# 6.gravitation theory

**<The Detail of This Chapter.pdf>**

The stage of gravitation: from the
sun to the cosmos

### 1.Why Newton's gravitation theory is wrong?

### 2.The principle of equivalent and its physical
consequences

### 3.How to describe gravitation theory with the principle
of equivalent?

<Euclid geometry->non-Euclid geometry->Riemann geometry>

The fifths axiom: why a pure lines constitution can
determine angle? or if we can determine angle from a pure lines constitution,
then such a stipulation must be an independent axiom!

To avoid Euclid's physical style of studying geometry,
(such style is usually be limited by our intuition easily ) we use some kind of
mathematical representation of geometry object: analytic geometry.

Since point is the most fundamental geometry object, then the metric-a
function that determine the distance between two points, is the most
fundamental character of a specific geometry, of course, what is named distance in the definition of matric must be realizable in the specific
geometry.

Analytic geometry's primary method which representing
geometry object is using numbers to mark a point, that means we must have a set
of stipulation to distinguish points. So we need coordinate system.

A
coordinate system: a set of stipulation that mark
points.

1.the simplest coordinate system is Descartes coordinate
system for Euclid space.

2.

then, we need an algebraic structure to gauge