## Conceptual Physics (12th Edition)

We don't ever encounter macroscopic objects moving near the speed of light. The effects of relativity become noticeable only when speeds approach the speed of light, or when energies change by amounts comparable to $mc^{2}$. In our everyday world, things move much more slowly than c, and we don't generally have access to particle accelerators or nuclear power plants. Classical mechanics makes sense, based on everyday experience, while relativity doesn't.