Gedanken
A thought experiment or Gedankenexperiment (from German) considers some hypothesis, theory, or principle for the purpose of thinking through its consequences. Given the structure of the experiment, it may or may not be possible to actually perform it, and, in the case that it is possible for it to be performed, there need be no intention of any kind to actually perform the experiment in question. The common goal of a thought experiment is to explore the potential consequences of the principle in question.
Famous examples of thought experiments include Schrödinger's cat, illustrating quantum indeterminacy through the manipulation of a perfectly sealed environment and a tiny bit of radioactive substance, and Maxwell's demon, which attempts to demonstrate the ability of a hypothetical finite being to violate the second law of thermodynamics.
Read more about Gedanken: Overview, Variety, Origins and Use of The Literal Term, Uses, In Science, Relation To Real Experiments, Causal Reasoning, In Philosophy