Reference frames are the different positions (of space, time, speed etc.) in which we can observe any phenomenon or physical event.
We must notice as base of this study that any phenomenon from different positions observed is always the same one, that is to say, invariable in its properties and characteristics. However our observation can be different according to the position that we take.
This way for example:
--If we are located on the moon, we will see that all the other astros seem to rotate around the moon.
--If we are located on the earth, we will see equally that all the astros seem to rotate around the earth.
--If we go for a highway and we go increasing the speed, the kilometres will seem to us shorter.
--If we observe the moon at first sight and later on we look at it through a telescope, we will find that the moon seem has increased of volume.
--If we are located in an embankment and we see pass a train whistling, we will find that when the train comes closer to us, its sound seem to be of more frequency and when the train goes going away its sound seem to be lees frequency.
All these examples and all the other ones that we can put on, show us in one hand that physical phenomena are invariables, and on the other hand, different observation frames exist and each one of them could give us a particular and inexact vision of these phenomena.
And so that the science is, to find the appropriate formula for each reference frame by means of which we can obtain the exact measure of the event.
Therefore the appropriate procedure will be:
1) To obtain the observation
2) To find the appropriate formula to come closer to the reality of the phenomenon
3) And after understanding the observed physical phenomenon, to check that we have applied the appropriate formulas.
Therefore, with relationship to the reference frames we should have in mind that:
--The physical phenomena are always invariable in its property and characteristics.
-- Its observation can be different according to the taken reference frame.
However, scientific as Einstein subject all the physical creativity of the universe to the characteristics of the human being observation. Everything changes according to the human observation. That is to say, we have become in the centre of the universe again, where everything rotates to our surroundings and around our mental capacity of observation.
* Another consideration to take in mind is the different degrees in the qualification of the reference frames, question that is not considered in the transformation of Galileo neither in the studies of Einstein.
In the views of Galileo and Einstein the motion is consider as simple circumstance without considering the cause of this movements.
But this is not this way, and all motion has as principle and condition to the force that produces it, and in fact, the necessity of all force to lean on in a reference frame or field to exercise its influence is what conditions that all motion has attributed an initial reference frame where this motion is supported.
In this case I would define to the initial reference frames as source of emission of the motion or development frame of the motion, still to risk that this emission source is also in movement as usually it happens.
Because well, the emission source should be the main frame of adjustment of the motions, question that very often forgets, reaching conclusions so not very fortunate, as those that end up in the theory of the relativity when studying the speed of light.