Learn more physics!
Quest ce que la théorie M ET quel est sa relation avec la théorie des super cordes?
Pourquoi doit on nécessairement développer des théories a 9...10... ou 11 dimentions qui ne semblent avoir quun sens mathématique pour pouvoir unifié les forces fondamentales connues de lunivers physique.
- Jean Yves (age 50)
The distinction between M theory and the various string theories is
beyond our expertise. M theory is said to be a more general theory from
which the various string theories emerge as limits in certain parameter
The number of dimensions is set by the requirement that the
theories be renormalizable. That means that there has to be a way to
set parameters so that calculations do not all blow up to infinity when
one sums all of the effects. This constarint is even trickier in
quantum gravity than in other quantum theories. Any energetic event
deforms space time, which creates more events, further deformning
spacetime etc. Unless special conditions are met allowing cancellations
of most of the terms, the resulting infinite sequences of effects
cannot be made to converge. In 10 dimensions (time + 9 spatial ones)
string theories can converge. In M theories, which include
higher-dimensional constituents than strings, the number of dimensions
needed goes up by one.
Here I'm just passing along things I've heard, not things I understand.
(republished on 07/21/06)
Follow-up on this answer.