Cosmologic philosophy: fine tuning or not? (Introduction)

by David Turell , Thursday, January 19, 2017, 18:44 (2865 days ago) @ David Turell

This physicist says it doesn't exist:

http://nautil.us/issue/44/luck/the-not_so_fine-tuning-of-the-universe?utm_source=Nautil...

"Over the past several decades, many scientists have argued that, had the laws of physics been even slightly different, the cosmos would have been devoid of complex structures. In parallel, cosmologists have come to realize that our universe may be only one component of the multiverse, a vast collection of universes that makes up a much larger region of spacetime. The existence of other universes provides an appealing explanation for the apparent fine-tuning of the laws of physics. These laws vary from universe to universe, and we live in a universe that allows for observers because we couldn’t live anywhere else.

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"But in fact the fine-tuning has never been rigorously demonstrated. We do not really know what laws of physics are necessary for the development of astrophysical structures, which are in turn necessary for the development of life. Recent work on stellar evolution, nuclear astrophysics, and structure formation suggest that the case for fine-tuning is less compelling than previously thought. A wide variety of possible universes could support life. Our universe is not as special as it might seem.

***

"Putting it all together, the strengths of the fundamental forces can vary by several orders of magnitude and still allow planets and stars to satisfy all the constraints (as illustrated in the figure below). The forces are not nearly as finely tuned as many scientists think.

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:physicist Fred Hoyle predicted in 1953 that the carbon nucleus has to have a resonant state at a specific energy, as if it were a little bell that rang with a certain tone. Because of this resonance, the reaction rates for carbon production are much larger than they would be otherwise—large enough to explain the abundance of carbon found in our universe. The resonance was later measured in the laboratory at the predicted energy level.

"The worry is that, in other universes, with alternate strengths of the forces, the energy of this resonance could be different, and stars would not produce enough carbon. Carbon production is compromised if the energy level is changed by more than about 4 percent. This issue is sometimes called the triple-alpha fine-tuning problem.

"Fortunately, this problem has a simple solution. What nuclear physics takes away, it also gives. Suppose nuclear physics did change by enough to neutralize the carbon resonance. Among the possible changes of this magnitude, about half would have the side effect of making beryllium stable, so the loss of the resonance would become irrelevant. In such alternate universes, carbon would be produced in the more logical manner of adding together alpha particles one at a time. Helium could fuse into beryllium, which could then react with additional alpha particles to make carbon. There is no fine-tuning problem after all.

(Here I skip other aspects of his argument since our space is not large enough. I suggest reading them.)

"In short, the parameters of our universe could have varied by large factors and still allowed for working stars and potentially habitable planets. The force of gravity could have been 1,000 times stronger or 1 billion times weaker, and stars would still function as long-lived nuclear burning engines. The electromagnetic force could have been stronger or weaker by factors of 100. Nuclear reaction rates could have varied over many orders of magnitude. Alternative stellar physics could have produced the heavy elements that make up the basic raw material for planets and people. Clearly, the parameters that determine stellar structure and evolution are not overly fine-tuned.

"Given that our universe does not seem to be particularly fine-tuned, can we still say that our universe is the best one for life to develop? Our current understanding suggests that the answer is no. One can readily envision a universe that is friendlier to life and perhaps more logical. A universe with stronger initial density fluctuations would make denser galaxies, which could support more habitable planets than our own. A universe with stable beryllium would have straightforward channels available for carbon production and would not need the complication of the triple-alpha process. Although these issues are still being explored, we can already say that universes have many pathways for the development of complexity and biology, and some could be even more favorable for life than our own. In light of these generalizations, astrophysicists need to reexamine the possible implications of the multiverse, including the degree of fine-tuning in our universe."

Comment: This is a minority opinion. I don't have enough knowledge to refute him; the article is filled with if's, but should be read.