The Beginning of Time

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[edit] Discussion

A common conceptual problem when discussing the Big Bang Theory usually comes in the form of the question, "but what came before the Big Bang?" On the surface, this appears to be a natural line of reasoning given our everyday experience of how time works. Given our post-Relativity understanding, however, the concept of "before" the Big Bang quickly becomes nonsensical.

There are some key facts that must be understood before we may continue.

The first is spacetime. One of the major consequences of Einstein's General Theory of Relativity is that our everyday idea of space and time as two distinctly different kinds of things is incorrect. Space and time are two different perceptions we have of a common thing, which Einstein creatively dubbed "spacetime". The simplest way to conceptualize spacetime is to start with 3-dimensional spacetime. It is 3-dimensional in that any object in it has a length, width, and height. It can be measured by three measurements. Now, understanding that time is same thing as space, we can add a fourth dimension to our 3-dimensional space model to arrive at 4-dimensional spacetime (length, width, height, and duration).

A much more difficult property to understand of spacetime is that there is nothing special or unique about the "time" dimension of spacetime. It is no different than the three "space" dimensions. In other words, what may be "left" here in our portion of spacetime could be "future" in another part of spacetime.

"Before" is a concept inherently linked to our concept of linear time. That is, we think of ourselves moving on a line from the past to the future and "before" refers to a past-ward direction from a specific point on that line. Given, however, that the direction we label "past" is not necessarily the same direction labeled as "past" in some other part of the universe, The universe does not have an absolute time line, only a local one.

The second key fact that must be understood is that matter and energy are interdependent with spacetime. Without matter and energy, there can be no spacetime. Without spacetime, there is nowhere for matter to be. The reason for this is beyond the scope of this article.

The third key fact is that the current best theory is that the Big Bang was triggered by quantum fluctuations, which are the spontaneous creation and subsequent destruction of quantum level pieces of matter. Again, the reason why this happens is beyond the scope of this article.

Now, given that spacetime is dependent upon the existence of matter and energy, the quantum fluctuation that was responsible for triggering the Big Bang is also responsible for bringing spacetime into existence. More to the point of this discussion and in everyday terms, it brought time into existence. Thus, it is nonsensical to talk of a time "before the Big Bang" because it is equivalent to talking of a time "before time" or asking "What is North of the North Pole ?"