Posts

Choice of the Lagrangian density for the gravitational field.

Image
 Ruslan Sharipov.   1 ... 10 11 12 ... ru The Lagrangian L is included in the action integral, which we considered in the previous post " The Lagrangian approach to deriving the equations of gravity in the new theory ". The Lagrangian L itself is expressed in the form of a three-dimensional integral of the Lagrangian density. As we see from these formulas, the Lagrangian density is the sum of two terms — the Lagrangian density of the gravitational field and the Lagrangian density of matter. The Lagrangian density of matter describes the dynamics of matter. It depends on a specific type of matter that can be cosmic dust, gas, liquid, solid, or even dark matter. We will leave the choice of Lagrangian density of matter for later. Now let's consider the choice of the Lagrangian density for the gravitational field. The dynamic variables of the gravitational field in the new theory are a three-dimensional metric and a scalar function denoted by the letter g with two zeros.

Lagrangian approach to deriving the gravity equations in the new theory.

Image
 Ruslan Sharipov   1 ... 9 10 11 ... ru The Lagrangian approach to deriving various equations is associated with the name of Joseph Louis Lagrange. Detailed information about him can be found in Wikipedia . In mechanics and in physics his name is associated with the so-called "least action principle". According to this principle, the evolution of a physical system occurs in such a way that some integral over time turns out to take the smallest possible value. This integral is called the action integral. It is usually denoted by the letter S. The function L in the integral S is called the Lagrange function or the Lagrangian. In field theories it is itself an integral over spatial variables. In the spatial integral L we see a function denoted by the same letter, but in a calligraphic style. This is the Lagrangian density. It is represented as the sum of two terms: the Lagrangian density of the gravitational field and the Lagrangian density of matter. We will discuss the La
Image
Discussion of the obtained gravity equations. Ruslan A. Sharipov.  1 ... 8 9 10 ... ru   We shall discuss the equations of the gravitational field in the new theory of gravity, which is called « 3D-brane universe model ». I am the author of this theory. Therefore, you will receive first-hand information without any distortion. The gravity equations in the new theory are subdivided into two groups. The equations of the first group have the form They depend on two indices i and j . When these indices are rearranged, the equations do not change. Therefore, different equations are obtained only for the following values of the indices: (i=1,j=1), (i=1,j=2), (i=1,j=3), (i=2,j=2), (i=2,j=3), (i=3,j=3). This means that the total number of different equations in the first group is 6. The second group of gravity equations in the new theory contains only one equation. As a result, the total number of the gravity equations in the new theor
Image
Einstein's equation and consequences from it in the new theory. Ruslan A. Sharipov. 1 ... 7 8 9 ... ru   Einstein's equation was written by him in 1915. A historical essay about it can be found in Wikipedia . It captivated and captivates many people with its simplicity and elegance. In Wikipedia you will find this equation written with the plus sign in front of the constant Λ. I wrote it with the minus sign. This is my mistake. It was admitted long time ago in 1997, when I was writing my textbook “ Classical electrodynamics and  theory of relativity .” The Internet in Russia and in the city of Ufa was much less accessible that time than it is now. Also there was no Wikipedia; it appeared only in 2001. It was necessary to go to libraries and rummage through catalogs in search of even older textbooks. But I was lazy. In order not to contradict my textbook, I now write Einstein’s equation with the minus sign in front of Λ. This is not a big problem. It is enough to take the

What we take from Einstein?

Image
  Ruslan A. Sharipov. 1 ... 6 7 8 ... ru   The “3D-brane universe model” is the name of a new non-Einsteinian theory of gravity. This theory is based on criticism and denial of the space-time as a material entity. However, it does not deny all the achievements of Einstein's theory and strives to digest and incorporate everything that is possible from Einstein's theory. In this article we analyze the elements of continuity between the two theories. In Einstein's theory gravity is described by a four-dimensional metric. It can be understood as a 4x4 matrix, which is shown in the figure to the left of the arrow. The components of this matrix depend on coordinates and time. Space-time in the new theory is subdivided into a foliation of 3D-branes. Each of these branes corresponds to one of the moments in the evolution of the real three-dimensional universe. The foliation of 3D-branes determines the choice of special coordinates, which are called

How many speeds of light in the new theory?

Image
Ruslan A. Sharipov.  1 ... 5 6 7 ... ru   The new theory here means the theory of gravity which is called “3D-brane model of the universe.” Light is an electromagnetic wave, and electromagnetism has been studied inside and out. There is only one speed of light in it. It is listed first on our list. The new theory also has one single speed of light. But, besides it, the new theory has several other speed constants. The second constant in our list is the speed of gravitational waves. The third one is the limiting speed for baryonic particles. And the fourth one is the limiting speed for non-baryonic particles. Some clarification is required here. In particle physics, baryons are particles composed of quarks and antiquarks with the baryon number equal to +1 or -1. In astrophysics and in the theory of gravity, a broader interpretation of this term is used. Baryons or baryonic matter here refers to all visible matter i.e. the matter that can absorb or emit light or ca

Brane time

Image
Brane time.   Ruslan A. Sharipov 1 ... 3 4 5 ... ru   I have already told that in the new theory, which is called the “3D-brane universe model”, there is a dedicated infinite family of 3D-branes (see 3D-branes in the space-time ). It turns the space-time into a 3D-brane foliation. Each brane in this folation corresponds to a specific instant in the evolution of the universe. Only one of the branes corresponds to the current moment, that is, the instant of the present. It is that very brane thatshe has the prototype in the form of the real three-dimensional physical universe in its current state. The remaining branes correspond to past states of the universe that have ceased to exist, and its future states that have not yet formed.   What is a brane time? This is a numerical function that is constant within each brane of the 3D-brane foliation and increases in the direction from the branes of the past to the branes of the future. In addition to this condition, the brane time functi