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Big Bang

The Story of the Universe

"How did we get here?" This is a question that has puzzled humans for thousands of years. From the earliest times in human history, people have been proposing answers to this eternal question. The same awe that drives us to question today has spurred countless theories from humans of all walks of life. Until recently, these theories have all been religious in nature, placing credit squarely on the good whims of a deity or deities. In the past century, though, scientists have been venturing their own ideas and making significant strides toward answering this age-old query.

The foremost of these explanations is the "Big Bang" theory. It states that our universe came from a tiny, extremely dense and hot state about 13.7 billion years ago. How this theory developed is important to understanding its validity.

Our ability as humans to observe the heavens has expanded exponentially since Galileo first peered through his then-revolutionary telescope. Since then our knowledge of what is beyond our Earth has grown and consequently changed dramatically. We realized that Earth is not the center of our solar system. We then found that our Sun is not the center of our galaxy. Eventually we even learned that our galaxy is nothing special, being only one of the more than one hundred billion galaxies like it in the observable universe. And we observed that most of those galaxies are actually moving away from us. Early on, the significance of this discovery was not realized. It was not until 1927, when a Roman Catholic priest named Georges Lemaitre derived the Friedmann-Lemaitre-Robertson-Walker equations from Albert Einstein's equations of general relativity, that the first glimmerings of a "big bang" theory arose.

The Friedmann equations relate various cosmological parameters within the context of general relativity, the breakthrough scientific discovery Albert Einstein made in the early twentieth century that changed forever our views of...