Fred Hoyle's "amazing fine tuning" regarding the energy of the excited state of the carbon atom at about 7.65 MeV above ground, was re-examined by H.Oberhummer, A.Csoto, H.Schlattl: "Fine-Tuning of Carbon Based Life in the Universe by Triple-Alpha Process in Red Giants," Science 289, 5476 (7 July 2000) 88-90. Nucl.Phys. A 688 (2001) 560-562 Nucl.Phys. A 689 (2001) 269-279 "The result is that even with a small change of 0.4% in the nucleon-nucleon interaction strength, carbon-based life appears to be impossible, since all the stars then would produce either almost solely carbon or oxygen, but could not produce both." They argue that Weinberg's analysis somewhat missed the point: if the level moves too much you get no carbon, only carbon and no oxygen, or only oxygen and no carbon. You have to be just right. Sounded cool, except largely retracted after further re-analysis including some of the same authors as before, H. Schlattl, A. Heger, H. Oberhummer, T. Rauscher, A. Csoto: Sensitivity of the C and O production on the 3-alpha rate, http://lanl.arxiv.org/abs/astro-ph/0307528 "when the evolution of the stars as a whole was followed for their entire life, in particular the low- and intermediate-mass stars show fine tuning of carbon and oxygen yields that is more complicated and far less spectacular than found in Paper I. Therefore, the anthropic significance of the 3alpha rate might be considerably less." Oops. Still later review: Ulf G. Meissner: Anthropic considerations in nuclear physics, Science Bulletin 60,1 (2015) 43-54. http://lanl.arxiv.org/abs/1409.2959 ...from which you might guess the latest claim is the Hoyle effect constrains the strong force to within a few-%-wide window, otherwise the universe will be lousy. Making this now all as clear as mud.