To start with:
We need to understand the Dimension first and then Physical entity (Existence/Creation):
Dimension: It can be defined as the measure of a particular property of an entity.
Basic dimensions: Mass, Length, Time, Temperature etc.
We can clearly make a distinction for spatial dimension; Length is just a mathematical dimension but certainly not a physical entity. Basic dimension and mathematical entities cannot be regarded as not physical entities, for example, length of a line is not a physical entity itself and length of a box where box (part of existence) is a physical entity.
Existence: It includes universe/multiverse, it can be defined as a self-existing multi-dimensional entity, infinite in nature, it consists of all other entities that ever existed or existing now or will exist; such as matter, antimatter, waves, energy, force fields, spatial expanse (includes emptiness and non-emptiness) etc.
Non-Existence: It can be defined as an entity that never existed, nor existing now and will never exist.
It can be a little confusing that “Non-Existence” word exists. As mentioned earlier these words are just a symbol to represent non-existing but not the actual entity.
Time: It is a mathematical dimension to measure the change of state (any motion) of Existence (includes universe/multiverse).
Space: It is a mathematical dimension to measure the spatial expanse of Existence (includes emptiness and non-emptiness).
In this case, Existence and part of the existence is the only physical entity where Time and Space are just dimensions like others i.e. Mass, temperature etc.
Spatial expanse of Existence: It can be defined as a physical entity (part of Existence) which can contain nothing inside it (emptiness) or some physical entity filling it (non-emptiness).
Note: Vacuum does not mean spatial expanse, it just represents emptiness, while spatial expanse includes vacuum and non-vacuum both.
The density outside the earth’s atmosphere is less than 1 hydrogen atom per cubic centimetre. So we can consider the distance between the 2 hydrogen atoms is minimum 1 centimetre. Only if we consider spatial expanse as a physical entity of Existence between them, then only we will be able to observe the distance between 2 hydrogen atoms. Else we would not be able to observe the distance between them, because there is empty vacuum only and nothing else exists between them. And if we consider this empty spatial expanse as Non-Existence then there should not be any distance between them.
All physical entities are present in the infinite spatial expanse of Existence, it could be so vast that if we consider our universe as a small particle of light then the spatial expanse might be equal to the Pacific Ocean or more. This example is just for an illustration purpose as spatial expanse could be infinite in nature.
There is a theory of the presence of dark matter (never been detected directly) in the emptiness of our universe due to which our universe is expanding exponentially. It might be possible that our universe is just getting absorbed into the vast infinite spatial expanse of Existence. (The detailed discussion of this topic has not been included in this research as it is a full research topic to cover).
RESEARCH and DISCUSSION
Now there is a term physical Spacetime based on Einstein's theory of relativity
Accordingly, Spacetime can be explained as four dimensions in Euclidean geometry. Time can be referred as fourth dimension in which the universe is existing in past but we have already passed through that time and universe is existing in future but we have not encountered it yet.
The Spacetime is one physical entity woven together and is considered as basic fabric of universe dynamically curved due to the presence of matter. It also states that the initial singularity was infinitely dense and so was the infinite curvature of Spacetime and nothing existed beyond (before and outside) it. At the time of Big Bang explosion, all the dimensions got unwarped including Spacetime and we see the universe as it is now.
This theory puts a fullstop to measure any possiblity beyond Bigbang as there is no dimension to measure any type of existence.
In mathematical physics, Minkowski spacetime is a combination of three-dimensional Euclidean space and time into a four-dimensional manifold where the spacetime interval between any two events is independent of the inertial frame of reference in which they are recorded. Although initially developed by mathematician Hermann Minkowski for Maxwell's equations of electromagnetism, the mathematical structure of Minkowski spacetime was shown to be an immediate consequence of the postulates of special relativity. Source: https://en.wikipedia.org/wiki/Minkowski_space
There are many practical significance of this theory; one of them is time dilation effect on the clocks of International space station and GPS satellites compared to the clocks on earth.
Now, I will highlight our time measurement techniques once. We measure time through different types of clocks, and clocks are the devices to measure unit of time defined by us (S.I units). These clocks cannot measure the unit of time independently without being affected by the physical laws of existence and have to abide by these laws such as gravity and velocity.
Should we consider time dilation shown on our clocks as actual time dilation?
The laws of existence affect all the physical entities in a different way. All the physical entities have a different effect of gravity on them depending on their nature. It is not necessary that the biological clock of living beings would be affected in same measurement scale as it affects the normal clocks.
Note: No such empirical research has been done so far to check time dilation in all variety of clock (based on different technology) is the same or different.
Also, there are many paradoxes related to time travel and relative time. If Time is just the measure of a physical entity called existence/creation then there would be no room for such paradoxes.
This theory puts forward the concept that Existence/Creation is the only physical entity where we exist and all the dimensions are a form of knowledge to measure/describe it. It will change the whole concept of Time and Space from being a physical entity to a pure Mathematical dimension like other dimensions such as Mass, length, temperature etc. Eventually, it will end all the possibilities of time travel and related paradoxes because one has to change the state of entire existence into past/future state in order to travel in time which is not possible. However, it will open the possibilities to measure beyond Bigbang and expand the horizons of our present knowledge.
Let me know your valuable thoughts and reviews on this theory.
(References available upon request as there is limited space here so I tried to summarize the whole concept)