Been a while since chem & physics class for me as well.
How are these estimations calculated, and to what certainty? Surely, these are calculations only from the observable universe?
How are these estimations calculated, and to what certainty? Surely, these are calculations only from the observable universe?
I suspect there is mathematical modeling.
Interstellar dust might provide the spectrum instead of stars, although that really only tells us the composition of the milky way.