six thresholds where a different physics begins · every figure computed, not typed
Built as a memo rather than a table: the thing worth hanging it up for reads across the room, with the full reference in smaller type below it.
Three sizes in one archive — from a sheet on the fridge to a poster on the wall.
The scale is logarithmic: each labelled mark is ten times the one before it. The second figure in a row is how many times that speed exceeds the speed of sound in air.
The ceiling is 299 792 458 metres per second, and it does not move. In water, though, light travels slower: a refractive index of 1.3330 brings it down to 224 900 kilometres per second. That limit is no longer the ceiling, only the speed of light in this particular medium, and a quarter of the scale still lies above it.
A particle fits into that quarter. An electron knocked out by radioactive decay moves through water faster than light does there, and leaves a cone of radiation behind it, exactly as an aircraft leaves a shock wave behind the speed of sound. That cone is the blue glow seen in the water above the core of a nuclear reactor.
Pavel Cherenkov saw the effect in 1934, Ilya Frank and Igor Tamm explained it in 1937, and in 1958 all three received the Nobel Prize in Physics for it.
Why the numbers can be trusted. Every countable number here is computed from data rather than typed in, and the sheet must pass 9 independent checks before it is allowed to build — how many items there are, the order they come in, and the claim in the highlighted box itself. If one fails, there is no file.
from the Challenger Deep to the summit of Everest · one scale, nothing compressed
from the first synapsid to us · 320 million years on one axis
when each group appeared · five hundred million years on one axis
fifteen formulas · every letter explained beneath it