Why does classical string theory have only 9 dimensions?

[camcelve]

Why does classical string theory have only 9 dimensions?

[ydoaPs]

Classical string theory? o.O

[michel123456]

Because there are 9 letters in the word classical ?

[ajb]

When one quantises the superstring, that is apply the rules of quantum theory to the strings, does the condition that the theory be formulated on 9+1 dimensions become important. In any other dimensions the resulting quantum string theory is not well defined and inconsistent.

[michel123456]

When one quantises the superstring, that is apply the rules of quantum theory to the strings, does the condition that the theory be formulated on 9+1 dimensions become important. In any other dimensions the resulting quantum string theory is not well defined and inconsistent.

 

Oho, seriously now

9+1

Is that 3^2 dim of space + 1 of time?

[ajb]

Oho, seriously now

9+1

Is that 3^2 dim of space + 1 of time?

 

Yes, 9 space and one time, for superstrings.

 

String theory, as far as I know, is the only theory that predicts the number of dimensions it needs to be formulated in.

[ydoaPs]

Yes, 9 space and one time, for superstrings.

 

String theory, as far as I know, is the only theory that predicts the number of dimensions it needs to be formulated in.

I thought some from of loop quantum gravity predicted 4 dimensions, but I may be wrong.

[ajb]

I thought some from of loop quantum gravity predicted 4 dimensions, but I may be wrong.

 

 

I don't think that loop quantum gravity predicts 3+1 dimensions, but this is the number of dimensions it is usually formulated in. I am not sure about the status of including all the matter fields into loop quantum gravity in 3+1 dimensions.

[michel123456]

3^2 can be represented as if each dimension of space had 3 dimensions: length, width, height.

But since the width of one dimension is the length or width of the other, it becomes redundant. And there is no need for curled up dimensions.

 

Also

you can create length by extending a point over time. You can create width & height the same way: a point along time. So that all spatial dimensions can be constructed by a single point extending over time, in 3 directions. Or 9 directions minus 6 redundant.

Which products a spatial framework made from a point litterally exploding in time.