The Big Bang: Let's Get Some Things Straight

In the wake of General Conference, I thought we might briefly review the science (which Elder Richard G. Scott has told us, is one of two ways to find truth) of the Big Bang.

What is the Big Bang?

In the mid-twentieth century, astronomers made some observations indicating that distant galaxies are moving away from each other, and that the universe is expanding. This implies that in the past they were much closer together. Astronomers reasoned that at some point in the past (~13.7 billion years ago) the universe was compressed into an extremely hot and dense state--so hot that atoms could not yet form because the high energies would rip them apart. The term Big Bang (initially coined as a term of mockery) refers to the rapid expansion of this compressed universe.

One prediction made based on the theory was that as the universe expanded and cooled, and atoms began to form, electromagnetic radiation should have begun escaping and might still be observable, but at much lower energy. The discovery of the cosmic microwave background in 1965 fulfilled this prediction and gave empirical support to the theory. Although the original Big Bang theory has been modified and added upon, these core features remain.

Was the Big Bang an explosion?

As mentioned above, the universe began in an extremely hot and dense state and rapidly expanded. In this sense, the Big Bang was like an explosion. However, the result of the Big Bang was not like that of explosions. One way of looking at entropy is as a measure of disorder in the universe. When we think of explosions, we think of ordered material being scattered into unordered pieces. From an energy perspective, concentrated energy in the fuel is released and converted into heat and kinetic energy. We end up with scattered pieces of matter, and energy converted into forms that aren't useful. In other words, explosions increase entropy. However, counter to intuition, the result of the Big Bang was a universe of low entropy. As the universe expanded and cooled, matter was able to condense into atoms--especially hydrogen. Hydrogen atoms were attracted to each other by gravity until they reached such density that they began to fuse together, forming stars. Stars have made the heavier elements of which we are composed.

The main point here is that the Big Bang did not use up fuel to scatter material throughout the universe. Rather, it created the raw fuel (hydrogen) from which all else would be made. In other words, the universe created by the Big Bang was one of low entropy and pregnant with potential.

Did the Big Bang create life?

Not directly, no. The Big Bang occurred about 13.7 billion years ago. Earth is only about 4.5 billion years old, so all life on Earth is obviously younger than that. All elements on Earth were created through the birth and death of stars.

Does order require intelligence?

There are many examples of order in the natural world that do not require intelligence. Many of the features of our universe (stars, galaxies, orbits, etc) are the result of simple laws like gravity. Intuition is not a good guide on these matters because nature is cleverer than we are. I covered this topic in a previous post, Order from Chaos. (It includes a couple of neat videos.) Similarly, there does not appear to be any natural law that would preclude the origin and evolution of life on Earth over billions of years by natural processes.

Whether divine intervention occurred in the formation of the universe or life on Earth is a historical question that cannot be ruled out by science, but neither does there seem to be any great need or evidence for it, scientifically speaking.


Further Reading:

Cosmology Primer

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