Friday, 26 April 2013

Albert Einstein, "Who is that guy" & Theory Of Relativity Simplified

Albert Einstein- How do we know him?
We all know who Albert Einstein is. When asked about him, we generally have only one answer, “He was a great scientist, probably the greatest theoretical physicist we have ever witnessed”, or some may say “He was the one who gave us the equation ‘E=mc²’, for which he became very famous”. But was that all?
Albert Einstein was born on 14 March 1879 in Württemberg, Germany, to a Jewish family. He was not a brilliant student in school as he felt very uncomfortable to study history and remember dates, but he was very interested in science. Later, he moved to Switzerland to attain a teaching diploma in Physics and Mathematics. He then received his doctorate and in due time, he published the most revolutionizing papers on physics, which changed the shape of Astronomical physics forever.
Einstein was a theoretical physicist; a person who finds or creates theories based on previously or newly found observations. His most noted works, for which is widely known is regarding light (the photoelectric effect), matter (his famous equation e=mc², which is energy=mass times the square of speed of light) and his most famous work for which he was awarded the Nobel Prize is on his general theory of relativity. So let’s try to put some light on it and know why he was so famous.
So what is the general theory of relativity or simply, general relativity? In simpler words, Einstein gave an absolutely new definition of gravity, and explained that why gravitational field of high masses bends light. Till then we knew that light doesn’t bend, but it gets reflected from shining surfaces, until he gave the theory of relativity. General relativity states that “if a light ray passes through the path of the sun (heavenly body); you would actually see it shift, just a little bit because of the heavy gravity of the sun”. This concept seems impossible to believe with the classical theories of space and time, until he gave a new term which unites both space and time as one, called the spacetime continuum, which changed the concept of gravity which we now study in physics.
To know relativity, we first need to know about spacetime. Consider millions of horizontal and vertical lines weaved together to form a fabric, with the lines representing time and space respectively. This one fabric is spacetime, which is laid throughout the universe. And this spacetime is the new definition of gravity. Gravity isn’t just a force, it’s the depth formed by a heavy mass on this fabric, which causes objects like satellites and asteroids to revolve around it. For instance; if you stretch a big rectangular elastic blanket from its four corners and drop a heavy mass (or a ball) in its centre, you will observe that it creates a depth on the blanket. And now on the blanket, if you gently keep a mass of comparatively lesser than the heavier mass, you will observe that the lighter mass revolves around the heavier mass for a period of time. This concept of the blanket or fabric is somewhat known as spacetime, in terms of gravity in which gravity is directly proportional to the depth it creates in spacetime. So in simple words, the more depth a mass creates on spacetime, the more will be its gravitational force to attract other masses.

Now imagine this blanket is laid all across the universe, and masses heavy as stars, suns and especially black holes are kept on it! Imagine the depth they would create on spacetime, and the gravitational force caused by them. This immense gravitational force, caused by the depth created on spacetime causes light to bend when it passes through the sun’s or the black hole’s path. Now you may know as you have heard as why light cannot escape black holes. The immense mass of a black hole (heaviest mass known till yet) causes an infinitely large depth on spacetime, which doesn’t allow light to pass through it. This also creates an idea as why the heavenly bodies in space are suspended at their respective places, as due to their respective depths in spacetime. This theory of relativity made Einstein the most famous man on earth and was awarded the Nobel, when his theory was experimentally proved by Arthur Arrington during a solar eclipse, that light bends near the sun when it comes a star farther than it.

  So this is what we call, the general relativity, explained in simpler words. And this is how we know Albert Einstein. Einstein wasn’t just a physicist; he was the greatest physicist of all time.
-     Maharshi Chakravortee

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