Since the dawn of civilization man has gazed in awe at the stars, wondering what they are and how they got there. Although on a clear night the unaided human eye can see about 6,000 stars. Hubble and other powerful telescopes indicate there are trillions of them clustered in over 100 billion galaxies. Our sun is like one grain of sand amidst the world’s beaches.
However, prior to the 20th century, the majority of scientists believed our own Milky Way galaxy was the entire universe, and that only about 100 million stars existed.
Most scientists believed that our universe never had a beginning. They believed mass, space, and energy had always existed.
But in the early 20th century, astronomer Edwin Hubble discovered the universe is expanding. Rewinding the process mathematically, he calculated that everything in the universe, including matter, energy, space, and even time itself, actually had a beginning.
Shockwaves rang loudly throughout the scientific community. Many scientists, including Einstein, reacted negatively. In what Einstein later called “the biggest blunder of my life,” he fudged the equations to avoid the implication of a beginning. 
Perhaps the most vocal adversary of the idea that the universe had a beginning was British astronomer Sir Fred Hoyle, who sarcastically nicknamed the creation event a “big bang.” He stubbornly held to his steady-state theory that the universe has always existed. So did Einstein and other scientists until the evidence for a beginning became overwhelming. The “elephant in the room” implication of a beginning is that something or Someone beyond scientific investigation must have started it all.
Finally, in 1992, COBE satellite experiments proved that the universe really did have a one-time beginning in an incredible flash of light and energy. Although some scientists called it the moment of creation, most preferred referring to it as the “big bang.”
Astronomer Robert Jastrow tries to help us imagine how it all began. “The picture suggests the explosion of a cosmic hydrogen bomb. The instant in which the cosmic bomb exploded marked the birth of the Universe.”