M. Tegmark. (1997)cite arxiv:gr-qc/9702052Comment: Minor modifications to match published version. 5 pages. Color figures and related links at http://www.sns.ias.edu/~max/dimensions.html (faster from the US), from http://www.mpa-garching.mpg.de/~max/dimensions.html (faster from Europe) or from max@ias.edu.