WHY IS THE COSMIC MICROWAVE BACKGROUND FLUCTUATION LEVEL-10(-5)

We explore the qualitative changes that would occur if the amplitude Q similar to 10(-5) of cosmological density fluctuations were different . If Q less than or similar to 10(-6), the cosmological objects that f orm would have such low virial temperatures that they may be unable to cool and form stars, and they would be so loosely bound that even if they could produce a supernova explosion they might be unable to retai n the heavy elements necessary for planetary life. If Q greater than o r similar to 10(-4), dense supermassive galaxies would form, and biolo gical evolution could be marred by short disruption timescales for pla netary orbits. If Q were still larger, most bound systems would collap se 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 imp lications for inflation and defect models and note that the recent ant hropic upper bounds on the cosmological constant Lambda would be inval id if both Q and Lambda could vary and there were no anthropic constra ints on Q. The same applies to anthropic bounds on the curvature param eter Omega.