Light cones: why saying now about Alpha Centauri is a convention and not a fact

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The Andromeda paradox: two walkers passing each other disagree about whether a fleet has already launched Minkowski in 1908: space by itself and time by itself are doomed to fade into mere shadows Presentism has no observer-independent now to hang on once relativity is in play The train and the two lightning strikes: how Einstein's 1905 thought experiment killed absolute simultaneity Michelson and Morley found nothing in 1887 and that null result became physics' most useful measurement The twin paradox: the traveller really is younger and acceleration is what breaks the symmetry The Wheeler-DeWitt equation has no t in it: what the problem of time means for quantum gravity Two observers disagree about distance and duration but always agree on the spacetime interval Gravity Probe B's gyroscopes and the dragging of spacetime by a rotating Earth The speed of light is not really about light: it is the exchange rate between space and time