One of the most ground-breaking theories in physics which led us to the understanding of universe that we know of now is Time dilation. But, before we move on to that, lets brush up with some of our basic concepts. So, we all have studied in physics about Newtonian relativity which states that the speed of any body is measured relative to the observer’s frame of reference. In simple words, If you are sitting in a moving car with your friend, your friend appears to be stationary to you as you both are moving with same speed in same direction viz, you both are in same frame of reference. But, if a guy who is standing on the road sees you he will record your speed as the speed of the car. Also, if you throw a ball from this moving car, at a speed , say 20 and car is at speed say 40. Then in ideal case, the ball will have total speed of 60 when thrown.

Now, lets apply similar logic with a slightly different scenario. You are in a stationery car, and you start its headlights and the exact speed of light is measured and recorded. Now, the car is moved at a speed of say, 80 km/hr and the headlights are blinked and again the speed is measured. Now, Newton’s theory says that the speed of light that would be measured must be addition of speed of light and speed of car (Which is of course very minute as compared to speed of light) But, the results say otherwise. The speed of light remains constant and not even minute increase in speed is recorded. This concludes that speed of light is constant irrespective of frame of reference in which it moves.

The question is, does Time depend on the frame of reference of the observer? Is time different for people in different frames of references? And surprisingly enough, the answer is Yes. The Time passes differently depending upon your frame of reference. If you are sitting at rest. The time passes normally as your speed is zero. But, if you are moving at a certain speed, the time will pass slower than it will at rest. This thing that time passing differently for each person depending on their frame of reference is called Time Dilation. So, why don’t we observe it? Because it is minute when compared to the human speeds. To observe measurable time dilation, one would have to go close to the speed of light. This theory was put forth by Albert Einstein and then was worked upon by many other physicist all of them leading to prove it right. Continue reading “Time Dilation”