Thought experiment
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In physics and other fields, a thought experiment (from the German Gedankenexperiment) is an attempt to solve a problem using the power of human imagination. These experiments are used to attempt to understand something about the universe. There are many famous thought experiments from the nineteenth and especially the twentieth century, but the practice goes back at least as far as Galileo.

Famous thought experiments include:

Physics

• Galileo's ship (classical relativity principle) 1632
• Maxwell's demon (thermodynamics) 1871
• Twin paradox (special relativity)
• Schrödinger's cat (quantum mechanics)
• EPR paradox (quantum mechanics) (forms of this have actually been performed)
• Quantum suicide (quantum mechanics)
• CHSH inequality (quantum mechanics)
• GHZ experiment (quantum mechanics)
• Wigner's friend (quantum mechanics)
• Richard Feynman's "Brownian Ratchet" (a "perpetual motion" machine which does not violate the second law, and does not work)
• Cones (Basis for almost perpetual motion machine fueled by entropy)

Philosophy

• Brain-in-a-vat (epistemology)
• Chinese Room (philosophy of mind, artificial intelligence, cognitive science)
• The Ship of Theseus (concept of identity)
• Simulated reality (philosophy, computer science, cognitive science)
• Swamp man (personal identity)
• Trolley problem (ethics)
• Original position (politics)
• Coherence (philosophical gambling strategy)

Miscellaneous

• Infinite monkey theorem (probability, infinity)
• Entries on thought experiments: http://www.people.cornell.edu/pages/tsg3/thoughtexperimententry.pdf

http://plato.stanford.edu/entries/thought-experiment/

The original article can be found at: http://en.wikipedia.org/wiki/Thought_experiment.
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