Lucien picked up a quill and drew two lines on the paper. "First of all, I admit that the system of relativity is very imperfect. It cannot explain inertia. It is also limited to the uniform-speed reference system and cannot be extrapolated to the uniform accelerated frame of reference."
"However, regarding the question that you presented, it is not a paradox in this case. Here are the timelines of the brothers, let's analyze them respectively. For the elder brother to fly away with a speed close to that of light, he would need an acceleration from stillness to his eventual speed, which is a process that cannot be neglected. If he intends to return, there would be another acceleration process in the opposite direction. It has to overcome inertia and cannot be neglected, either. In the meantime, considering the principles of relativity, the younger brother never overcame inertia…"
