In recent days, there has been a considerable stir in the blogosphere, as prof Don Page of the University of Alberta has issued two papers and a slide show that purport to show the death of — or at least significant evidence against — the fine-tuning cosmological argument. (Cf here and here at UD. [NB: A 101-level summary and context for the fine-tuning argument, with onward links is here. A fairly impressive compendium of articles, links and videos on fine-tuning is here. Video summary is here, from that compendium. (Privileged Planet at Amazon)])
However, an examination of the shorter of the two papers by the professor, will show that he has apparently overlooked a logical subtlety. He has in fact only argued that there may be a second, fine-tuned range of possible values for the cosmological constant. This may be seen from p. 5 of that paper:
. . . with the cosmological constant being the negative of the value for the MUM that makes it have present age
t0 = H0^- 1 = 10^8years/alpha, the total lifetime of the anti-MUM model is 2.44t0 = 33:4 Gyr.
Values of [L] more negative than this would presumably reduce the amount of life per baryon that has condensed into galaxies more than the increase in the fraction of baryons that condense into galaxies in the first place, so I would suspect that the value of the cosmological constant that maximizes the fraction of baryons becoming life is between zero and – LO ~ 3.5 * 10^- 122, with a somewhat lower magnitude than the observed value but with the opposite sign. [Emphases added, and substitutes made for symbols that give trouble in browsers.]
Plainly, though, if one is proposing a range of values that is constrained to within several parts in 10^-122, one is discussing a fairly fine-tuned figure.
Just, you are arguing for a second possible locus of fine-tuning on the other side of zero.
(And, that would still be so even if the new range were 0 to minus several parts in 10^-2 [a few percent], not minus several parts in 10^-122 [a few percent of a trillionth of a trillionth of . . . ten times over]. Several parts in a trillion is rather roughly comparable to the ratio of the size of a bacterium to twice the length of Florida or the lengths of Cuba or Honshu in Japan or Cape York in Australia or Great Britain or Italy )
I take liberty to scoop out and highlight my response in Dr Torley’s thread, but first let me discuss the issue of the Multiverse by citing John Leslie’s famous analogy of the fly on the wall from his classic Our Place in the Cosmos:
. . . the need for such explanations [of our evidently fine-tuned cosmos set to an operating point favourable to Carbon-chemistry, cell based intelligent life] does not depend on any estimate of how many universes would be observer-permitting, out of the entire field of possible universes.
Claiming that our universe is ‘fine tuned for observers’, we base our claim on how life’s evolution would apparently have been rendered utterly impossible by comparatively minor alterations in physical force strengths, elementary particle masses and so forth. There is no need for us to ask whether very great alterations in these affairs would have rendered it fully possible once more, let alone whether physical worlds conforming to very different laws could have been observer-permitting without being in any way fine tuned.
Here it can be useful to think of a fly on a wall, surrounded by an empty region. A bullet hits the fly Two explanations suggest themselves. Perhaps many bullets are hitting the wall or perhaps a marksman fired the bullet. There is no need to ask whether distant areas of the wall, or other quite different walls, are covered with flies so that more or less any bullet striking there would have hit one. The important point is that the local area contains just the one fly. . . . [Emphases and paragraphing added.]
In short, so long as there is a local sensitivity in the life-permitting cluster of parameters, that needs to be adequately explained.
In addition, a multiverse model has to be able to explain the existence of a multiverse set up so that it will search such a small domain sufficiently well that it is likely to capture the fine-tuned life-permitting set, rather than the equivalent of the badly set-up bread making machine that turns out burned hockey-pucks or half-baked doughy messes.
That too, arguably requires fine-tuning.
Or, as Robin Collins so memorably put it:
Suppose we went on a mission to Mars, and found a domed structure in which everything was set up just right for life to exist. The temperature, for example, was set around 70 °F and the humidity was at 50%; moreover, there was an oxygen recycling system, an energy gathering system, and a whole system for the production of food. Put simply, the domed structure appeared to be a fully functioning biosphere. What conclusion would we draw from finding this structure? Would we draw the conclusion that it just happened to form by chance? Certainly not. Instead, we would unanimously conclude that it was designed by some intelligent being. Why would we draw this conclusion? Because an intelligent designer appears to be the only plausible explanation for the existence of the structure. That is, the only alternative explanation we can think of–that the structure was formed by some natural process–seems extremely unlikely. Of course, it is possible that, for example, through some volcanic eruption various metals and other compounds could have formed, and then separated out in just the right way to produce the “biosphere,” but such a scenario strikes us as extraordinarily unlikely, thus making this alternative explanation unbelievable.
The universe is analogous to such a “biosphere,” according to recent findings in physics . . . . Scientists call this extraordinary balancing of the parameters of physics and the initial conditions of the universe the “fine-tuning of the cosmos” . . . For example, theoretical physicist and popular science writer Paul Davies–whose early writings were not particularly sympathetic to theism–claims that with regard to basic structure of the universe, “the impression of design is overwhelming” (Davies, 1988, p. 203) . . .
The responses in Dr Torley’s thread follow: