It is my understanding that 13.7b years ago is simpy when time started in our universe. Space still existed in the singularity state, no? Whether or not there is a multiverse is still hypothetical, no? |
The singularity is not an object. It's a mathematical conundrum, a place where our current understanding of physics is incapable of making accurate predictions.
At T=0, roughly 13.7 billion years ago, reversing the observed expansion of the Universe leads us to a point where the spacial dimensions consist of a single, dimensionless point, in which all of the mass/energy of the Universe was compressed. This point is the Universe. It does not exist in space, it is space, as well as time (time is just another dimension, like length or width or height). Basically, the incredible density of the Universe at this location in time means that spacetime would have been warped to an infinite degree.
The Universe is not expanding into space - space itself is expanding. Length, width, and height are getting larger. Matter is not flying apart from a central explosion; literally the space in between any two objects is increasing without movement, something like stationary ants on an inflating balloon.
It's not "when time started." T=0 is simply the minimum value of the time dimension. Saying that "time started" is no more accurate than saying that the North Pole is where the surface of the Earth started.
The problem when discussing this topic is that the closer we approach to T=0, the less human beings are able to intuitively grasp and understand what's being talked about. We need incredibly complex math to model these concepts, and when physicists "dumb it down" to the level of the layperson, we wind up with the sorts of misconceptions that ICANT commonly clings to.
The words "beginning" and "started" stop being useful when we discuss an absolute minimum value for the time dimension. Saying time "started" requires a previous moment in time where time was "stopped," which is self-contradictory because it requires a coordinate outside of the scope of the coordinate set. What coordinate is farther North than the North Pole? The question has no meaning.