The short answer
- The Big Bang was not an explosion in the familiar sense of the word.
- Scientists do not use the Big Bang to explain the origin of ordered structures in the later universe.
- The only order for which the Big Bang is thought to have been directly responsible is the uniformity of the early universe, which generally is thought to have been a consequence of an inflationary period.
The long answer
I am aware of three different ways in which creationists have argued against the Big Bang by appealing to the destructive power of explosions. The first way is to claim that an explosion could not have created the nearly uniform distribution of matter in the early universe. The second way is to claim that an explosion could not have created ordered cosmological structures like galaxies. The third way (seriously) is to claim that an explosion would have killed life instead of creating it.
I. Was the Big Bang an explosion?
One problem with all of these ways of arguing against the Big Bang is that the Big Bang was not really an explosion at all. When we use the word explosion we normally think of things like grenade blasts or supernovas, things which annihilate both the thing exploding and anything in the vicinity. However, these kinds of explosions are different from the Big Bang in a key way: they are material events that happen in space and time. The Big Bang, by contrast, involves the expansion of spacetime itself from a very tiny size to a very large size. There is no analogy at all between this kind of event and any kind of explosion we are familiar with; hence, there is no reason to think of the Big Bang as a destructive event or to believe that ordered structures could not have arisen in the universe as the expansion took place.
II. Why is the early universe so uniform?
Although the Big Bang was not an explosion, scientists nevertheless have wondered how the distribution of matter in the early universe came to be as uniform as it was. Although not without some controversy, the accepted explanation right now for this uniformity is that the matter was smoothed out during an inflationary period—a period very soon after Planck time when the universe underwent a period of exceptionally rapid expansion.
III. Could the Big Bang have created galaxies?
No one claims that the Big Bang directly produced things like galaxies: Big Bang theory simply describes the very early universe. The formation of structures like galaxies are a topic of cosmological investigation separate from Big Bang theory. It is typically thought that such structures developed through more mundane processes like gravitational accretion and shockwaves.
IV. Wouldn’t the Big Bang have destroyed life?
In a now defunct website that alleged to be an exposé of the “cult of evolution,” one creationist asked: “Do you really expect me to believe an explosion was the deciding factor in the creation of life? I thought explosions, of the magnitude that would send planets flying through the universe, would kill life, not create it!” (I have subsequently seen this question, along with a raft of others of similar quality, posted without attribution on several different message boards. For all I know, it was not even original to the first site.)
No one, of course, expects that creationist to believe any such thing; it is quite obvious to anyone who has read any mainstream account of the Big Bang that the Big Bang has nothing to do with the creation of life. According to the best current scientific estimate, the Big Bang took place 13.8 billion years ago. By contrast, life on Earth began no more than 4.5 billion years ago. Perhaps it is possible that life existed elsewhere in the universe at an earlier time, but I know of no scientist who claims that the Big Bang created life. Unfortunately, this creationist’s failure to do even the minimal research one could expect from a fifth-grader does not keep him from being extremely condescending towards the consensus of scholars who have devoted their entire lives to research in cosmology and astronomy.
If I may offer a personal anecdote, this last question brings to mind a discussion I once had with a creationist co-worker who asked me my thoughts about the history of the universe. At the time, she was a born-again Christian and I was an agnostic. When I mentioned the Big Bang, she rolled her eyes and said, dismissively, “Oh, isn’t that the theory that there was a huge bang, and all of the sudden there were dinosaurs?” I must have done a double-take, but I cared enough about her to try to sketch the actual theory for her, taking her through Planck time, the expansion of spacetime, and the stages of matter in the early universe. All the while, she just fixed me with a patronizing smile, a smile that said she thought it was so sad that I could actually believe there was a huge bang and then all of the sudden there were dinosaurs. I am sure she absorbed nothing of what I said, that her exposure to science continues to be mediated entirely by creationist literature, and that to this very day she continues to believe that the Big Bang was something like a nuclear blast in outer space that magically hurled out T-rexes and triceratopses. No doubt she also continues to congratulate herself on having more common sense than the entire scientific community. I feel genuinely sad for her: sad at the ignorance and unintended arrogance in which she likely will remain ensnared for the rest of her life, sad at the wonders of the natural world she will miss out on just because someone taught her to disdain science. She has been robbed. My memory of her and of so many creationists I have met who are like her is one of the main things that keeps me working on this guide.