Our current understanding of Universe
In this chapter we will explore the theories that describes how our universe got started and what are our limitations upto now and what are the new possible theories explaining before everything got started.
In previous topic of 'an interesting history of Time and Space', Isaac Newton gave the theory of absolute Time (ab. Time) and absolute Space (ab. Space). (from here onwards it is also represented as ab. Time & Space on many occasions). According to this theory ab. Time and Space are not affected by any entity of universe and they are infinite in nature.
However there was another theory given by Einstein (theory of relativity) which says that Time and Space are one single physical entity called Spacetime, which bends and deform according to the presence of matter in universe. It has a definite start point called Bigbang explosion.
According to the theory of relativity, the initial singularity was infinitely dense due to which there was infinite spacetime curvature. It means no space and time beyond it. With the bigbang explosion from that singularity, all the dimensions unwarped and we are able to see the spatial expanse of the universe as it is now. Theory of relativity completely changed the notion of ab. time & space (not a physical entity) to relative Spacetime (physical entity) opening the possibility of going backward/forward in time.
There are some other theories describing the state and source of initial singularity which we will discuss in next chapter Existence and Universe. We will also see if there was any “Time & Space” existed beyond that bigbang or not. In order to check this, first, we need to discuss whether universe should be called Existence or Universe itself.
According to our current definition of universe, both seems to be same because nothing exists outside the universe and universe itself is whole existence. Now we need to explore them further to understand the difference between the definitions of these words.
Let’s move further with some questions arisen due to the above discussion, also we are going to address few supplementary questions inside these upcoming chapters.
1. What is the difference between existence and universe?
2. What is ab. Time and ab. Space?
3. What is Absolute Time and time travel?
4. What is Spacetime and time travel?