It is my understanding that the density of the universe billions of years ago was radically different from the one we now observe
It’s even more puzzling than that. Our current model features a period of time called the inflationary epoch which lasted between 10^-36 and 10^-33 or so seconds after the Big Bang, in which the universe expanded by a factor of at least 10^26 along each linear direction [1].
This is unfathomably rapid expansion. It makes sense mathematically but not at all intuitively. It’s totally bizarre and weird and I don’t have even close to the level of background needed to challenge it!
It’s even more puzzling than that. Our current model features a period of time called the inflationary epoch which lasted between 10^-36 and 10^-33 or so seconds after the Big Bang, in which the universe expanded by a factor of at least 10^26 along each linear direction [1].
This is unfathomably rapid expansion. It makes sense mathematically but not at all intuitively. It’s totally bizarre and weird and I don’t have even close to the level of background needed to challenge it!
[1] https://en.wikipedia.org/wiki/Inflation_(cosmology)