A study of the rich literature on Einstein’s theory of relativity shows that it is a
- theory about physicists
rather than a
- theory about physics.
This difference is expressed by Einstein’s use of the term Principle rather than Law to express his basic assumptions:
- Principle of Relativity
- Principle of Equivalence.
The Principle of Relativity prescribes that physicists using different inertial systems must coordinate their observations according to the Lorentz transformation.
The Principle of Euivalence prescribes that physicists must consider inertial mass to be equal to gravitational mass.
These principles are to be compared with Newton’s Law
connecting mass , acceleration (motion) and gravitational force , which speaks about physics and not about physicists.
The difference is the same as that between a bus and its bus driver: The Law of a Bus is to accelerate when the accelerator is pressed, while the Principle of a Bus Driver is to be sober at work.
Einstein’s theory of relativity is thus not a theory about physics (the bus) but about physicists (bus drivers). This is further evidenced by the fact that the code words in relativity theory are
- speed of light
- time dilation
- space contraction