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This is the second part of our series The Mystery of Space-Time Relativy.
If u missed our first part then watch our first part which is All About Gravity, links here:
https://youtu.be/7CeNjYzpmgM

Today we are going to talk about Space-Time whether its real or an illusion. So let’s get started.
So the question arises while understanding SpaceTime is that what is time? Is it related with space?
Before Einstein’s era, scientists believed that space and time are independent of each other. Neither of them is related in any manner. So any change in time doesnot affect space and also any change in space doesnot change time.
According to Newton, Time is absolute irrespective of any point in space. Which means if i spend 1hour on earth that means everywhere in the universe 1hour has passed whether anyone is on Mars, Jupiter or travelling with the speed of light or may be near a black hole.
Now lets understand Space and time separately, Space is everything we see around us. Each and every object is a part of space. To denote the position of an object in space, we use the 3-dimentional co-ordinate system.
Now time is something every one knows that it keeps moving forward. It is also called time dimension or the fourth dimension. And mixing it with 3-dimentional space, it creates a 4-dimentional space-time.
But despite of different characteristics, Einstein believed that Space and time are relative i.e they are related to each other. He said that time is relative and not absolute, which means that time passes with different speed depending on the situation and condition. The speed of time for an object depends on the velocity of the object and also on the gravitational field of the object. The speed of time slows down with the increase of the velocity and gravity for the object.
Lets understand this with two examples.
Let us take two planets our earth and Jupiter. As Jupiter is much larger than The Earth and also have a larger mass than earth, so the gravity on Jupiter will be more than that of our earth. So the speed of time on Jupiter will be slower than on earth. Hence, if a person travels to Jupiter and lives there then he will live longer than those people on earth as time will slow down for him.
Again time also depends on speed of the object, so let’s take two twin brothers. Now if one brother stays on earth and the other goes in a space mission travelling with high speed with almost the speed of light. Then what happens, the time for the brother travelling with the speed of light gets slower. Now when the brother returns back to earth after a couple of years, he will see that his brother has grown old while his age has just been increased by 2 years.
This phenomenon states that time and space are related with each other. And here the concept of Time dilation and length contraction comes into play. We will understand this topic in other videos.
Now acc