Einsteins's Theory of General Relativity

August 30th, 2020

By: Haris Ahmad

In 1905, Einstein published his special theory of relativity which was vastly criticized and people had started mocking him as they thought that, how can such a person explain gravity better than Newton did in his laws? However, a decade later, in 1916, Einstein published the General theory of relativity which comprehensively described the geometry of space.  

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It was this theory that was going to change our perception of gravity itself. For decades we thought that the universe was ruled by Euclidian geometry which we learn in schools. Euclidian geometry suggests things like; parallel lines can never intersect, and the angles of a triangle add up to 180 degrees, and so on. This, however, was not the case in General relativity. On the contrary, general relativity showed that just like you can distort things drawn on a piece of paper by bending it, space can also be distorted due to bending around massive objects.  

Moreover, bending a two-dimensional piece of paper results in it being wrapped around a third spatial dimension and similarly, the bending of space around massive objects results in the third dimension being wrapped around a fourth spatial dimension according to the distribution of all matter around the universe, since mass is the property which causes the bending of space-time fabric. This fourth spatial dimension is impossible for us humans to comprehend because we are limited to only being able to comprehend until the third dimension.  

However, we humans still use resemblances to represent the fabric of space in a two-dimensional representation of the third dimension showing that the fabric of space-time is bent around massive celestial bodies. This way of representation is not much accurate but it’s simply the best we can do to understand this phenomenon. This concludes by bringing forward the idea that the universe is non-Euclidian and even parallel lines can indeed intersect if they move through curved space-time. 

 

https://physics.stackexchange.com/questions/309369/the-fabric-of-space-time

Einstein calls this work, the general theory of relativity due to the fact that this applies to all reference frames which means that it can apply to any acceleration (a= any value). The general theory of relativity is an enhancement to Newton’s law of relativity due to the fact that Newton explains the effects of the gravitational force but he never explains what gravity itself is, which Einstein did.   

Hence, due to Einstein’s general theory of relativity, we can now deduce that gravity is the bending and warping of the fabric of space-time. An example of this is how a dense ball bends the surface of a trampoline.  

Therefore, this suggests why less massive objects tend to fall towards more massive objects and hence, this is what explains the dynamics of the universe such as, why the planets in the Solar system orbit the Sun. Furthermore, the idea of general relativity also deduces the fact that space and time are not separate but instead, they shape the interlinked four-dimensional space-time fabric. Nevertheless, matter obeys space-time to know how to move whereas space-time obeys matter to know how to curve.  

The theory of general relativity has been confirmed by countless experiments of which one, made Einstein famous overnight. It was the experiment conducted on the event of a total Solar eclipse in 1919 which proved that light from distant objects is bent by the gravity of massive objects which in this experiment was our very own parent star, the Sun; whereby the blocking of the Sun's light allowed us to directly observe the light from the star that was behind the Sun which appeared to be in a different location than it normally is. 

  

https://www.pinterest.com/pin/84301824259043502/

In addition, the phenomenon of gravitational lensing also confirms the general theory of relativity in which light from celestial objects behind extremely dense objects such as black holes is bent in such a way, that it results in multiple images of the object seen around the black hole.

  

https://astronomy.com/magazine/2012/11/diy-gravitational-lensing