I'm using an uncalibrated scale intentionally, as that's exactly what we're doing when we talk about taking two clocks and moving one of them at relativistic sp

I'm using an uncalibrated scale intentionally, as that's exactly what we're doing when we talk about taking two clocks and moving one of them at relativistic speeds. That two identical instruments in different gravitational fields will exhibit different measurements. With mass this makes sense to us, because we can compare with a constant - we can take the same item with a constant mass and measure it in two different gravities - and because it happens on scales we can perceive. Men bouncing around the moon is a perceivable change. An astronaut coming back from a year on the ISS, being biologically 12.5 seconds younger than if he hadn't gone, is far too glacial for humans to perceive. Of course, we could just argue that relativity is a myth and the clocks just need to be calibrated.