Eventually, he realised that he needed to extend the description of spacetime and its structure beyond the rules of classical geometry, where parallel lines never meet and the sum of a triangle’s angles is 180°.Īrtistic view of massive bodies bending the structure of spacetime. In 1907, Einstein started working towards a theory that would encompass gravity, too, but he could not find a way to address it in the ‘flat’ spacetime of special relativity.
In addition, they are not absolute, but can be seen to shrink or dilate according to the observer’s speed. In 1905, he had developed his theory of special relativity, showing that space and time are not independent but intimately intertwined in the four-dimensional continuum of spacetime. However, this was not the main reason that Einstein pursued a new theory of gravity. Newton's theory could not fully account for the amount of this precession, up to the point that astronomers speculated about the existence of an unseen planet within the orbit of Mercury. After each revolution, the planet's closest point to the Sun, or perihelion, appeared to occur at a slightly different position – this phenomenon is known as precession. While Newton's theory is still a great approximation to address gravity in a variety of situations, especially in our daily life, Einstein's novel approach achieved a more complete account of gravity's behaviour, especially in extreme cases.Īt the turn of the twentieth century, the only physical problem that remained unexplained within Newton's gravity was a tiny shift in Mercury's orbit. It is directly proportional to the product of their masses and inversely proportional to the square of their distance. In Newton's framework, gravity is a long-range attractive force, acting between any two massive objects. Prior to general relativity, the leading theory of gravity was Isaac Newton's law of universal gravitation, which unified the description of moving massive bodies both on Earth and in the Solar System. A revolutionary approach at the time, general relativity remains to date the best physical theory to describe gravity, particularly on cosmic scales.Īlbert Einstein in 1921. November 2015 marked a notable anniversary in the history of physics: one hundred years before, Albert Einstein presented his general theory of relativity, in the form of four papers, to the Prussian Academy of Sciences in Berlin on 4, 11, 18 and 25 November 1915.
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