What If You Shrank and Couldn't Stop?

Something goes wrong and you start shrinking, and it never stops. The bed rises past your chest. An ant walks past the size of a dog. A spilled drop of water pulls you in. Then you get smaller than the waves of light, and from there on nothing can be seen, only drawn: a bacterium, a strand of DNA, one oxygen atom, its nucleus, a single proton, and on past the smallest thing anyone has ever measured, down to the Planck length. The readout on the left is your height the whole way, and how many times smaller you are than when you started. The one on the right is how wide your room is to you. The ruler on the side runs from the observable universe at the top to the Planck length at the bottom; the white dot is you, the ring is your room. The numbers are real. Falling gets gentler as you shrink: a skydiver falls at about 55 m/s, a body a tenth the size at about 17. Below 2.7 mm, surface tension beats gravity and a drop of water can trap you. In powers of ten, the middle of everything, halfway between the Planck length and the observable universe, is about 0.12 mm, about the smallest speck you can see. At 20 µm water is like honey and swimming by kicking back and forth gets you nowhere. Visible light runs from about 380 to 700 nm, so below that light can't form an image of you. A proton's charge radius is 0.84 femtometres: at its size you have shrunk about a million billion times. The three quarks inside it make up only about 1% of its mass; nearly all the rest is energy. Nothing smaller than about 10^-19 m has ever been directly measured, which leaves about 16 powers of ten to the Planck length, 1.6 × 10^-35 m, that nobody has explored. Some of it is not real: Particle–antiparticle pairs are drawn as brief paired sparks. 'Virtual particles' are a picture from the calculations; nobody has watched one appear. You cannot really shrink; nothing in physics lets a person get smaller while staying a person. Below the size of an atom you would have no atoms left to be made of, so everything after that point is pure imagination. We never say what happens to your mass; if you kept it you would crush everything you touched, and if you lost it we cannot say where it went. A scaled-down human body would not work: a mouse-sized person would freeze and starve, and an ant-sized one could not breathe through human lungs. Your shrinking eyes would blur the world long before you reached ant size, and below the wavelength of light there is no sight at all, so every image after that is a visualisation. Below about 70 nanometres you are smaller than the distance an air molecule travels between collisions, so you could not breathe, hear or feel wind in any normal way. Inside the water drop you could not breathe, and below the size of a water molecule there is no "water" around you, only individual molecules. Atoms, electron clouds, nuclei and quarks have no colours or surfaces; the shapes and colours we show are conventions, like the colours on a map. Electrons are drawn as a glowing fog because they have no definite position, not because that is what they look like. Nobody has directly measured anything smaller than about 10^-19 m, so every scene below that line is a guess. You would run out of cells long before atoms: below about 7 micrometres you are smaller than one of your own cells, so a "you" at that size could not be made of cells at all. Quantum foam and the unification of forces are hypotheses, not discoveries. We don't know what, if anything, lies below the Planck length; the video stops there because current physics has nothing to say. The room width (4 m) and street length (100 m) are round numbers we chose, not measurements. The picture stays sharp down to about 600 nm; real eyes or lenses your size could not resolve a bacterium's surface, so those frames are a visualisation too. The rest of this list is in the pinned comment. The comparisons in the right-hand readout use a 4-metre room, and the room, the light and the furniture are made up. 0:00 Your room 0:46 Mouse-sized 1:25 An ant 1:45 The floor 2:28 Halfway 3:04 The drop 3:42 Bacteria 4:02 Smaller than light 4:44 Inside a bacterium 5:04 DNA 5:23 One molecule 6:30 The nucleus 6:43 One proton 7:33 The weak force 8:01 The edge 8:14 The desert 9:33 The Planck length 10:10 Your room Every number above is sourced; the full list of sources is in the pinned comment. Credits: "(муравей) Ant Rig VFX" by rayray (https://sketchfab.com/rayray_sss), CC Attribution: https://sketchfab.com/3d-models/ant-r... "Penny (Coin)" by Yanez Designs (https://sketchfab.com/Yanez-Designs), CC Attribution: https://sketchfab.com/3d-models/penny... "Tardigrade - SEM Microphotogrammetry" by ijdonnelly11 (https://sketchfab.com/ijdonnelly11), CC Attribution: https://sketchfab.com/3d-models/tardi...