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How to Understand the Big Bang

An unimaginably long time ago-perhaps as few as 13 billion years, perhaps as many as 20-our universe sprang into existence in an incredibly hot and dense fireball. This "Big Bang," as physicists call it, is an easy concept to intuitively grasp, but a difficult one to really understand. The following points will give you a firmer grounding in this cosmological theory.

Instructions

- 1
  Abandon your preconceived notions of time and space. It's a common error to picture the Big Bang happening in a preexisting space, like a bomb going off in a big room. But the Big Bang actually created space, as well as all the matter and energy in the universe. This makes the Big Bang (technically) impossible to picture, though it can't hurt to try.
- 2
  Picture space expanding in all directions. Another naïve belief about the Big Bang is that it implies that the universe has a "center" from which everything expands, as in an ordinary explosion. However, because the Big Bang created space as well as matter, every galaxy in the universe today is speeding away from most every other galaxy, so the universe has no geographic center (except in a hard-to-visualize fourth-dimensional sense).
- 3
  The Big Bang didn't originate from nothing. Even though matter and energy didn't exist before the Big Bang (whatever "before" means in this context), the rules of quantum physics and general relativity presumably did exist, thus allowing the universe to spring into being. In short, if there were no preexisting laws of physics, none of us would be here!
- 4
  Don't be too concerned about the timing. Measuring the light of distant galaxies (and thus calculating how fast they're rushing away from our own galaxy) is a delicate task. For this reason, the precise timing of the Big Bang (within a half-billion years or so) tends to fluctuate by a few billion years at any given time. This doesn't mean there's something intrinsically wrong with the theory; it just means that the measurements haven't quite caught up to the mathematics.
- 5
  Understand that the Big Bang isn't the end of the story. Today, very few physicists believe in an unadorned Big Bang. A period of "inflation" is usually thrown in (a split-second after the initial explosion) that multiplies the volume of space by an exponential amount. Despite these corrections to the original theory, though, all the evidence still points to the singular origin of our universe in a Big Bang-like event.

Astronomy