Here we show that the Schwarzschild Metric can be easily obtained starting from closed volumes instead of the mass concept.
This demonstration does not require complex tensor manipulations as in the traditional method.

This webpage is part of the website
http://www.mass-gravity.com
To understand the demonstration, it is necessary to read the whole theory.

Minkowski Metric

The expression of the Minkowski Metric, in spherical coordinates, is:

The Schwarzschild Metric refers to a static object with a spherical symmetry.
It is built from a Minkowski Metric, in spherical coordinates, with two unknown functions: A(r) and B(r) :

Remembering that the Minkowski Equation follows the Lorentz Invariance, we know that the only way to get this invariance
is to set A(r) = 1/B(r).

From a mathematical point of view, we get the same result developing and simplifying EFE with correct parameters.
Details of calculations are described in many articles and books concerning General Relativity.
This conducts to the following equality:

Notes: Some authors prefer writing A(r)B(r) = K with K=c^{2}.
In that case, the term c^{2} must be excluded from the Minkowski Metric, equation 1.
However, in both cases, result is identical.
On the other hand, in order to simplify equations, some Authors also replace c and G by 1.
To avoid inconsistent expressions, we do not follow this rule in this webpage because a simple number, "1" in this case,
does not have a dimensional quantity like c^{2} or G, [L^{2}/T^{2}] or [L^{3}/MT^{2}] respectively.

Schwarzschild Metric

To calculate the Schwarzschild Metric, we can start with the figure of the main text concerning
a convex curvature of spacetime (fig. 1):

where :

dr_{out} is an elementary differential radial variation outside of any mass,

dr_{in} is an elementary differential radial variation inside a Schwarzschild space,

r is the point of measurement.

As in the Newton Law webpage, we have:

where:

e is a coefficient of the increase of spacetime curvature at distance r,

DR is the initial curvature of spacetime produced by the closed volume,

The order of magnitude of e being 10E-39, we can use the first order approximation:

Since e is a simple coefficient, we can calculate the relation between two
differential elementary radius dr_{out} and dr_{in}, out and in a gravitational field:

Since e << 1, the equivalent formula is:

or, elevating in square:

Developing the denominator (1 - e)^{2} = 1 - 2e +
e^{2} and ignoring the last term e^{2},
we obtain:

This result is nothing but the radial component of the Schwarzschild Metric, that is to say the function A(r)
of dr^{2} in equation 2.
The calculation of B(r) is immediate using equation 3:

So, equation 2 becomes:

In the Newton Law webpage, we have obtained the following result: DR = KM
(equ. 13), where K = G/c^{2} (equ. 20). So, equation 5 can be rewritten as:

Finally, porting this expression in equation 12 gives:

As we have here demonstrated,

The proposed theory, based on closed
volumes, gives an easy and consistent
explanation of the Schwarzschild Metric.