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To be or not to be? Testing the fine-tuning of the universe for life


Hugh Ross reviews The Big Conversation between Luke Barnes & Sabine Hossenfelder, where they debated not just whether God explains fine-tuning, but whether fine-tuning even exists!

Is the universe fine-tuned for us?

Much of my life has been devoted to writing about the scientific evidence for God’s fine-tuning of the universe for human beings.  So, with great interest I watched the debate between Luke Barnes and Sabine Hossenfelder, moderated by Justin Brierley on Premier’s Unbelievable show.

Astrophysicist Barnes, a Christian, believes that God fine-tuned the universe for life, while Hossenfelder, a theoretical physicist, does not, nor does she believe that God’s existence can be hypothesized from science.

The basis for Hossenfelder’s claim is that we cannot alter the constants of physics to observe what would happen if these constants were different. We can observe only one universe in one particular state. She concludes that with a sample size of only one, we cannot draw conclusions about whether or not the universe was fine-tuned or about whether a Designer exists.

Barnes argued that although we cannot change the constants of physics, we can determine what effect(s) would result from any change to them. Physicists can show that even miniscule changes would be catastrophic for life.

I would add to Barnes point that because fine-tuning is observed on all cosmic size scales, not only on the scale of the entire universe, the sample size we are working with is much larger than one. We can observe the Laniakea super-galaxy cluster, the Virgo galaxy cluster, the Local Group, the Milky Way Galaxy, the Local Bubble, the Local Fluff, the solar system, the Sun, the Moon, and Earth, for example, and at these smaller size scales, the sample size expands from hundreds to quadrillions.

What makes the fine-tuning argument most compelling is that out of the thousands of super-galaxy clusters we can observe, only our Laniakea super-galaxy cluster has the precise features needed for the support of advanced life. We can observe many more galaxy clusters, but ours is the only one capable of sustaining advanced life. Likewise, our Local Group of galaxies is unique among observable galaxy groups in its life-supportive capacity. What’s more, only one galaxy out of millions, one star out of tens of millions, one planetary system out of 3,554, one planet out of 4,811, one moon out of 200+ observed possesses the features essential for advanced life not only to exist but also to endure.

On all these smaller cosmic size scales we can determine and observe what will happen if any one of the dozens of its life-essential characteristics were altered. In each case, even the tiniest changes would eradicate the possibility for advanced life.

Fine-Tuning for Microbes vs. Fine-Tuning for Humans

Scientists typically consider fine-tuning evidence only in the context of what is needed for a few microbes to survive in or on any cosmic body for a short time. The degree of fine-tuning required for microbes of sufficient abundance and diversity to survive for 3 billion years and, during that time, chemically transform an otherwise toxic planetary surface to one that is survivable would be exponentially greater.

The degree of fine-tuning necessary for a planet to support the equivalent of human beings for some tens of thousands of years would be far greater still. For billions of humans to exist at one time on one planet with technology so advanced as to allow for global communication would require a degree of fine-tuning too great to calculate. (See for details and documentation.)

Multiple Purposes

Fine-tuning required for life that can fulfill even one particular purpose, such as mere survival, seems powerful evidence for the existence and involvement of a Creator-Designer. Fine-tuning for life with a capacity to fulfill multiple purposes demands far more intentionality and precision.

Skeptics are mistaken in presuming that the only purpose for cosmic fine-tuning is to make a home where life is possible. The human experience demonstrates that life’s home allows not only for primitive life but also for an extremely broad diversity and abundance of life and makes possible the rapid development of global, technologically advanced civilization. That we humans are living at a unique time and place to observe and measure the entire history of the universe would seem to imply, reasonably, that the universe was designed for humans to make extensive scientific discoveries.

The Bible declares that the cosmic Fine-Tuner began planning for our existence here in this universe, as well as for a future beyond it, even before he created it. This declaration indicates that every significant component of the universe and every significant event in the universe’s history plays a role making it possible for billions of humans within a relatively brief time window to establish a personal relationship, a redemptive relationship, with the One who created all this and us. This implication is proving to be a successful tool in the quest to uncover additional evidences for fine-tuning.

