# Rethinking some of Einstein’s Thought Experiments

*Note: this is an excerpt from Introduction to Quantum-Geometry Dynamics 3rd ed*

According to QGD, the inertial mass and the gravitational mass of an object are fundamentally one in the same thing. This equivalence is a fundamental assumption of quantum-geometry dynamics which naturally emerges from its axiom set. In fact there is only one definition of mass: the mass of an object being simply the number of it contains. That number determines not only the effect of gravity but all non-gravitational effect. But while gravitational mass and inertial mass are the same thing, describing a dynamic system requires that we understand an important distinction between gravitational and non-gravitational effects.

Rethinking Some of Einstein's Though Experiments Using QGDThe PDF file can be downloaded here.