Status at this point for Einstein (and us)
Classical physics a la Newton:
- Motion described in time and space
- Newton’s Laws: 1. Inertia: Objects move in straight lines if there are no forces 2. F= Ma 3. Action/Reaction (Conservation of Momentum)
- Forces come from other bodies (e.g., gravity)
- Gravity is “action at a distance”
- Remarkable fact: Inertial Mass = Gravitational Mass
Conceptual Changes in Special Relativity
- Time and Space related - Space-time
- Speed Limit = c = velocity of light
- Must replace “action at a distance” by new laws for gravity
- Mass redefined! Changes as function of velocity
- What to do??