Tier 0 is the universal entry point. It requires nothing that cannot be found in any household. The question is the same as every other tier: what happens when you compare two clocks?
Start Here
Three Clocks That Disagree
Compare the Sun's shadow, a pendulum, and a household clock over 7–14 days. Discover that disagreement between clocks is data, not failure.
Sky Companion
A browser field notebook. Enter your observations, then compare them with the expected sky — solar noon, equation of time, Moon phase, and the bigger clock network.
What Tier 0 Teaches
A clock is defined by its comparison to another clock, not by its mechanism. Systematic deviations (the equation of time) are distinguishable from random scatter (reaction time, wind) if you have enough observations. No clock establishes its own correctness in isolation.
These ideas — comparison, systematic error, random error, reproducibility — are the same ideas used in every tier of this programme, from electronic oscillators to atomic clocks to pulsars.
Going Further
After completing Experiment 0.1, you are ready for Tier 1: Build — electronic oscillator comparison.