New Miscellany: more on fine-tuning (General)

by David Turell , Sunday, February 16, 2025, 19:18 (18 days ago) @ David Turell

Fine-tuning

DAVID: [i]For the whole universe to exist all the factors must be fine-tuned, to exquisitely narrow points of accuracy. Earth's life allowing adjustments are a different issue entirely.[/i]
And:
DAVID: Apparently you weren't following the discussions thirty years ago. The whole universe exists because of the fine-tuning factors, about 20+ of them. It is all very sophisticated physics. "Universes" by John Leslie will explain it.

dhw: Apparently you have totally misunderstood the focus of the debate:

DAVID: No I haven't.

dhw: You have argued twice that fine-tuning applies to the existence of the universe, instead of to the existence of life in the universe! You even say the adjustments (= fine tuning) which have produced life on Earth are a different issue!
I offered you three quotes confirming the fact that “fine-tuning” refers to the existence of life, and not of the universe.

DAVID: The entire universe can only exist if the fine-tuning factors are correct. That is the fine-tuning understanding I use from thirty years ago, not confined to only our galaxy. Davies is correctly coming at it from a different viewpoint.

dhw: Your understanding of fine-tuning as referring to the existence of the universe simply means that if the universe was not as it is, it would not exist as it is! Not much of a revelation, is it? So please stop dodging! The discussion is on whether the universe is fine-tuned for life, and I am simply pointing out that although all the ingredients for life are of course present in the universe, the only instance we know of in which those ingredients plus all the necessary environmental conditions have come together to produce life is Planet Earth, which at most means that our galaxy is fine- tuned for life. It is the combination that makes for the “fine tuning” – not the mere existence of the materials. And so I suggest to you that unless life is found throughout the entire universe, we cannot say that the entire universe is fine-tuned for life. Now will you please explain why you disagree.

Reread above: This specific whole universe exists only because 20+ factors are fine-tuned. The same factors apply to the appearance of life, because if this universe varied the factors only a little. life could not appear. Thus fine-tuning is throughout the universe while life appeared so far only on Earth. We think life might be out there somewhere because the same factors are everywhere, so we discuss possible alien life.

Note this study on alien life:

https://phys.org/news/2025-02-planetary-evolution-favor-human-life.html

Humanity may not be extraordinary but rather the natural evolutionary outcome for our planet and likely others, according to a new model for how intelligent life developed on Earth.

The model, which upends the decades-old "hard steps" theory that intelligent life was an incredibly improbable event, suggests that maybe it wasn't all that hard or improbable. A team of researchers at Penn State, who led the work, said the new interpretation of humanity's origin increases the probability of intelligent life elsewhere in the universe.

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In the new study, a team of researchers that included astrophysicists and geobiologists argued that Earth's environment was initially inhospitable to many forms of life, and that key evolutionary steps only became possible when the global environment reached a "permissive" state.

For example, complex animal life requires a certain level of oxygen in the atmosphere, so the oxygenation of Earth's atmosphere through photosynthesizing microbes and bacteria was a natural evolutionary step for the planet, which created a window of opportunity for more recent life forms to develop, explained Dan Mills, postdoctoral researcher at The University of Munich and lead author on the paper.

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The researchers said they plan to test their alternative model, including questioning the unique status of the proposed evolutionary "hard steps." The recommended research projects are outlined in the current paper and include such work as searching the atmospheres of planets outside our solar system for biosignatures, like the presence of oxygen.

Comment: This study presumes fine-tuning for life is everywhere in the universe. Life can then appear in any spot that evolves life hospitability as it did on Earth. With universal fine-tuning life can be invited anywhere.