Number & MeasureGreek → English
Ergodic
/ɜːrˈɡɒdɪk/adjective
Describing a system whose long-run behaviour over time matches its average over all possible states.
The Greek roots
ἔργον
érgon
work, deed
ὁδός
hodós
way, path
Literally: “work path”
The story of the word
Boltzmann coined the German original in the 1880s for statistical mechanics, and the parsing is genuinely contested: the standard reading is ἔργον plus ὁδός, a path through the energy surface, while some historians of science argue for ἔργον plus εἶδος, work-form. The idea it names is easy to state and hard to prove: watch one system for long enough and you see what you would see by looking at every system at once. Whether a given system is ergodic is usually the hardest question in the room.
- How it travelled
- Ancient Greek → German → English
- First recorded
- early 20th century
Same family
energyergonomicssurgerymethodexodus
In a sentence
If the process is not ergodic, a single long run tells you about that run and nothing else.