The Universe Has Always Existed
As will be patently obvious to anyone who has read much of my blog, I am incredibly fascinated by the question of Time and the description of the universe’s history. The topic is incredibly complex and wonderfully intricate. Unfortunately, these peculiarities can very often lead to very common misconceptions. One of the misconceptions which I encounter most often is the idea that there was once a state in which the universe did not exist.
This misconception has arisen because, over the past century, it has become increasingly plausible that the universe may not extend infinitely into the past. Thanks to Big Bang Cosmology, the previously prevailing view of Aristotle that the universe is static and eternal has been almost entirely abandoned. It is entirely possible– and perhaps even likely, given certain assumptions– that the universe has a finite history. That is to say, there was a first Moment of Time. Given this, people naturally wonder, “Well, what happened before that?” Unfortunately, these people don’t realize that the question which they are asking is entirely nonsensical.
Whether the universe is past-finite or past-infinite, it has always existed.
If the universe extends infinitely into the past, it is trivial to see that it has always existed. However, what if it does not? How can I justify my claim if the universe has a finite past? Consider the following argument.
- The universe is the set of all physical things which really exist.
- Time is a physical thing which really exists.
- If Time exists, then the universe exists. (1,2)
- Time is the set of all moments which exist.
- There exists some moment, t.
- If t exists, then Time exists. (4,5)
- Therefore, if t exists, then the universe exists. (6,3)
- The phrase “always” is defined as meaning “for all moments of time.”
- There are no moments of time in which the universe does not exist. (7)
- Therefore, the universe has always existed. (8,9)
The logic is fairly simple to follow, but it grinds against people’s intuition to think that there may have been a hard boundary to Time. They simply have this intuitive sense that, for any moment of time, there must have been some moment which preceded it. However, this may not necessarily be the case. If Time is past-finite, then there are no moments of time which precede the first moment.
Asking “What happened before the first moment of Time?” is precisely akin to “What place lies north of the North Pole?” There are no places to the north of the North Pole. The North Pole is the northernmost point on the globe. If you were to be standing on the North Pole, and you took one big step in any direction, that step would take you directly south. In exactly the same way, it does not make sense to ask, “What happened before the first moment of Time?” There is no way for a thing to happen before the first moment of Time, because things only happen within Time, and there is no Time which exists before the first moment.
The universe has always existed. Now, the question of whether its history is past-infinite or past-finite is certainly intriguing, and well worth study, but it is ultimately irrelevant to the question, “What happened before the universe?” There very simply is no such thing as “before the universe.”