The Theory of General Relativity is a generalization of Theory of Restricted Relativity, by Albert Einstein, but goes beyond this, taking into account the acceleration of bodies. Therefore, General Relativity is valid for non-inertial references, that is, that have acceleration.
With the restricted relativity, Einstein proved that physical phenomena happen from formdifferent for observers who move with speedsrelativeconstants and that the speed of light it is the same for all these observers. In addition, a equivalence in between time and space. In practical terms, this theory indicates that events that occur simultaneously to an observer can be asynchronous to another. For example: the duration of an event, such as the fall of a body, when measured by a person on planet Earth, may be different if measured by an external observer that moves with a speed comparable to the speed of the light.
Equivalence Principle
THE General Relativity, in turn, is based on the PrinciplegivesEquivalence. This principle indicates that, through an experiment carried out
locally, it is not possible to say whether the acceleration suffered by a body is due to gravity or the application of a strengthexternal of a nature other than gravitational, as their effects will be similar. Imagine the following situation: a person drops an object under the action of the Earth's gravitational field (this object will fall with an acceleration of approximately 9.8 m/s²). This will also happen if an object is dropped inside a spaceship accelerating vertically upwards at 9.8 m/s², without the influence of any gravitational field. Thus, it will not be possible to say whether the object's fall occurred due to a gravitational field or due to its own inertia.one of the big consequences of PrinciplegivesEquivalence is that even if a region of space is accelerated by the application of a strength, if at that location there is a gravitational field that cancels out this acceleration, the observer noit will be able to discern whether or not a inertial frame (with constant speed).
Gravity and the geometry of space and time
Einstein went even further and managed to describe, through General Relativity, the phenomenon of gravity as a change at geometryofspace, a curvature in its shape. Big onespastas they are capable of distorting space and, consequently, time. Since the light it propagates through space, being curved, it will take different times for observers who find themselves in regions with different gravitational accelerations.
despite being called theory, several experimental observations have already confirmed the validity of the Theory of Relativity. One of the most recurrent experiments is the phenomenon of lensgravitational: when light propagates in regions of space highly distorted by great masses, your pathécurved. In this way, it is possible that the images of some stars appear repeated or still blurry in the images taken by telescopes and radio telescopes. The discovery of this phenomenon has made it possible, in recent years, to correct these images.
By Rafael Hellerbrock
Graduated in Physics
Source: Brazil School - https://brasilescola.uol.com.br/fisica/teoria-relatividade-geral.htm