and then again maybe not!
Scott,
I would not have responded to this post at all under normal circumstances; however, you seem to be a pretty rational person and at the same time somewhat ignorant of the qualifications of those who post here. In essence, I suspect very strongly that you will not find anyone on this forum who can answer your questions decently. The world wide web is not really a field on which to find intellectual satisfaction; people who are serious about such issues communicate (for the most part) only with close friends in their own field. I am an old man and certainly not up to date on any of this stuff; however, I do have a good background in mathematics and physics. I am familiar with many of the aspects of mathematics which have influenced physicists in the past and can put forward my personal opinions on several of these issues. But, please, remember at all times that what I am saying is almost all opinion. I apologize in advance if, at any time, what I say presumes ignorance which is not present.
First, it is always nice to know the source of a word as it gives one an introduction to what was going through the minds of those who started it all off. What you bring up concerns thoughts about viewing things from a perspective of a higher dimensional space; both the advantages of such a perspective and the problems associated with the same sort of ideas.
Einstein's Theory of General Relativity brings in the idea that the physical universe actually has the characteristics of a non-Euclidean geometry. I would comment here that this is completely counter to Henri Poincareé's position that "one geometry can not be more true than another; it can only be more convenient." That is to say, Einstein's geometry is taken today as being "true" not as being "convenient".
At any rate, the success of General Relativity and curved space as a mechanism to explain things led physicists to "push the envelope" so to speak. Now the mathematics required to describe some things in higher dimensions turn out to be very similar to the mathematics needed to describe certain physical phenomena. Thus we are lead to the idea that the rules of the Universe are actually a consequence of higher dimensionality and the interactions which can occur in such a picture.
You are a biologist so you are familiar with the idea of membranes; well membranes can be seen as two dimensional surfaces which divide one region from another. In this "higher dimensional" space of course, we have "branes" of higher dimensionality and "branes" of particular geometrical structure (D-branes are apparently a kind of P-brane etc., etc.). You can check out
http://www.theory.caltech.edu/people/jhs/strings/index.html
if you want to. So, having branes in mind, it is put forth that our universe is actually the intersection (or collision if you will) of higher dimension branes in a suitably higher dimensional space. Let us say that such a picture (if you know enough math to deduce the consequences correctly) introduces the math they want to use to describe the phenomena they think they need to explain what they see (hypothesis built upon hypothesis until the mind boggles).
However, a subtle problematical thing happens in this picture. In order to fulfill their requirements, the physical Universe we see must have a higher dimension than the simple three you and I see. The question clearly arises as to why we are not aware of these higher dimensions? Well, if you accept Einstein's picture of curved space, maybe it is just so tightly curved that you can't see it! That solves the problem for me! How about you?
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* ***** Scott:
The other dimensions are smaller than the diameter of a proton. What does that mean? What are these dimensions a part of? Are we existing in them or are they just all around us? I don't know how to picture it!!
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They have to be smaller than the diameter of a proton or their existence would show up in our experiments (we could see them). So you can't picture it; is that any real problem? It's the mathematics that's important isn't it. All this geometric stuff is just continuation of Einstein's success. In science as in business, they always continue along the same lines until they eventually achieve bankruptcy.
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* ***** Scott:
I was hoping somebody could clear up these cosmological enigmas for me.
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If anybody ever clears it up for you, let me know. I would enjoy having it all cleared up for me too. Sorry if I sound like a cynical old man, it's just that I am a cynical old man!
Have fun -- Dick |