The problem is with our brains.
What problem you ask?
Over the last month I have encountered several posters who seem to reject modern theories of cosmology without understanding them at all. I have made several replies, here, and here, but I think a broader approach may be valuable.
If you are already intimately familiar with Big Bang cosmology you may find this diary very simple. This is not a detailed analysis, but rather a primer on how to conceptualize these counter-intuitive ideas. The problem, as I have stated, is with our brains.
The human mind develops according to the stimuli it receives. From the instant we are born our senses begin transmitting data to our brains, and then we attempt to categorize and understand the information. This naturally leads us - over time - to have a very good understanding of the human sized world. We experience things of medium size, over medium amounts of time, and that reality makes sense to us.
On the other hand, human beings can have a hard time comprehending things that occur on a vastly different scale. The human mind does not experience subatomic particles interacting in picoseconds, and therefore does not develop the tools to easily conceptualize such a thing. Likewise, stars and galaxies moving over billions of years are not easily visualized by medium-sized creatures.
This leads some people to reject scientifically supported ideas because they are so counter-intuitive. When it comes to Big Bang theory, it can be practically impossible for a human mind to visualize the extreme forces and rapidly changing scale. For those of us who are not dedicated cosmologists, a philosophical understanding of the theory must suffice. So let us begin.
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The comments that prompted this diary both contained a very simple question:
What came before the big bang?
The answer is that there is no before the big bang. That can be a difficult idea to grasp, and we're going to go through it step by step. First, we need a basic understanding of 10-dimensional astrophysics. To do this, I like to share a video by science writer Robert Bryanton.
Still with me?
If you followed what Rob was saying through the video, we can see that what we call time behaves just like another dimension of space. This is Einstein's "space-time". Just as a Flatlander could only experience 2-dimensional cross-sections of our 3-dimensional bodies, we can only naturally perceive 3-dimensional cross-sections of our universe in the fourth dimension. To understand the Big Bang, we need to recognize that time will be behaving like another dimension of space.
Now on to the bang.
The after-effects of the Big Bang can still be seen today - the universe is expanding. When cosmologists say "universe" we are discussing all of reality. The universe contains all space and we can observe that space expanding because we have landmarks: matter. By observing the relative position and movement of astronomical objects we can map the expansion of the universe.
Now, according to our map, if we were to travel back through the fourth dimension (time) towards the Big Bang, we would see the universe collapsing. If we followed it back far enough, we would see all of reality collapsed into a single point - called a singularity. With the universe in a singularity you could travel for eternity in any direction, and you would still be inside the point.
What is outside the point, you ask?
There is no outside the point. This is the idea that can be so hard to understand for human minds. If you visualize a point of light sitting in a black void you are doing it wrong. There is no black void. All ten dimensions of reality are rolled up into that point, and reality exists only on that scale. Remember that time is in there too, rolled up infinitely small.
Once we start moving through the fourth dimension away from the Big Bang, we see all of the dimensions grow larger. They expand with incredible speed, and drag matter and energy across the emerging open space. More than ten billion years later we arrive at the universe we live in today, roomy enough for thousands of galaxies and still expanding.
So we can see that the question about what came before the Big Bang makes no sense. Reality does not conform to our linear observations. We call our current position in the fourth dimension "now". Fourth dimensional points further away from the Big Bang are called the "future", while points closer to it are the "past". Once we go all the way back to the Big Bang there are no points closer to the beginning of the universe: there is no past.
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This is just a simple introduction, I vigorously encourage you to read more. There are some excellent books on the topic that go into much greater detail than this short diary. I would recommend Fabric of the Cosmos as a good next step.
I will be around for a while tonight working on my computer, so please leave any questions/comments/suggestions and I will respond.
Peace