By Ron Cowen
The Big Bang wasn’t all it has been cracked up to be. Sure, it created the universe. But after the heat of the primordial fireball faded, the cosmos plunged into darkness. The universe was cold and black — a sea of hydrogen and helium atoms mixed with a mysterious dark form of matter making its presence known only by its gravity. No stars.
It took a series of violent events — starting about 100 million years after the Big Bang—to end the cosmic Dark Ages. First, the evenly spread dark matter gathered into clumps, pulling in hydrogen gas that coalesced into clouds. Then pressure inside the clouds grew strong enough to fuse atoms, triggering nuclear reactions. The first stars created this way looked like roses with diaphanous petals, unfolding against a sea of darkness. The universe was finally in bloom.
The first stars marked a milestone in the history of the universe, bringing light and warmth back to the cosmos. Later, those primeval stars met their end in spectacular explosions known as supernovas, which seeded the universe with its first dollops of oxygen, carbon and silicon. Those elements made it possible for a second generation of stars to form.