25 Nov 2015

Albert Einstein's 'Theory Of General Relativity' Turns 100!

An apple fell down to the ground, and Newton hit gold on gravity. While it was definitely an important observation, after a great deal of study, physicists could mark out the limitations and obscurity in Newton's theory. Newton's law stated that bodies tend to attract each other, and more heavier the bodies, the greater the force of attraction. And using this theory scientists were able to calculate the orbits of planets explicitly - except for Mercury. By the end of 19th century, it was pretty much clear that his theories were not applicable to all scenarios. And here's where Albert Einstein found seed to sprout a theory that was to revolutionize physics forever.

albert einstein

It was on November 25, 1915, when Einstein had first furnished an equation of general relativity which significantly changed physicists' perception of the universe, and some of the challenges that cropped from the equation are unresolved till date. It was able to reconstruct Newton's theory on gravity and repair the discrepancies it held, including the calculation of Mercury's orbit.

Einstein had earlier demonstrated that the speed of light remains same for everybody, and that space and time are the variables experienced differently by different people. Einstein in the theory of special relativity submitted in 1905, mentioned that space formed three of the dimensions - length, breadth and depth, while time forms the fourth dimension. This formed the framework of spacetime.

albert einstein theory of relativity

Einstein's proposition of gravity involved matter interacting with space and time (or "spacetime"), where matter itself can distort spacetime by moving within it. What Newton theorized about the Earth's orbit was that since our planet was attracted by the Sun, it's path was distorted by the constant pull resulting in an elliptical orbit. So as per the Newtonian perception, Earth is not a free entity. Einstein on the other hand stated that Earth is indeed moving freely along an analogue of a straight line, but through a curved spacetime distorted due to the huge mass of the Sun.

It was in 1919 when astronomers first realized the Sun's effect of bending starlight. Since then, the theory of general relativity and the predictions following it have been confirmed on multiple occasions. The theory reveals the evolution of the universe - its Big Bang origin and its expansion.

But the theory, with extensive mathematical usage, still has its own set of limitations. The equations cannot explain what physicists refer to as singularities (mystery zones) like black holes, or for that matter Bing Bang itself. They believe that any attempt to solve these singularities would require them to blend general relativity theory with quantum mechanics, a branch of physics that deals with the behaviour of the subatomic world.

interstellar spacetime

General relativity has even inspired many science-fiction Hollywood movies including Christopher Nolan's brilliant Interstellar (2014).

There's also a beautiful infographic called '12 Things To Know About Relativity' which you can view in Space.

Image Sourced from - Space.com | Edlibre | The Spirit Science


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3 years ago
Nice overview

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