Somewhere in the Netherlands, a small machine made of ordinary gears has been quietly running for years, and its final gear has not moved. It never will, not in your lifetime, not in humanity's lifetime, not in the Sun's lifetime. That's not a design flaw. It's the entire point. This is the googol gear machine, a real, physically built device engineered to demonstrate just how incomprehensibly large the number googol actually is, one gear tooth at a time.
01 · The Idea
A Birthday Gift From an Engineer to Himself
📍 Daniel de Bruin · The Netherlands · One Billion Seconds Old
The machine traces back to Dutch designer Daniel de Bruin, who built it to mark an unusual milestone: turning exactly one billion seconds old. To celebrate, he built a gear train with 100 connected gear pairs, each one reducing the rotation speed of the next by a factor of ten. Turn the first gear ten times, and the second gear turns once. Turn the second gear ten times, and the third gear turns once. Repeat that pattern one hundred times in a row, and the overall reduction between the first gear and the last comes out to almost exactly a googol to one, a 1 followed by 100 zeroes.
De Bruin has said the number is so large it exceeds the total count of atoms in the observable universe, and that turning the final gear a single full rotation would take more energy than the universe could ever supply.
02 · Built Again, in LEGO
Someone Rebuilt It Out of LEGO, and Did the Exact Math
📍 Brick Experiment Channel · 186 LEGO Gears
De Bruin's build inspired the YouTube creator behind Brick Experiment Channel to attempt the same feat using nothing but LEGO parts. The result used 186 LEGO gears and landed on a total gear ratio of roughly 1.034 times ten to the power of 100, just a touch over an actual googol. Using precise calculator software to avoid rounding errors, the builder calculated exactly how long the final gear, holding a tiny LEGO minifigure statue, would take to complete one single rotation.
📊 The calculated answer: one full rotation of the last gear would take approximately 5.24 × 10⁹¹ years, a number so large that essentially nothing in the physical universe as we understand it is expected to still exist by the time it happens.
03 · Putting the Numbers on a Timeline
What Might "Happen" by Each Gear's Turn
📍 Deep Time · A Sense of Scale
Numbers like 10⁹¹ don't mean much on their own, so it helps to line them up against things we can actually picture. The table below walks through the LEGO googol machine's gear stages, roughly how long each one takes to complete a single rotation, and what else could plausibly happen in that same span of time, based on current science.
| Gear Stage | Time for One Rotation | What Else Happens in That Time |
|---|---|---|
| 1st gear pair | Under a second | A single human eye-blink |
| 6th gear pair ("minute hand") | About an hour | A short movie, or one work meeting |
| Planetary output gear | ~600 years | Roughly the span from the Mughal Empire's rise to today |
| Mid-train gear (~stage 60) | ~13.8 billion years | The entire current age of the universe, start to now |
| Mid-late gear (~stage 70) | ~5 billion years | Roughly when our Sun is expected to run out of fuel and die |
| Late gear (~stage 100, per physicist estimates) | ~10¹⁰⁰ years | The rough point by which all black holes are predicted to have evaporated via Hawking radiation |
| Final (100th) gear | ~5.24 × 10⁹¹ years | Long past the point most physicists expect stars, black holes, and even atoms to have broken down entirely |
Timescale comparisons are drawn from current physics estimates for stellar lifespans, the age of the universe, and black hole evaporation timelines, and are approximate.
04 · The Physical Limits
Why the Last Gear Can Never Actually Be Watched
📍 Beyond Classical Physics
Past a certain point in the gear train, the question stops being mechanical and starts being physical in a deeper sense. Engineers who've examined the LEGO version point out that once you calculate how far a single tooth on the first gear would need to travel for the last gear to move by even one Planck length, the smallest meaningful unit of distance in physics, the number of rotations required is itself absurd. In practical terms, no gear train can outlast the atoms it's built from; long before the final gear could complete even a fraction of a rotation, the gears, the axles, the motor, the Earth itself, and eventually the Sun, would all be gone.
05 · Is It Real, or Just a Thought Experiment?
Real or Theory: The Honest Answer
📍 Both, Depending on What You're Asking
The machine itself is completely real. Daniel de Bruin's original build exists, runs, and has been filmed. The LEGO recreation by Brick Experiment Channel is equally real, built from off-the-shelf LEGO Technic gears with every rotation ratio independently calculated and verified. Both machines were inspired by an even earlier real artwork, Arthur Ganson's "Machine with Concrete," a gear-reduction sculpture on permanent display at the MIT Museum, whose final gear is deliberately embedded in solid concrete because it will never move regardless.
What's theoretical is the outcome, not the object. The gears genuinely exist and genuinely turn according to real, verifiable mechanical ratios. But the claim that the last gear "will rotate once in 5.24 × 10⁹¹ years" is a mathematical projection, not something anyone will ever witness, because no physical machine, planet, or civilization is expected to survive anywhere close to that long. So the honest summary is this: the machine is real engineering, built and running today. The number it's designed to reach is real mathematics. What it demonstrates, that a googol is a number so large it dwarfs the age of the universe itself, is where the real world quietly hands off to pure theory.
Worth remembering: you don't need the machine to finish turning to get its point. The moment you understand that its very first six gears already outrun anything the human eye can track, and that ninety-four gears still remain after that, is the moment the actual size of a googol stops being an abstract math term and starts being something you can feel.