At the moment of the "big bang", science tells us nothing at all.
I was assuming that people reading the post would understand Planck Time. Yes I shouldn't assume. In Big Bang cosmology, the Planck epoch or Planck era refers to the earliest stage of the Big Bang, before the time passed was equal to the Planck time, tP, or approximately 10−43 seconds. So what I was saying was that at 10-43 seconds after the Big Bang, all matter we see in the Universe today was condensed into a space smaller than an atom, ergo, denser than a Black Hole or Neutron Star. There is also a theory for what was around before the Big Bang and that is String Theory.
https://phys.org/news/2006-03-string-theory-notion-redefines-big.html