1. The problem statement, all variables and given/known data Does Bohr's correspondence principle apply only to quantum theory? Can you give an example of the applications of this principle to relativity theory? 2. Relevant equations 3. The attempt at a solution According to my textbook, Bohr's Correspondence Principle simply states that in order for quantum theory to be correct, it must correspond to the predictions of classical physics in the region of sizes where classical theory is known to hold. For this reason, I said that it does not apply only to quantum theory. In particular, classical mechanics works for large masses and relatively low speeds. However, when the speed gets close to that of the speed of light, Relativity takes over. For relativity to be correct, however, at low speeds, it has to agree with classical mechanics (which it obviously does). However, I am not quite sure exactly what is meant by "give an example of the application of this principle to relativity theory." This makes me think that there is a specific part of SR that follows this principle, but the entire thing holds true. Do you think that it is sufficient for me to say what I said above? That is, just stating that at low speeds, relativity must agree with classical mechanics? Thank you.