I'm interested in claims of the kind "the universe's fundamental constants were fine tuned with the goal of supporting intelligent life" and the question of how to assess how valid/crazy such claims are. One can collect various claims of the form "if constant X were changed to become >Y*X, then the universe would become unfriendly." Please list your favorites. I'd like to assemble a collection. But usually when I try to do that I get Y-values of, say, 10. Not 1.01, which would be a lot more impressive. There are certain Christians etc who enjoy collecting such claims, but some of them are misleading (and some are just completely wrong, but I'll ignore those). Two examples: "The neutron/proton mass ratio is about 1.001 and if it were >1.01 or <1 then life would be impossible." Really this is since the electron is 1836 times lighter than the proton, and perhaps one could argue if 1836 were <750 or >3000 the universe would be unfriendly, but that would be a factor-4-wide range, not factor<1.01-wide. "The 'Hoyle state' of carbon: the third-lowest energy state of the carbon-12 nucleus, with an energy of 7.656 MeV above the ground level. According to one calculation, if the state's energy were lower than 7.3 or greater than 7.9 MeV, insufficient carbon would exist to support life; furthermore, to explain the universe's abundance of carbon, the Hoyle state must be further tuned to a value between 7.596 and 7.716 MeV. A similar calculation, focusing on the underlying fundamental constants that give rise to various energy levels, concludes that the strong force must be tuned to a precision of at least 0.5%, and the electromagnetic force to a precision of at least 4%, to prevent either carbon production or oxygen production from dropping significantly." But S.Weinberg responds: The crucial thing that affects the production of carbon in stars is not the 7.65 MeV energy of the radioactive state of carbon above its normal state, but the 0.25 MeV energy of the radioactive state, an unstable composite of a beryllium 8 nucleus and a helium nucleus, above the energy of those nuclei at rest. This energy misses being too high for the production of carbon by a fractional amount of 0.05 MeV/0.25 MeV, or 20 percent, which is not such a close call after all. Weinberg seems to think the only really impressive fine tuning is the Einstein cosmical constant Lambda, which is not zero, but is about 121 orders of magnitude smaller than a naive guess would have been, perhaps due to an amazing almost-cancelation, albeit nobody understands it. It seems to me even a collection of examples with Y=10 each, still seems impressive if you have enough of them. Here is a quote by Martin Rees about this: "Suppose you are in front of a firing squad, and they all miss. You could say, 'Well, if they hadn't all missed, I wouldn't be here to worry about it.' But it is still something surprising, something that can't be easily explained. I think there is something there that needs explaining." Is there? -- Warren D. Smith http://RangeVoting.org <-- add your endorsement (by clicking "endorse" as 1st step)