Formation of our Universe So I got this information from a magazine , Scientific American issue Physics at the Limits. The theory is that our Universe came about, when in the "Bulk Universe", which is four dimensional, a four dimensional Star collapsed and formed a black hole which became our 3 dimensional "Brane Universe", in which we live. My question is, how could this one Star have contained all the material that is in our Universe ?
I didn't read the SciAm article, but: Any cosmological theory compatible with "the" mainstream big bang theory doesn't assume material to have been contained in "Our Universe" (needs to be defined) from the very beginning.
Instead a very hot, unified state, is assumed, which then underwent several symmetry breakings (https://en.wikipedia.org/wiki/Symmetry_breaking, https://en.wikipedia.org/wiki/Higgs_mechanism), before "material" came into existence, as we observe it by now.

So, the very hypothetical, presumed four-dimensional star just needs to trigger an initial state causing the big bang. Whether "Our Universe" is a brane universe embedded in a higher-dimensional universe, is another mere hypothesis. Whatever "star" or "black hole" in a higher-dimensional universe would mean, the physics would be very different from the physics we can observe. For instance, inverse square laws wouldn't hold due to the additional dimension(s), hence orbital dynamics, electromagnetism needed for atoms, etc., all would either fail, or work rather different. Presuming the existence of stars in such a hypothetical universe is very daring, already.