The story Part 1

The universe originated in the Big Bang, a colossal event that, according to the inflationary theory, was accompanied by an unprecedented and extraordinarily rapid expansion over an infinitesimally brief period of time. Of the universe, the ordinary matter that we can directly perceive accounts for only about 5 percent. Approximately 27 percent consists of the mysterious dark matter, while the remaining 68 percent is made up of dark energy, whose nature remains largely unknown. It is this dark energy that is thought to be driving the expansion of the universe.