Time Dilation

-brought to you by The Spacestellar

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What is Time dilation..??

Why the Newton's laws of Motion is wrong..??

Why does the moving clock ticks slower..??

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First of all, let us understand the word 'Time dilation'. Time Dilation is an event which makes time dilated( to make wider or larger). Technically, Time dilation is a difference in the elapsed time measured by two clocks, either due to them having a velocity relative to each other or by there being a gravitational potential difference between their locations.

Sir Issac Newton

In the year 1686, Sir Issac Newton published his three famous Newton's laws of motion. It all worked well for almost 200 years. But, there was some problem with Newton's laws, these laws worked absolutely well for small velocities experienced on earth, but it predominantly failed for higher velocities, which was noticed by quite a few of them. In 1906, Sir Albert Einstein published his Special Theory of Relativity which completely revolutionized the world of physics. He introduced a different field of physics which was completely unknown at that time. The specialty about Einstein was that he tried to observe the functioning of the world at the light's speed. One of the three consequences of Einstein's Special Relativity is Time Dilation.

Sir Albert Einstein

Firstly, we need to understand that, there exists nothing such as absolute rest or absolute motion. Each and everything moves relative to one another. Even the Earth is in motion with respect to the Sun. Also, the Sun moves around the centre of the Milky Way galaxy. So, there exist no frame of reference with respect to which, one define absolute rest or motion. Imagine, you are standing on ground and your friend is travelling in a car. Therefore, you are at rest and your friend is in motion with respect to the ground's frame. According to the Time dilation, times runs slow for your friend (Here you need to know that, the both the watches or the clocks used by you and your friend is well synchronized and neither they have any damages which make them behave like that). This is how the nature actually behaves and tries to hide it's mysteries. But at such a lower velocity, the Time dilation experienced is negligibly small. Each and everyone of us experience Time dilation on daily bases, but, on a very small scale.

Clock A is at rest(left), Clock B is in motion(right)

Here the clock in S' frame is in motion with respect to S frame. Therefore time moves slow for the clock in the right. Therefore we can say that The Moving Clock ticks slower.

In this Time dilation equation, we observe that when 'v' is negligibly small compared to 'c', the square-root part becomes almost equal to 1. Hence Relative time is equal to Proper time. Whereas for higher velocities, one needs to consider it for accurate calculations. One can actually experience Time dilation in real, but has to travel at a very high velocity to do so.

Now let us see, how it is correct technically.

clock placed on Earth(left), clock placed inside the Spacecraft(right)

Consider two clocks. Let one of them be placed on the Earth(right) and let another one be placed inside a moving spacecraft(left). Now, the clock mentioned here is a laser beam clock. It consists of two plane mirrors placed parallel and opposite. The light beam continuously moves to and fro and each time as it hits the mirror, it is considered as one tick. In the first case, the light beam has to travel a distance of 2L where as in the second case, light has to travel a distance of 2D which is greater. Thus 2D/c > 2L/c, therefore delta(t') > delta(t). It is quite natural to see that, the light beam on the spacecraft has travelled more distance with respect to the one on earth. Therefore the time interval between the two events is greater for delta(t'), thus we conclude that the moving clock ticks at a slower rate.

The blue clock is at rest and the red one is in motion.

Perception of Time dilation :

From the local frame of reference of the blue clock, the red clock, being in motion, is perceived as ticking slower. And it is also true for vice-versa.

Global Positioning System(GPS)

One of the real life application of Time dilation is working of GPS. Time dilation explains why two working clocks will report different times after different accelerations. For example, at the ISS time goes slower, lagging approximately 0.01 seconds behind for every 12 earth months passed. For GPS satellites to work, they must adjust for similar bending of spacetime to coordinate properly with systems on Earth.

We therefore observe that, Time dilation is experienced at each and every moment, but it is so negligibly small that, we cannot observe the difference. To experience it in large scale, one has to approach speed of light. Though Newton's laws of Motion is not 100% accurate, it is valid for small velocities, thus it is still excepted as a theory.

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" Time is a stubborn illusion, until you have your exams are near !! "

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#timedilation #relativity #einstein #newton #motion #rest

-ARJUN N K