Lubos Motl challenges Roger Penrose's critique of string theory

On May 2, 2006, at 12:14 PM, Lubos Motl wrote:

On Tue, 2 May 2006, Jack Sarfatti wrote:

Can anyone defend string theory against Roger Penrose's pulverizing attack in Chapter 31 of "The Road to Reality"?

Sure, every grad student can do it after the first semester of string theory.

Prof. Penrose is completely confused about basic things. Calabi-Yau compactifications are supersymmetric which trivially implies that they are stable. Moreover, all singularities on the moduli space of Calabi-Yau manifolds - corresponding to singular versions of the manifold (a conifold) - have smooth string theory physics around these points because of the existence of additional light states such as wrapped 3-branes. All of this has been understood in detail for more than 10 years. Prof. Penrose was clearly sleeping during that time. Best wishes, Lubos
______________________________________________________________________________
E-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/
eFax: +1-801/454-1858 work: +1-617/384-9488 home: +1-617/868-4487 (call)
Webs: http://schwinger.harvard.edu/~motl/ http://motls.blogspot.com/
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^