Thought Experiment
Considers some hypothesis, theory, or principle for the purpose of thinking through its consequences, often because to run the actual experiment is unfeasible, expensive, or dangerous.
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Origin
The term traces to Danish physicist Hans Christian Ørsted, who first used the German Gedankenversuch — "thought-trial" — around 1812. Austrian physicist Ernst Mach later refined and popularized Gedankenexperiment in an 1897 paper; the English calque "thought experiment" appeared the same year in translation. Mach's influence reached Albert Einstein, who relied on the method throughout the development of relativity.
Updated February 22, 2026