# the dimensions

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Hi

Just wondered if someone could explain to me the dimensions of the world. I only thought there were 4, but someone told me there were 9 or 12?! Is this true?

Thanks

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For most intents and purposes, there are 4. The three spatial dimensions, and time.

However, some current postulates require the existance of other dimensions, as part of what is called a Calibi-Yau space. These are usually referred to as being 'curled up', as they're pretty damn small.

As an example, consider an ant on a rope. If it goes forwards or backwards, it can (assuming an infinite rope) go on forever. If it goes left or right, it can only go a short distance before coming back on itself, as it walks around the rope. The curled up dimensions are like going round the outside of the rope.

Of course, that's only speculation at the current point in time.

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There are actually more than 9 or 12, the last I heard, there where arox. 26 known dimensions.

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Whoa...26?! I'd love to know what pupose they serve? Any ideas?

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Last I heard, it was 10 or 11 depending on which theory you are using. Where did 26 come from?

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no, it's been a couple of months since i read about them, but if you wish, i read about them in a past issue of the magazine scientific american.

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sure, Id love to hear more about them!

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i think it's about 3-4 months old

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thats fine, still (as always) willing to learn!

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well, i don't know, i just read it in a magazine with an article aboute extra dimensions that we don't see or sense in any way, so it's probably just theoretical, but, when did you hear about 10 or 11, it may be an older idea. it might also just be another theory.

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lol, I havnt been reading much on dimensions lately, but I was interested in it a while ago.

BTW- Im seeing a lot of Einstein icons here

(laghs)

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I got to hear a lecture from Michio Kaku at the National Science Bowl last year in D.C., where he gave a good analogy for understanding the theory of a multidimensional universe.

The number of dimensions is inconsequential, to me at least. The theory behind it is more important.

You can read that analogy at his website:

thank you

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I got to hear a lecture from Michio Kaku at the National Science Bowl last year in D.C.' date=' where he gave a good analogy for understanding the theory of a multidimensional universe.

The number of dimensions is inconsequential, to me at least. The theory behind it is more important.

You can read that analogy at his website:

Thats true

Sounds Cool!

yah

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string theory currently needs 10 or 11 depending on which one ur using (which is weird because they are all different versions of the same theory).

ok then

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If my memory don't plays tricks on me... i belive it was M-theory that needed 26 dimensions for it's utterly complicated math!

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i don't know the name of the theory, i just breifly read about it in a magazine, so i just read the article and the theory itself... so, i don't really know what it was titled.

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What issue # is it?

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There are actually more than 9 or 12, the last I heard, there where arox. 26 known dimensions.

"...To account for these strings, a theory called superstring theory postulates that space and time exist in ten dimensions. ......The current prevailing string theory, called M-Theory (5), came after what scientists refer to as the "second superstring revolution." It proposes an eleven-dimensional space that consists of objects with multiple dimensions called p-branes. One type of p-brane is the d-brane, which can be related to the end points of the strings. Another string theory postulates a twenty-six dimensional space (3). Yet another seeks to use a five-dimensional space to describe the universe. The mathematical principles and equations associated with these theories are all extremely complex and difficult for the average undergraduate to understand."

The above paragraph is extracted from an article by this gentleman:

Vikram Pattanayak

Biochemistry and Biophysics, University of Pennsylvania

at this web site

http://www.jyi.org/volumes/volume5/issue3/features/pattanayak.html

I love the last sentence of the extract!

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To say that there are 11 dimensions (or whatever number is fashionable at the moment) is a little bit misleading. Heterotic string theory conjectures that there are 10 and M-theory conjectures that there are 11. But string theory etc has never been tested by experiment, never mind confirmed.

As far as our experiments see, there are only 4 dimensions. In other words, 4 dimensions is sufficient to describe all observations, or to be more exact, one cannot describe these observations more reliably by using more than 4 dimensions.

This may all change soon though. There are some very interesting ideas of having extra dimensions with a rather low compacification scale. If this were the case, gravity could be weak not because the Planck scale is so high, but because it propagates in the extra dimensions. Then the true Planck scale could be as low as a (few) TeV, which is within reach of colliders currently being built. Who knows, we might be experimentally testing string theory in five years time, or even creating our very own black holes in our colliders....

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