Hopefully somebody knowledgeable in these questions will speak up.

I am not knowledgeable. Here is where I might start if I had your questions:

https://en.wikipedia.org/wiki/Cosmology Read the page and follow the links outward, according to your questions and interests.

https://en.wikipedia.org/wiki/Portal:Contents/Portals#Natura...

Good luck. Report back when you have an answer. :)