hi everyone,(adsbygoogle = window.adsbygoogle || []).push({});

i am no physicist so i only have a slight understanding of these matters.

I just finished reading Greene's "elegant universe" and i understood that in "classical" string theories there are 6 compactified dimensions along with our familiar 3 extended spacial dimensions + time.

From what Greene writes, M-theory (following supersimmetry/supergravity theories) adds a further compactified dimension which is different from the other ones because it is "embedded" in the strings themselves. I mean, if i understood correctly (which i doubt), the six compactified dimensions are "external" to the strings and they add further degrees of freedom to the strings'movements and vibrations. The seventh dimension is instead "embedded" in the strings, so that a string can become a 2-brane.

If the above is true, why then are we only adding one further dimension? given the fact that branes can have n dimensions, why the m-theory only adds one further compactified dimension and not n further dimensions?

Hope i made myself sufficiently clear, thanks for an answer,

matteo

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# Silly question about n.of dimensions in m-theory

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