Arrange the following statements about the Big Bang Theory in chronological order. Hydrogen atoms were forced together under the force of gravity, forming stars and galaxies through nuclear
fusion.
= After one second, the new universe expanded and cooled, forming protons and neutrons.
After several thousand years, cosmic microwave background formed the first light that began to shine in the
universe.
Under extremely hot and dense conditions, a single point called a singularity began to expand, causing a
sudden, massive explosion.
= Electrons became attracted to protons and neutrons, forming hydrogen and helium atoms.