### What is the Time?

Time is defined as an ordered arrangement of defined events, rather than a continuous flow of experience in an indivisible continuity.

It is something we all are familiar with, i.e., 60 seconds is one minute and 60 minutes is one hour, 24 hours in a day, and so on. This is called linear time, which is something we are familiar with and agree upon.

Now, if your friend comes to your home from a different city and asks you to draw time, so what would you draw?

You might draw a clock and point its hands to show him/her the time, or you may draw a calendar with cross marks over each day to represent the passing time.

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So, these all drawings would be the physical representations of the passing of the time.

This means time isn’t still just like a bottle kept on the table still for an infinite period.

These representations would just give the surface idea of time. However, to understand how it works we need to go beyond these daily lives representations of the time.

However, time is an arrow heading forward. Scientists called this arrow as the arrow of time.

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This arrow of time was originated at the Big Bang and has been moving ever since.

### Is Time an illusion?

In the classical theory of relativity, Einstein gave the following statements:

We describe motion as a function of time, like 10 meters per second, 20 miles per hour, or so.

The mathematical description of velocity is a topic of debate unless we define the time.

Nothing in the universe is in absolute motion or at absolute rest. All the bodies are in relative motion to each other.

Time is originated at the Big Bang and we are between the past and the unknown, turbulent future.

Hence, time is a stubborn illusion. For understanding the time, we need to understand relativity as a crucial subject.

So, what is time, and can we prove its existence?

### What is Time?

The time and its properties were known after studying the fastest thing in the universe, i.e., light; after researching the light particles and their speed, we needed to add up a new factor, i.e., time.

### How Time became So Important?

In the 19th century, Clerk Maxwell stated that light is an electromagnetic wave and travels in space with a constant speed, but relatively is it constant every time?

However, Einstein accepted the idea that the speed of light is constant for all the observers and he brought up the theory of relativity to make us understand this concept.

He stated that time is something that is the key to understanding relativity.

In 1905, he brought up a special theory of relativity, where he said that for the speed of light to be constant i.e., 186,000 mi/sec, one element must slow down and that element is time.

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Let’s consider an object in motion traveling with 90 % of the constant speed. To make it move comparatively at a constant speed (i.e., 186,000 mi/sec), it’s necessary to slow down its practically impossible time. however, many testings proved this phenomenon as true.

In time dilation, Einstein said time and space are the inseparable elements.

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According to this phenomenon, the speed at which you move forward in the space dimension, the slower the time dimension you will be in. As you reach the speed of the light, the time will stop, you cannot move further in the time dimension.

But the light travels in the form of photons which are massless packets, so it's impossible to reach its speed.

However, if we consider a situation, that a body moves with an acceleration ‘a’ and attracts the surrounding bodies, it gains mass and decelerates.

If theoretically, we exceed the speed of light, it would be possible to go in the past.

It may be possible if the time is created after the Big Bang.

However, time always goes forward, just like the entropy keeps on increasing.

It transforms from an ordered state to a disordered state after a certain time.

This means, before the Big Bang, the entropy of the universe was lesser. As time passes by, the entropy is also increasing.

So, the universe is reaching a disordered state with time.

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This is how the universe was created.

### The Standard Unit of Time

In International systems, the standard unit of time is seconds, denoted by ‘s’.

### Units of Time

The different units of time are:

Second

Minute

Hour

Day

Week

Month

Year

The SI unit of the time period is also second.

### The Largest Unit of Time

The largest unit is the supereon.

It is composed of eons where eons are divided into eras, which are, in turn, divided into periods, epochs, and ages.

## FAQs on The Idea of Time

Q1: Who Invented the Concept of Time?

Ans: In time close to 1500 B.C, the Egyptians introduced the measurement of time with the invention of sundials.

However, the time the Egyptians measured is not the same as the time today's clocks measure because this device is used to tell the time of day only when there is sunlight by the evident position of the Sun in the sky.

Q2: Does Time Exist?

Ans: Yes, it does exist.

We can estimate the time by using the concept of motion of one object relatively in motion with the other object passing by.

Like a complete revolution of the second’s hand of a clock make up the minutes, the complete revolution of the earth makes to a year.

So, time exists.

Q3: What are the different Units of a Second?

Ans: The unit of a second from the smallest to the largest values are:

Decisecond (1/10th of a second)

Centisecond (1/100th of a second)

Millisecond (1/1000th of a second)

Microsecond (One-millionth of a second)

Nanosecond (One-billionth of a second)

Picosecond (One-trillionth of a second)

Femtosecond (One-quadrillionth of a second)

Attosecond (One-quintillionth of a second)

Zeptosecond (One-sextillionth of a second)

Yoctosecond (One-septillionth of a second)

Planck time

Q4: What is the Unit of Frequency?

Ans: We know that unit of the period if second and frequency = 1/time period, i.e., its unit is per second.