Written by Ana Luiza Bastos Barbosa Guimarães da Silva

Translated by João Miguel Matzenbacher

   For many years, newtonian theory for gravity was the only theory capable to describe large-scale phenomena, however it has some flaws that put some question markers in the physicists head.
   Only with Einstein’s General Relativity Theory this questions have been answered and a new perception of the universe was proposed (see the fight between Einstein and Newton on the figure 1).

   


Figure 1. Arm wrestling between Einstein and Newton to decide who is the gravity owner


   So lets talk about this long journey, from creation to the evidences of this theory that surprised everyone?

   Well, the General Theory of Relativity was published in 1915, it generalizes the Special Relativity and refines Newton’s law of universal gravitational by introducing a geometric concept of spacetime and relating this to energy and momentum.

   The first success in comprovating this theory was in 1915, when Einstein solved the mercury’s perihelion problem, finding a OSCILLATING TERM in the expression which describes mercury’s orbit, this factor could only be found through the general relativity theory.

    Four years later, Einstein’s theory was experimentally investigated through a solar eclipse which occurred in 19th May, 1919 in the city Sobral located in our Brazil (see figure 2). This event happened to be known as the second success of Einstein’s Theory, when two British expeditions detected light bending when went through a massive object, in this case: Sun.

    But, before this success, Einstein expected that his theory could be proved through the solar eclipse in 21st August, 1914!  Because of that, an expedition led by Erwin Freundlich traveled to Crimea (located in Eastern Europe), where the eclipse would be visible. However, after traveling for two weeks, Germany had declared WAR against Russia and the scientists were ARRESTED on charges of ESPIONAGE.


Figure 2. Albert Einstein statue, located in Sobral, Ceará, Brazil. Despite Einstein had never actually been in the city, it was there that the solar eclipse happened in 1919 was observed. 


   Imagine that! Looking on the bright side, Einstein had a mind blowing insight, he had corrected on of his calculations leading to a more accurate result, predicting a bigger value for the light bending phenomena, which I already said, this was lately proved by the British expedition.

   The third success took until the 1960s to come up, it is the proof of the gravitational redshift, also known as the atomic clock experiment that provides a direct proof of time dilation!

   Nowadays, 100 years later, we have got an absolut success when the first picture of a black hole was released, as we can see in figure 3, leading to a few more steps in science! Not only that but in 14th September, 2015, happened the first direct detection of GRAVITATIONAL WAVES through  Laser Interferometer Gravitational-Wave Observatory (LIGO), originated by the fusion of two black holes, leading to a physics Nobel Price for Reiner Weiss, Kip Thorne and Barry Barish! 

   Of course we have a lot of things to discover, study and detect, but, to finish up this column I will let you with a quote from our master Albert Einstein to inspire you guys who are beginning in science, a young scientist, a student, a curious by the physics: “The important thing is not to stop questioning, curiosity has its own reason for existing”.



Figure 3: Black Hole located in the center of the galaxy called Mesier 87, a region approximately 53 millions light years far from Earth.