an empirical study without actual data

an exercise in thinking through a problem from start to finish and in articulating the interpretation of a range of possible outcomes

an experiment you carry out in your brain, using only thinking - your imagination

Use of the imagination to investigate nature.

A thought experiment (from the German term Gedankenexperiment, coined by Hans Christian Ørsted) in the broadest sense is the use of an imagined scenario to help us understand the way things really are. The understanding comes through reflection on the situation. Thought experiment methodology is a priori, rather than empirical, in that it does not proceed by observation or physical experiment.