Cosmic Distance Ladder Journey
Click through parallax (1/p), Cepheid period-luminosity, Type Ia standard candle, and Hubble flow d = cz/H_0. Each rung shows distance range and error; the cumulative error bar grows as you climb.
WHAT TO TRY
- Climb the ladder rung by rung, parallax to Cepheids to Type Ia supernovae to Hubble flow: each method only works over the band where it overlaps the one below, and that overlap is where it gets calibrated.
- Watch the cumulative error bar grow at every handoff: each rung inherits all the uncertainty beneath it, so Hubble-flow distances carry the whole chain budget.
- Notice the gaps: no single method spans nearby parallaxes to cosmological distances, which is exactly why the ladder is built in overlapping steps.