From the relative existence of electromagnetic field to its connection with the gravitational field

The present document starts from the relative existence of the electromagnetic field, reaching through mental experiments to its connection with the gravitational field, without the necessity to resort to other space - time dimensions or supplementary "exotic" particles. The final conclusion is that the field "electro-gravitational" and electromagnetic field with accelerated source are two different manifestations of the same single field dynamic. Whilst demonstrating why there are light sources with "flee" towards the red or blue of the light spectrum.