Was the singularity just a mini model of our current unvierse?

Question

Did the singularity just "containe" the matter, the energy and the space-time or it created them. If it just contianed them and then the expansion hppened, can we say it was just a mini model of our current universe And I can't imagine how it was. Can we say that the singularity was a ball that have a threre balls called "matter","energy" and "space-time" and they were beside each other?

Answer 1

Big Bang singularity cannot be treated as “point type explosion”. The problem arises when we think singularity as a “point in space-time”.

According to Einstein’s general theory of relativity, spacetime at every event has definite curvature. If that curvature is everywhere infinite, we define no spacetime at all. If we try to imagine the time of the big bang itself as being covered by of the cosmology, we are saying that there is a time at which spacetime is not properly defined. So, there can be no time in the cosmology corresponding to the big bang. We describe the big bang as a “singularity”, a breakdown in the laws that govern space and time. The term singularity, roughly speaking, designates a point in a mathematical structure where a quantity fails to be well defined, even though the quantity is well defined at all neighboring points. The simplest and best-known example arises with the inverse function, $1/x$. As long as $x$ is non-zero, $1/x$ is well defined.

For the $$\lim_{x \rightarrow 0^-} {\frac {1} {x}}=-\infty$$

And

$$\lim_{x \rightarrow 0^+} {\frac {1} {x}}=\infty$$

So in general we say $1/0$ goes to infinity but which infinity, what can be say about it ?

The safer course is just to say that we have a singularity at $x=0$ and not try to give it any value.

Answer 2

The singularity of the big bang is an artifact of extrapolating our understanding of physics beyond its breaking point. There is good evidence for what happened following the big bang, but as we approach it, the picture becomes vaguer and vaguer until we have no idea what was going on. The energy density present in the moments immediately following the big band were so high that are current physics is not able to accurately understand them. A simplistic way to understand why we say there was a big bang as the accepted cosmological model includes a term $a$ called the scale factor, which can be understood as determining how far apart things are in the universe. Through various astronomical observations, a graph of $a$ has been determined for (the majority of) the life of the universe. As we get close to what we call the big bang $a \to 0$, which is to say if we extrapolate our model we get that everything was on top of each other at the beginning of the universe. But we know the model breaks down before that point.