The Big Bang refers to the currently held and most popular theory of creation in science. Everything that exists; all the stuff that ever is or was, has always existed but was at one time all in one small spot. That spot was really hot and really dense. Likely as a result of random quantum fluctuation, the universe expanded very quickly. That expansion continues today and is even currently accelerating. As it flew apart and cooled, the universe became transparent and energy became matter.

Early matter in the universe was cheap. Pretty much just hydrogen and helium. These are very simple elements, but when you get a whole lot of them together via gravity in one place, star formation is the result. Stars not only produce all kinds of radiation, they also manufacture the heavier elements up to iron. If a star explodes as a Supernova, that explosion creates and scatters heavier elements such as gold and uranium. Our solar system was formed from the debris of many old stars. The iron in your blood was made from a star, the carbon in your skin and hair came from a star. We are all composed of starstuff!

The Big Bang theory is holding strong because the expansion of the Universe can be easily observed and because there is an even amount of background radiation across the universe - a kind of smoking gun. That the universe (specifically the space between the stuff) is growing and was the result of a tremendous accelerated expansion is a given. How that expansion came about is a subject still being tackled. What has recently been determined is that the Universe will very likely go on expanding forever - until all the stars burn out and all energy is lost. Kinda depressing in a way, but the prospect of "alternate universes" is currently under debate.

5 Billion years ago: The Formation of the Earth.

The early formation years of the Earth is known as the Precambrian Eon.

How the solar system formed is currently being hotly debated. Very recent observations of other solar systems and star birthing areas have tossed out a lot of previously held assumptions. At any rate, we are very lucky that the Earth is exactly positioned where it is and that it was able to form the way it did. Any slight variations in its size, position, and composition may have made life impossible. So the Earth cools, but maintains a molten core to this day - very important for things like plate tectonics, which many scientists feel is essential for bio-diversity. Life probably started almost as soon as it could. It turns out that basic life is not too tricky a thing to create, providing the right conditions exist. The early earth had the right stuff. In fact, if you toss together methane, hydrogen, ammonia and carbon dioxide (all components of Earth's early atmosphere,) - and then zap it with some electricity (lightning - also likely to be in abundance back then,) you will form amino acids in just a couple of hours. Amino acids are the basic building blocks of proteins, which are molecules that do the work in living systems. So you're not making life, but you are starting with non-living material and ending up with the simplest material that make up a living cell. This is called the Miller/Urey experiment.

So all these amino acids rain down into the oceans for a few hundred thousand years making the early earth a smelly but nutient-rich place. This is what they call the "primordial soup." How the first cells and single cell animals formed nobody knows, but its most likely to do with naturally occuring bubbles inside clay (that prevented the proteins from being zapped by ultra-violet radiation from the sun, and by chemicals in the oceans.

9 Billion to 150 Billion Years Ago:

To get from early cell development to the era of primates takes a long time. Rocks from space bash into the Earth at regular intervals killing everything off, but life persists.

Human beings evolve during the Pleistocene era, and almost immediately express themselves in creative ways. Art exists as soon as humans become self-aware and expressive. Humans have evolved sufficiently to be able to think and not just react. Evolution is still a sticky business, but other "creation" views persist. An excellent place to start investigating this is HERE. For a non-science view of creation, click here.