Cosmological Constant Not Fine Tuned For Life

eldavojohn writes "A common argument one might encounter in intelligent design or the arduous process of resolving science with religion is that the physical constants of our world are fine tuned for life by some creator or designer. A University of Alberta theoretical physicist claims quite the opposite when it comes to the cosmological constant. His paper says that our ever expanding universe has a positive cosmological constant and he explains that the optimum cosmological constant for maximizing the chances of life in the universe would be slightly negative: 'any positive value of the constant would tend to decrease the fraction of matter that forms into galaxies, reducing the amount available for life. Therefore the measured value of the cosmological constant, which is positive, is evidence against the idea that the constants have been fine-tuned for life.'"

More galaxies would sterilize planets

[Raffaello]

The author of the linked study appears not to have considered that a universe more dense with galaxies would be a universe with many more planet-sterilizing gamma ray bursts [wikipedia.org], which would not be terribly conducive to life.

And here I thought...

[Empiric]

...you can't argue with success.

Known attempts at permutations of physical constants: 1
Success at creating intelligent life: 1

Of course, one could never argue against the line of reasoning suggested by the summary--whatever degree of life exists, arbitrarily declare there should be "more", and conjecture (yes, it's sheer conjecture--the actual results from modifying the cosmological constant would require far more calculation of than is provided) something else would have made it "better".

Personally, though I'm used to having my code second-guessed, they'd have to come up with a much better criticism than this...

Re:Any need for this?

[Burnhard]

Well, you can't prove a negative ("it wasn't designed"), can you? So the onus is on those who say it was to demonstrate that it must have been. Clearly in the space of all possible universes the anthropic principle rules.

Yes, Falsifiability

[eldavojohn]

Doesn't the Anthropic Principle [wikipedia.org] adequately deal with this issue in any case?

From the paper I linked in the summary:

Perhaps a more common view among physicists today is the idea that there is a multiverse with a wide range of values for the constants of physics, and by the selection principle of observership (the weak anthropic principle), we find ourselves in the part of the multiverse where life is possible and/or relatively common (at least compared to other parts of the multiverse) [7]. However, there is still considerable controversy over whether such a multiverse that would be necessary for this explanation really exists.

And then later the author says (calling this the 'third view'):

The third view, of observer selection within a multiverse, is hard to prove or disprove directly, since it appears very difficult to obtain direct information about other possible parts of a multiverse. However, if a simple theory were developed that gives good statistical explanations for what we do observe and that also predicts a multiverse that we cannot directly observe, such a theory could become highly convincing (analogous to the prediction by general relativity of very high curvature in black-hole interior regions that cannot be directly observed).

I believe the intent of this paper was to directly address the claims instead of using the weak anthropic principle. More importantly, his argument is falsifiable (that coveted trait in the scientific process) whereby the other three views are not at this time. As other posters have pointed out [slashdot.org] we can now attempt to reason out this theory further.

Re:More galaxies would sterilize planets

[KovaaK]

Even though BitZstream is using quite a few flame inducing words, he does have a point. A quick google suggests that we've identified life on Earth that uses gamma rays for energy. This [scienceagogo.com] was one of the examples I found by searching...

Re:Not the best of all possible worlds

[Burnhard]

Another objection is also the empirical evidence we're able to collect. For example, in 100,000,000,000 years time, the expansion of the Universe will mean that any future civilisation will look out into the sky and only see the Milky Way (stars will still exist then). There will be no evidence of a "big bang", inflation (the cosmic microwave background will have gone) and no evidence that other galaxies exist or have ever existed. Such a civilisation would not even think of dark matter, dark energy, dark flow, or anything else we need to cobble theory to observation.

I wonder what is missing from the picture now that would otherwise cause us to question and change our understanding of reality? Probably quite a lot!