I happened to listen audiobook Brian Greene - Fabric of the Cosmos. There were great explanations and nice metaphors, but I still don't get it. Let just imagine hypothetically, that Bart is ready for launch to Mars with his nuclear-powered skateboard, next to him is radio antenna ready to broadcast Bart's favorite cartoon to the TV, which is located on Mars (and Homer sits in front of it). Bart's take-off and broadcasting start simultaneously. Would Bart make it on time? Or would he be hopelessly late? Given that his skateboard could instantaneously develop speed 299 000 kilometers per second (Near the speed of electro-magnetic wave) and distance to mars is 150 000 000 km. As I understand in Homer's perspective, Bart would be there almost on time. And for Bart's perspective he would be hopelessly late. But who is the person that Homer sees flying in from the window and cheering that he made it?