Max Tegmark's library: Q

This work was covered by New Scientist in November 1997 and by Sky & Telescope in February 1998 (articles here).

Figure 1: How altering Q changes structure formation

Please click here to get 300K postscript file with the paper. If you want a color transparency with the figure above, just print page 8. Click here if you are interested in other research of mine. 

Why is the CMB fluctuation level 10-5?


Max Tegmark, Martin Rees


We explore the qualitative changes that would occur if the amplitude Q ~ 10-5 of cosmological density fluctuations were different. If is less than about 10-6 , the cosmological objects that form would have so low virial temperatures that they may be unable to cool and form stars, and would be so loosely bound that even if they could produce a supernova explosion, they might be unable to retain the heavy elements necessary for planetary life. If Q is greater than about 10-4, dense supermassive galaxies would form, and biological evolution could be marred by short disruption timescales for planetary orbits. If Q were still larger, most bound systems would collapse directly to supermassive black holes. These constraints on Q can be expressed in terms of fundamental constants alone, and depend only on the electromagnetic and gravitational coupling constants, the electron-proton mass ratio and the matter-to-photon ratio. We discuss the implications for inflation and defect models, and note that the recent anthropic upper bounds on the cosmological constant Lambda would be invalid if both Q and Lambda could vary and there were no anthropic constraints on Q. The same applies to anthropic bounds on the curvature parameter Omega.

Reference info:

ApJ, 499, 526-532 (1998), astro-ph/9709058

Online references:

This site also contains the latest (non-astro/ph) versions of some papers that are referenced in the text; Tegmark, Silk & Evrard 1993, Tegmark et al 1997, Tegmark 1997.