What is a transistor doing to a current? Open Why is iron a dead end for fusion in ordinary stars? Open How does an LED make light at a junction? Open Why does a battery eventually go dead? Open What is a neutron doing inside a nucleus? Open How does MRI distinguish tissue without cutting? Open Why do computer chips need extremely pure silicon? Open How is fusion in the Sun different from chemical burning? Open Why can uranium nuclei split? Open Why does a nucleus store far more energy than a chemical bond, without a cookbook number? Open