Quora answer: Did time come into existence after the Big Bang? If time didn’t exist then how was the Big Bang possible?
Objective spacetime definitely came into existence with the big bang as our universe appeared out of the multiverse (whatever that is) which is the meta-system or environment for all universes that is described by some string theory probably at the M-theory or F-theory level, i.e. at a level beyond what we can schematize. The pluriverse is the highest schema we have and that is 9 dimensional and string theory appears just beyond what we can schematize in the tenth dimension, then M theory unifies the various string theories that are possible in the eleventh dimension, and in the twelfth dimension there is F theory that is a further simplification, but also spawns two orthogonal time lines which we do not know what to do with. In the 14th dimension we get three orthogonal timelines. These extra orthogonal time lines is precisely what is needed to break down the fundamental assumptions of metaphysics which is that time is either linear or circular (eternal return, samsara). Primordial time must be something different from either circular or linear time. As Heidegger says in Primordial Time the various moments of time are equi-primordial, and the fact that there may be orthogonal time lines as Dunne thought back in the early twentieth century means that there must be other equi-primordial moments, so for instance the mythic time of the mythopoietic can be seen in these terms. We do not have to go very far to see how this other moment of four dimensional time worked, we merely have to go back before Thales in our own tradition and look at the Greek and other mythologies, which lost their force when the symmetry breaking of the metaphysical occurred producing the illusion of three dimensional time, plus lost time, just like Minkowski spacetime has nowhere beyond the light cones.
It turns out that orthogonal timelines is exactly what is needed to understand how there can be an operating system (pluriverse) for multiple universes of which our own is just one. The reason we have a schema for it is that we can experience the multiple timelines associated with each moment of time in our own lives, and did so enmass in the mythopoietic era prior to becoming free autonomous subjects as Descartes and Kant pictured us to be, and which we are trying to live out. However, if we go back to Homer as Kelly and Deryfus do we can see that the early Greeks had a completely different orientation to the world, which they see as arising again in Melville that we associate with polytheism which they think exists before and after the monotheistic imperative we have been living out in the metaphysical era. However, since spacetime itself is projected according to Kant and not objective from our vantage point, and since objective spacetime is a noumena, then even saying that there is multidimensional space and multidimensional time is our own projection, and what existed in the multiverse is an unknown unknown which we can speculate about, unless we find some signature of it on our universe we will never know anything about it. Since there was a signature of the Big Bang (cosmic background radiation) and we can even figure out that the universe is till accelerating in its expansion, so we know that dark energy is streaming into our universe from somewhere. Since we have been able to figure out these things then we might find a meta-cosmic signature of the pluriverse somehow inscribed into our universe. But until then even the projection of multiple orthogonal timelines in the Matrix of multi-dimensional spacetime/timespace is merely our own projection from what we know about time and space in our own universe that makes our life possible on this small planet in the midst of an immense void.