Relativity and the speed of light - A 100 year old misunderstanding

I point out a conceptual misunderstanding in the exposition of relativity, namely the mistaken belief that light has something to do with the essence of relativity. This misunderstanding can be clarified by stressing that the content of Special Relativity is simply that "we live in a Minkowski spacetime", together with a thought experiment that illustrates how one could discover this fact without ever mentioning even the existence of light. I also note a recently uncovered implication of living in Minkowski spacetime, namely the Copenhagen reinterpretation of Quantum Mechanics, developed in the past decade.