Starboard wrote:
First I'd like to state that what I am going to describe will be
described from a perspective that did not exist. I state the obvious
only because earlier, Greg shot me down for my metaphor about a guy
watching the big bang expand. He quickly stated that such a condition
was impossible. Of course I knew that I was only trying to conduct
a little thought experiment. Much the same, the analogy of the
balloon. After all, people cannot exist as 2D creatures right? That's
the equivalent of starting a metaphor with, "assume a cow is
spherical."

I think you need to stop being so stuck on your own view and instead try
to understand the one people are presenting you with. Please try to let
go of your preconceptions. A good popular book on cosmology might help
a lot. As you read it, come back here and ask questions to clarify things.

To answer your question above, the 2D world is an analogy. Don't
confuse this with a model of the universe--it isn't. It's just an
analogy meant to explain a concept. It is *not* the same as your cow
assumption!

As a 3D being you understand the world in 3 dimensions. But what if
there are more dimensions than you can perceive? What would that look
like? The answer is that you'd observe some odd things about the
universe--things that don't easily fit into your 3D view, like a
universe that expands away from any point within it, and has no center.

The 2D analogy is there merely as a means of investigating how more
dimensions than can be sensed can produce a universe with some of these
odd characteristics. You have to imagine a 2D being who knows nothing
beyond the surface of the balloon. The entire universe is the surface
only. So when the balloon is blown up, where is the center? The answer
is twofold: for the 2D being it has no center. But for you as a 3D
being you can see that the center lies in a dimension beyond that of the
surface of the balloon. What is obvious to the 3D being is not apparent
at all to the 2D being. Her only hope is to note some odd things about
her universe and postulate more dimensions to explain them.

Try to imagine this analogy from the point of view of the 2D being.
Think about questions like, what would they observe if someone from
outside blew up the balloon? If they started out in one direction and
traveled far enough, they would come back to where they started. That
would seem like magic. So how would they explain that scientifically?
But please keep in mind that the universe is NOT the surface of a
balloon. Again, it is the concept of what more dimensions than can be
perceived might look like that is important. Once that concept is
understood, then understand that in our own universe there are some
weird things that can't easily be explained in 3D. But postulating more
dimensions explains them neatly.

Greg

--
Greg Crinklaw
Astronomical Software Developer
Cloudcroft, New Mexico, USA (33N, 106W, 2700m)

SkyTools: http://www.skyhound.com/cs.html
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