Hello everyone! I am Rahul here and I am back again with another article related to science. Today I will be explaining what is space-time? I will try to keep it as simple as possible without diluting the real facts. So let's start.
ORIGIN OF SPACE-TIME CONCEPT
Before 1908 scientists used to think that space and time are independent and in now they depend on each other. Newton said that if here on earth for someone two hours has been passed then for someone else at any place in this universe no matter what also experiences two hours. But in 1908, Hermann Minkowski in one of his essay suggested space-time. He on the basis of Einstein's theory of Special Relativity said that both and space and time are dependant on each other and no one can exist without another in his concept of Minkowski space. It was actually Hermann Minkowski who first proposed the idea of the space-time continuum and not Einstein. Minkowski space concept was just only accurate in explaining why speed of light is constant but in 1915 it was Einstein who on the basis of his General Theory of Relativity considered the effects of acceleration and generalized Minkowski space-time. Einstein discovered that the curvature in his 4-dimensional space-time representation was actually the cause of gravity.
Now let's understand what is space-time continuum.
WHAT IS SPACE-TIME?
To understand this concept better we will first have to understand what is space and time individually.
SPACE
We know that everything around us occupies some space. But what do we mean when we say space? When we mean that something occupies some space we mean that object has some length, breadth and height. To understand it better see this image:
In this image, we can represent length, breadth and height on x,y, z-axis respectively. That's how we represent 3D objects around us on a piece of paper. To represent an object moving in space we can use this 3D representation. For the sake of simplicity let's consider an example by using only 2D coordinates, i.e. x and y-axis only.
You would have already learned about this in your maths class so I won't go any deeper than this.
Now let's understand what do we mean by time.
TIME
Understanding time is a little bit difficult. Physicists define time as the progression of events from the past to the present into the future. It never goes backward and always continues to go in the forward direction. The question of why time is irreversible is one of the biggest unresolved questions in science. You won't be reading this article if you won't have time. Everything will seem to be still if time was not running. I hope you got my point.
By coalescing them together now we can understand the concept of space-time.
SPACE-TIME
Space-time is basically a blend of time and 3D coordinate. Time is considered as the 4th dimension. Let's take an example to understand it better. For the sake of simplicity, I will be using 2D representation. Let's take x-axis as SPACE and y-axis as TIME as shown in the image.
As you can see in the graph when an object moves in space it also moves in time. This implies that no object can move without experiencing time. But an object can move forward in time without moving in space. Space-Time is like a 4D fabric spread through our universe on which different objects(stars, planets, humans, etc.) are lying which makes it warped and dynamically curved like this:
With this warps in space-time fabric Einstein explained time dilation. I will tell about time dilation in detail in another article later. For now, we will just go through its definition. The definition is according to Wikipedia.
TIME DILATION: is a physics concept about changes in the passage of time, as related to relativity. It is a difference of elapsed time between two events as measured by observers. In Albert Einstein's theories of relativity, there are two types of time dilation:
Case #1: In special relativity, clocks that are moving run slower according to a stationary observer's clock. This effect does not come from workings of the clocks, but from the nature of spacetime.
Case #2: the observers may be in positions with different gravitational masses. In general relativity, clocks that are near a strong gravitational field run slower than clocks in a weaker gravitational field.
The concept of time dilation has also been verified by physicists. You can learn more about it from here.
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That's all for today, hope you enjoyed it. If you have any doubt, ask in the comment section.
In the next article, I will explain Time Dilation in detail. Till then goodbye and take care and be ready to get your mind blown.
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References:
- Space-Time: Simple English Wikipedia
- Space-Time explained in Hindi - What is SpaceTime
- Einstein's Time Dilation prediction verified