Is it a "clump" because we are on the train...Or, because we are standing beside the tracks?
Is it a "clump" because we are on the train...Or, because we are standing beside the tracks?
The more an object with mass approaches light speed, the slower its clock appears to tick (from our stationary outside reference frame). Also the greater its mass increases, again, from our perspective. I don't know how we would be able to know what its intrinsic mass was.