Special Relativity- An Abstract Explanation - Arhant Bararia

Early scientific studies focused on the things one might see or experience in everyday life.  Many philosophers (so called scientists) like Galileo, Isaac Newton etc. gave their theories about how balls rolled down the inclined surface and the how apple falls. Newton came up with handful of mathematical equations, he explained the motion of earth around the sun and the simple motion on earth.

“Newton brought a wealth of physical phenomena within a single theoretical framework” –Brian Greene

Now everyone knew how motion took place and motion of a body is now more predictable.

Now suppose you are reading this article sitting in a moving car or a train. Now if I may ask, are you stationary? Your answer will be no ‘cause the car (or train) is moving. Now if I bring my own car beside yours with same velocity as yours, then I ask same question again, are you stationary? Your answer will be still no because you still see the trees moving past to you but what is your state of motion with respect to me? Are you still moving?

This was a big hurdle in the way of Isaac Newton because now people knew that things are moving but with respect to what? Newton realized that this key question had to be answered because without understanding the space and time, his equations would prove meaningless.

Later on he described Absolute Space and Time as immutable entities that provided universe with a rigid and unchangeable arena. But is this true?

If you want to know how he explained the concept of absolute space and time click here

We’ve been playing with magnets since our childhood and we all know that like poles repel and unlike poles attract. The great physicist Michael Faraday studied the magnetism and electricity and concluded that these (magnetism and electricity) are interrelated with each other thus known as Electromagnetism. Michael Faraday did a great work and based upon his works Sir James Clerk Maxwell gave 4 powerful equations. Somehow these equations found that charges or disturbances to electromagnetic field travel in a wave like manner and with a speed of 3 X 10⁸ m/sec (or 670 million miles per hour), and experiments found out that light also travels with this same speed (i.e. 3 X 10⁸ m/s), so, Maxwell proposed that light is just an electromagnetic wave and his equations gives the speed of light.

Now again that same question 3X10⁸ m/s but with respect to what? According to newton the answer will be that absolute space (which is rigid and unchangeable).  But then according to him if we chase a beam of light then it’s speed decreases (<3X10⁸m/s) and if we move toward it’s speed will increase (>3X10⁸m/s).

It’s still not true, experiments found that the speed of light is constant i.e. this no. 3x10⁸ is a constant no. that does not change for anyone.

 To create an analogy let’s take an example: Usain Bolt as a lover of speed made a car whose maximum speed is 500 million miles/hour. He decided to race with the ray of light (with speed 670 million miles/hour), his friend John started the countdown from 10. As he speaks 0,he fires a ray of light and Usain and his supercar streak off .After an hour John found that light has covered 670 million miles and Usain has just crossed 500 million. So John concludes that light is speeding from Usain at 170 million miles/hour. According to Newton, Usain will agree with John’s conclusion.

But when Usain returns he doesn’t agree at all. Instead he dejectedly claims that no matter ho hard he pushed the accelerator, he saw the light speed away at 670 million miles/hour.

But Why???

Albert Einstein entered the story with very logical reason that experimenters who are moving relative to each other, like Usain and John, will not find identical values for measurements of distances and durations.            Is this the end of this story? NO

Now Usain after losing from light was going back to his town driving his car with 50 miles/hour in north direction. Then he takes the way to north-east, now his velocity in north direction is less than 50 miles/hr. This simple idea allows us to capture the core insight of special relativity.

There are 2 kinds of motion, One is that objects move through space (3- Co-ordinates x,y,z) but there is another kind of motion ,Objects also move through time. Your wall clock or your wrist watch is constantly telling you that you’re moving through time, relentlessly moving from one second to the next. Now if you see a car parked in the street, that car is constantly is moving through time, but if the car speeds away in space it’s speed in  time dimension  will decrease just like Usain’s speed (50 miles/hour) from north direction. 

Einstein discovered that these 2 motions are complementary. In his special relatively he declared a similar law for motion, “The combined speed of any object’s motion through space and its motion through time is precisely equal the speed of light.”

But you may be thinking that nothing can go faster than speed of light but my friend that’s just through space. So now if you are stationary you are actually moving with light speed in time .  😎 

The whole speed of light is just through space i.e. light doesn’t pass through time.

If a photon (particle of light) checks his wrist watch, he will not see the time passing because light doesn’t age. Just driving due east leaves no motion in north direction, just like that moving through space with light speed leaves no motion for travelling through time. And yeah the time stops!

Speed of light is 3X10⁸ relative to anything and everything.

And this is the theory of special relativity.

more about the relative motion here .