Objects in our universe Enormous range of sizes
Classical Mechanics works very well for ordinary objects around us:
- Scale of size ~ 1m -- From the smallest object you can see ~10-4 m to Planets of order 107 m
- Typical velocities ~ 100 m/s (fastest rockets ~ 104 m/s)
- Relativity (Special and General) are important for objects moving very fast or very massive
- Speeds near c = 108 m/s
- Protons, Neutrons inside nuclei have very high energies
- Important for motions of galaxies at large fractions of c
- Strong effects of gravity -- black holes
- Quantum Mechanics crucial to understand the very small units from which matter is made
- Typical sizes: Atoms, Nuclei, … ( ~ 10-10 - 10-14 m )