# What is relativity?

The most famous equation on planet Earth “E=mc2 “ given by one of the greatest minds Albert Einstein is known by everyone regardless of his day-to-day chores. However to break the bubble this equation barely scratches the surface of what relativity actually is.

In the years 1905 and 1915 Einstein published two scientific papers that shook the very core on which Physics stood. It was all the buzz back then as it had shredded Newtonian Laws to pieces. It was like a new chapter in the face of the world, however, it was not recognized back then.

‘Why?’ you ask. Well, because the paper was so ahead of its time that even the best of the physicists could not wrap their mind around it or maybe they were scared to come out of their “comfort zone” that Newton had created.

Anyways, the two papers dealt with the phenomena of ‘Special Relativity’ and ‘General Relativity’.

The former dealt with the facts of the speed of light (i.e, 300000 km/s) being absolute. This meant that even if you were in a car travelling at say 100k/hr and emit a ray of light your own speed would have no effect on the speed of light. To put it even more simply the speed of light was constant no matter what.

The one on General Relativity is slightly more complicated though it still talks about the governing of physical laws.

It is common knowledge that Newton gave us the law of gravitation which states that any two bodies in the universe will attract each other with some force depending upon their respective masses and how far apart they were placed.

Einstein however not quite satisfied with this he wished to understand “why gravitation worked?” “Why would two bodies attract each other?” Like what all physicists do he made up a story (well he did give us a quite mathematically sound proof) about why Mother Nature behaves as she does.

He introduced the concept of the space-time continuum (phew! quite some big words there). Imagine a rubber sheet on which you are pulling from all sides so that the sheet is taught. Well there you have it that is the fabric of space-time. Now what Einstein proposed was that let us consider a very massive and heavy object (perhaps the Sun or heavenly body for that matter) it will create a distortion in the space-time continuum. Again to visualize what is going on place a heavy metal ball on the sheet you will notice that it bulges down on the rubber sheet.

This fact that heavenly bodies can distort the space around them was the central piece to his theory of relativity. It shattered age old facts like light can only travel in straight lines because it was experimentally verified that light coming from the Sun bent a little while reaching us.

Another interesting feature of the theory was that mass and time were relative. Both have very similar equations as you can see:

However this means that the velocity at which you travel changes your mass, the fast you got the more mass gain and the slower time is for you. Although the reason you gain mass by running on the treadmill is not because of this. This feature cannot be experienced by us because we rarely ever travel at speeds that are even close to the speed of light. Even the fastest rocket that man can build is nowhere near the speed of light hence the effects of mass loss or time stretching are unnoticeable for our day-to-day lives. However these have been verified by using noticing time differences on atomic clocks taken up to Space than those kept on Earth.

All-in-all relativity has marked a new phase in the world and there is no turning back now.

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