Question

What is meant by the term "the era of nucleosynthesis?" Why is this important in our study of astronomy?

Answer 1

The eras of bigbang describes the creation of universe from the beginning of universe in which very first era is planck era in which all four forces of nature were unified and there after GUT era in gravitational force separates from other three forces and after that electroweak era in which nuclear strong force "freezes out" and becomes distinct from other two forces there after particle era leads to the the formation of particles in universe and after that comes the era of nucleosythesis which nuclear fusion reaction between particles takes place and leads to the formation of helium and some heavy atoms in universe.

Now this era is of great interest because we know that first generation stars are made of helium and hydrogen and source of there energy is nuclear fusion reaction in the core of stars. This era was started just after one millisecond after bigbang and created helium and heavy elements in universe. So in this time universe was so dense that formed nuclei again broke apart as soon as they formed. This formation and broke up lasted 3 minutes and after that as universe cooled down, stable helium and other particles were created .

So this how at the end of this era universe had enough amount of helium to form stars, so that's why this era is important in study of astronomy.