> non-accelerating bodies Accelerated bodies in flat spacetime (Minkowski space) are well-described by special relativity. One can even calculate usefully in

> non-accelerating bodies Accelerated bodies in flat spacetime (Minkowski space) are well-described by special relativity. One can even calculate usefully in accelerated reference frames. https://en.wikipedia.org/wiki/Acceleration_(special_relativity) https://en.wikipedia.org/wiki/Acceleration_(special_relativi... The Unruh effect can happen in flat spacetime, for example, and is a useful check on Hawking radiation (in a black hole curved spacetime). It's also interesting in understanding the weak equivalence principle in detail; very loosely, a small-mass object can rest quietly on the surface of a non-compact, non-spinning, spherical mass eternally, while it is at least very difficult to keep the same small-mass object accelerating uniformly in flat spacetime for even fairly short (compared to say the age of the universe, which is hardly eternal) finite times.