What is one of the primary unanswered questions about the origin of the universe? What type of elements formed first? Approximately how long ago did the big bang occur? How long did it take the earth to form? What came before the big bang?

Primary unanswered questions about the origin of the universe: How is the universe form? and What would happen to the universe if the values of these physical constant were changed?

Type of elements formed first: Hydrogen and Helium

Big Bang occur in one second.

The Earth formed 15 billion years ago. (As galaxies cluster together under gravity, the first stars die and spew heavy elements into space; these will eventually form into new stars and planets.)

Possible evidences came before Big Bang:

a. The cosmos goes through a super-fast "inflation", expanding from the size of an atom to that of a grapefruit in a tiny fraction of a second.

b. Post-inflation, the universe is a seething, hot soup of electrons, quarks and other particles.

c. A rapidly cooling cosmos permits quarks to clump into protons and neutrons.