The Eternity Machine
A 3D machine of gears that has symbolically been running since the Big Bang. Each gear drives the next one — but six times slower. The first turns in about 3 seconds; the last needs 13.8 billion years for a single turn: as long as the universe has existed.
▶ Watch the machine live in 3DHow does it work?
Every gear has six times as many teeth as the pinion before it, so each stage turns six times slower. After only a few stages a gear moves so slowly that you would see no motion in a whole human lifetime. A red marker shows how far each gear has turned since the Big Bang.
From gear 18 on, a single turn takes longer than Homo sapiens has existed (about 300,000 years).
How one gear makes the next one slower
When a small gear (pinion) with 10 teeth drives a large gear with 60 teeth, the small one has to turn six times before the large one completes a single turn — the large gear runs six times slower, but with six times the force. This is called gear reduction. Put another small pinion on the same axle to drive the next large gear and the reduction multiplies: 6 × 6 = 36, then 216, 1,296… After 22 stages the ratio is 6²² ≈ 131 quadrillion to 1.
Time per turn of gear n = time per turn of gear 1 × 6^(n − 1)
Calculator: how slow does your gear train get?
Enter how fast the first gear turns, the reduction per stage and the number of gears.
Last gear: one turn in
14 billion years
= 1 × the age of the universe
Total gear ratio
1 : 1.316e+17
How long each gear takes for one turn
| Gear | One turn |
|---|---|
| #1 | 3.3 seconds |
| #2 | 20 seconds |
| #3 | 119 seconds |
| #4 | 12 minutes |
| #5 | 71 minutes |
| #6 | 7.1 hours |
| #7 | 43 hours |
| #8 | 11 days |
| #9 | 64 days |
| #10 | 386 days |
| #11 | 6.3 years |
| #12 | 38 years |
| #13 | 228 years |
| #14 | 1,369 years |
| #15 | 8,214 years |
| #16 | 49 thousand years |
| #17 | 296 thousand years |
| #18 | 1.8 million years |
| #19 | 11 million years |
| #20 | 64 million years |
| #21 | 383 million years |
| #22 | 2.3 billion years |
| #23 | 13.797 billion years |
Similar machines
The most famous relative is “Machine with Concrete” by the American artist Arthur Ganson: twelve gear pairs, each reducing 1:50, driven by a motor at 200 revolutions per minute. The last gear would need more than 2 trillion years for a single turn — so Ganson simply set it in concrete.
The “Clock of the Long Now” is a real mechanical clock designed to run for 10,000 years. The eternity machine goes further: it is calculated so that its last gear needs exactly the age of the universe for one turn — and it runs live, identical for every visitor.
Questions & answers
Does the last gear really turn?
Yes — mathematically exactly. Since the Big Bang it has completed exactly one turn; today it moves so slowly that nobody will ever see it move. Every gear's position is calculated from the current time and is the same for all visitors.
Why a ratio of 6?
60 teeth on the large gear and 10 on the small one give 1:6. That way 23 gears are enough to go from a 3-second gear to 13.8 billion years.
How much force would it have?
Reduction multiplies force: in theory the last gear would have 6²² times the torque of the first gear — in reality friction and materials would limit that.