Physics

As part of its life cycle, a star changes from being a protostar to a main sequence star. Explain the difference between a protostar and a main sequence star.

A protostar is at a lower temperature as nuclear fusion reactions have not started.

The early Universe contained only atoms of hydrogen. The Universe now contains atoms of over one hundred different elements. Explain how the different elements now contained in the Universe were formed. 

Elements as heavy as…