Einsteinian concept of space time

1.0. Introduction
Meditations on the nature of time began with the questions about its nature of existence.   Though many problems are related to the concept of time, these problems will be more in the epistemological realm and less in the ontological level.   ‘Time is the basic category of existence,’ wrote Heidegger, referring very definitely to time. Time is ‘the immediate datum of consciousness,’ said Bergson.   Time, for Kant, is ‘the formal a priori condition of all appearance whatsoever.’   Aristotle defined time as ‘the number of motion in respect of before and after.’   St. Augustine, when asked about time, conferred: ‘What, then, is time? If no one asks me, I know; if I wish to explain to him who asks, I know not.’

In his book A Sense of Time Vatsyayan explains beautifully, the different thoughts about time.   Usually when somebody says to us “you missed meeting him; he was waiting for you long time.”   Then I may ask, ‘when did he go?’   The answer can be: “he came at 12 o’ clock and went just now; he must have reached the road junction.”   Here my question was about time, but the answer was related to space and distance i.e. 12 o’ clock is when the small and big metallic pointers in the clock meets at 12, which is a spatial representation and ‘road junction (from the house)’ is distance.   Ordinary use of time is without much problem provided we have a watch or clock and we know how to say it.   This experiential aspect gives rise to the philosophical aspects when we dive deep into the river of time.   It is interesting to quote Kant here ‘Time is ideal, but the concept of time is not derived from sense experience alone...[further] Kant insists that all possible knowledge of objects must be tied to and constrained by sense experience.’

2.0. What is Time?
A question we generally ask and easily get the answer immediately is ‘what’s time?’   But if somebody stares at us when the question is asked he must be a philosopher....