**Theoretical physics** . It is the set of knowledge consistent with certain real events. Branch of Physics whose starting point and reference are knowledge consistent with certain real facts of experimentation.

## Summary

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- 1 Need
- 2 Problems
- 3 Model
- 4 Unique principle
- 1 Formula of the principle
- 2 Mathematical expression

- 5 Reference systems
- 6 Principle of Galileo
- 1 Galilean Reference System

- 7 See also
- 8 Source

## Need

Every experiment waits for the theory to explain it. The facts await an explanation. Real facts provide knowledge that man uses as a starting point or fundamental propositions, which we call principles, to which it is necessary to give them a mathematical formulation, the language from which the conclusions, inferences, and implications that result are obtained. in predictions about results of new observations and experiments .

These conclusions, inferences, and implications are the body of a physical theory , but the cornerstone of theoretical scientific knowledge is the, or, the fundamental principles. Physical principles constitute the initial propositions of deductive knowledge and, in themselves, cannot be deduced from other propositions.

These principles must be obtained through an arduous inductive process, which requires knowledge, experience and a special talent that allows the connection of apparently disconnected events. Men in all their historical evolution raised principles and developed theories.

## problems

Theoretical Physics faces two typical problems:

Albert Einstein

- The expression of the observed physical laws in the form of quantitative relations .
- The application of mathematical methods to the formulation of new physical laws that achieve their highest culmination in the prediction of facts and laws not yet revealed by experience.

## Model

The ideas that guided and lead to a certain Geometry , model of a certain Physics . The first expressed the assumption that asking what the geometry of a world was was equivalent to asking what the physics of that world was, the second using the assumption that geometry can be expressed using numerical quantitative relationships. Then certain quantitative numerical relations express a certain geometry and this in turn is equivalent to a certain physics.

## Unique principle

Vector analysis is the appropriate mathematical formulism or model to expose and solve the theory of the electromagnetic field because the specific formulism of vector analysis expresses essential characteristics of the state of an electromagnetic field is that when studying the all-important problem of motion, mathematical theory first arises which responds to the problem raised.

There is no difference between playing ball on land, on a boat, or on an airplane, when the movement of these means of transportation is not noticed. This is so, because the difference does not exist, with the only condition that the ship or the plane move at a constant speed, that is, uniformly. With the eyes closed and the ears covered, it is impossible to distinguish rest from uniform movement whatever the speed with which it is performed.

This is indisputably demonstrating the phenomena and processes that take place in bodies that move uniformly, they follow the same laws as if they occurred in bodies at rest. This statement is called Galileo’s principle of relativity.

### Formula of the beginning

- The laws of nature pass in the same way, regardless of the state of rest or uniform movement of the observer’s transport.

### Mathematic expression

If you are traveling in a balloon or a train and you see that another train or another balloon changes position with respect to ours, we have no means of knowing which of the two balloons or the two trains is in motion. If a point moves and we call the starting point x0 and x1 the arrival point, the first question will be at what time this distance was traveled and we can represent it in the form x1 – x0 = vt where the number v is the amount of times the unit of measurement t was repeated.

If the point has not moved then we would have x1 – x0 = 0 so we can write x1 – vt = x1 – 0. Here 0 can represent a point considered at rest and vt, one in uniform motion.

## Reference systems

To express the laws of nature a Reference System is needed . A reference system is nothing more than a coordinate system that allows expressing a certain principle.

If any reference system is chosen up to the simplest principles, they become cumbersome to express. That is why a coordinate system is chosen whose formulaism expresses as faithfully as possible the principle from which it starts.

## Galileo’s principle

The principle that the laws of nature are the same for both the observer whose transport is at rest, and the one whose transport moves uniformly “is commonly called by that name Galileo’s Principle and is expressed by a system system Galilean reference.

### Galilean Reference System

If in a reference system a point moves in such a way that it does it in the same way both for a point considered at rest, as for a point considered in uniform movement, the system is Galilean