No one puts new wine into old wineskins.

Luke 5:37

In 1920, Albert Einstein suggested a famous thought experiment. A man drops an object from his pocket while he is falling from the rooftop of his house. To him the object does not appear to be falling; rather, it remains stationary at his side. Einstein concludes that gravity and acceleration are equivalent, and that “free-fall acceleration is a powerful argument for extending the postulate of relativity to non-uniform motions between coordinate systems.”

This formulation of the equivalence principle can be extended to other realms of physics. In electromagnetic induction,...

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