Time Dilation & Length Contraction

  In the last post about special relativity, we saw that the speed of light is always a constant everywhere and anywhere in the whole universe.

Now go back to the years of your fourth standard and bring back this simple equation from the treasures of your memory,  

speed = distance/time

And you already know that the speed of light is forever constant, which means that both time and distance have to change for different positions in space and time.

This is what brings us to our point- Time changes and the effect is called Time Dilation, distance changes and the effect is called Length Contraction.

Time dilation says that time moves slower for objects that move faster (inversely proportional). So, a person on a spaceship travelling at the speed of light will age much slower than someone travelling at normal speeds. (This is how Flash reversed time in Snyder's Justice League By travelling at more than the speed of light, he did not just slow time but actually reversed time.)

The length of any object in a moving frame will appear smaller in the direction of motion, or contracted. Thus, the length is maximum in the frame in which the object is at rest (called the proper frame). This is called  Length Contraction.

This gif, courtesy to https://www.physicsclassroom.com/mmedia/specrel , depicts it perfectly:

Fig 1: Object moving at 10% the speed of light

Fig 2: Object moving at 99% the speed of light

Fig 3: Object moving at 99.99% the speed of light