Hi... Many times I have read articles about how strange inertia is and that no theory we have so far can not explain it etc. However I don't see that problem with it. What is so weird on inertia? It seems to me as normal thing that if some reference frame accelerate the particles in this frame are trying to stay with the velocity they had. It's probably because I really have knowledge of classical mechanics only. Please can you help me here and show me why Inertia is so interesting? Thank you.