Saturday, August 14, 2021

Einstein's general relativity completely revolutionized understanding of the universe

Albert Einstein's theory of general relativity, published in 1915, completely revolutionized science's understanding of the universe.

 It was only confirmed for the first time in 1919, with an experiment carried out during a total eclipse of the Sun in Sobral, Ceará, and Ilha de Príncipe, in the São Tomé and Príncipe archipelago.

 From then on, the then-unknown German physicist became a worldwide celebrity, and was stopped on the street to sign autographs.

 But what exactly is this theory and why was it so revolutionary?

 Until the beginning of the 20th century, physics was governed by the laws of Isaac Newton. The English physicist and mathematician said that gravity was a force caused by the mass of objects and caused them to be attracted towards each other.  The object with more mass attracts more intensely. That's why we keep ourselves on the ground on Earth.  It draws us to its center.  That's why the planets also move around the sun.

 But imagine that the sun suddenly disappeared completely.

 According to Newton's theory, the planets in the Solar System would instantly leave their orbits, as there would no longer be the Sun's gravity pulling them. For him, gravity was an immediate force of action, regardless of the distance between bodies.

 But Einstein encountered a problem: according to his calculations, light was the fastest thing in the universe.  No body with mass reached a speed greater than that of light.  Nor gravity.

 In the ten years he spent thinking about it, between 1905 and 1915, the German physicist created the theory of general relativity.

 He imagined the three dimensions of space and the dimension of time together, as a kind of fabric that surrounds us and which is deformed by the presence of massive celestial bodies, such as planets and stars. These deformations create what we feel as gravity.

 So the Earth and the other planets remain in orbit not because the Sun simply attracts them, as Newton thought.

 For Einstein, this is because the Sun is such a massive star that other bodies follow the curvature it generates in the fabric of spacetime.

 General relativity allowed us to explain from the birth of the Universe to the orbit of planets and black holes.

 To this day, some of his predictions are tested and confirmed by scientists, who are surprised by the accuracy of the German physicist's ideas.

 Because of it, he became one of the most iconic figures in world science.


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