1.2 NOTES The history of Universe 09/12/2013
1. BY ORDER:
A. BIG BANG : (hot/dense explosion) The expansion of the universe begins.
B. The force of gravity draws matter together to form galaxies and galaxy clusters. ▯ only 2 elements ,
Hydrogen and Helium.
C. Gravity drives the collapse of clouds of gas and dust to form stars and planets.
D. STAR CYCLE:
I) The star is born when gravity compresses the material in a could to the point at which the center
becomes dense + hot enough to generate energy by “nuclear fusion”: lightweight atomic nuclei smash
together and fuse to make heavier nuclei.
II) Star shines with energy that is released by nuclear fusion and creates all the other elements (heavier
than hydrogen and helium)
III) Stars explode when they die, scattering the elements they’ve produced into space. bac