In my books Why the Universe Is the Way It Is and Improbable Planet, I describe other discoveries that reveal multiple purposes—beneficial, redemptive purposes—for the large-scale and small-scale characteristics of nature’s realm. Based in my own and others’ observations, I anticipate that many more will be discovered.

Testable, Falsifiable, and Predictive

In a dialogue Brierley moderated between astrophysicist Paul Davies and me, I described the testable, falsifiable, predictive creation model under development at Reasons To Believe. Davies, who describes himself as agnostic, declared that if we have such a model, we deserve a place “at the table” with fellow science researchers.

In contradiction to Hossenfelder, I would assert that the notion of a fine-tuned universe holds predictive power and, therefore, the opportunity to guide scientific research. The discovery of one fine-tuned feature of the universe, the galaxy, the solar system, the Earth, etc., for the sake of advanced life often leads to the discovery of other fine-tuned features.

For example, astronomers have long recognized that a planet must orbit its host star at a narrowly specified distance for that planet to have the capacity to retain surface liquid water. The recognition that this liquid water habitable zone for advanced life is extremely narrow has prompted researchers to consider that Earth may well reside in other similarly fine-tuned planetary habitable zones. Over the past decade, astronomers have been discovering these habitable zones at the rate of about one per year. The list now stands at fourteen known such zones, such as the ultraviolet, tidal, astrosphere, and atmospheric electric field zones.

This alertness to potential design features led to the discovery that a single nearby massive moon orbiting a small planet is necessary to stabilize the rotation axis tilt (obliquity) of that planet sufficiently for advanced life to live and thrive on that planet. In the case of the Earth-Moon system, the Moon’s mass is at the upper end of the mass range that will produce stable obliquity.

Discovery that the Moon’s mass is so close to generating instability in Earth’s obliquity suggested the possibility other fine-tuned features dependent on the Moon’s precise mass. This follow-up research revealed that the Moon’s high mass and proximity to Earth and resultant exertion of tidal forces are responsible for slowing Earth’s rotation to the 24 hour/day rate that proves optimal for humanity—also at the precise moment when the Sun’s luminosity gained a level of stability that permits the existence of humans and human civilization on Earth.

The Moon’s mass and proximity to Earth must be fine-tuned for additional reasons, distinct from providing Earth’s just-right obliquity and rotation period. For example, the Moon must form in a hot enough state with sufficient mass and proximity to Earth (less than18 Earth radii distant) for the formation of a coupled magnetosphere (coupling of Earth’s magnetosphere with the Moon’s magnetosphere). Only the remarkable development of this early, strong coupled magnetosphere could prevent solar particle radiation from completely sputtering away Earth’s atmosphere and surface water.

Many more examples of the testability and predictability of what astronomers call “the anthropic principle” (the observation that the universe is fine-tuned for humans) have been descibed and documented in books and articles by astronomers, astrophysicists, and many other researchers in a variety of disciplines. Some of these include my own works and those of my colleagues at Reasons to Believe. (See The Creator and the Cosmos, 4th edition; Fit for a Purpose (release date October 2021), and Designed to the Core (release date March 2022).

God of the Gaps vs. No-God of the Gaps

Many skeptics have charged that to view the universe as fine-tuned for us is to commit the God-of-the-gaps fallacy. They assert theists simply insert God into scientific knowledge gaps and that when these gaps are closed by ongoing research, the evidence for fine-tuning will diminish and eventually evaporate.

This familiar assertion is as testable as the assertion that a Causal Agent/Fine-Tuner beyond the universe has crafted the universe for our existence. If fine-tuning is a fallacy strictly based on knowledge gaps, we would expect the evidence for precise anthropic designs to shrink, rather than grow, as research advances our knowledge. If a Fine-Tuner exists, we would anticipate that the more astronomers learn about the universe and all its components, the more evidence for this Agent will accumulate and grow exponentially stronger.

The scientific track record of the past eight decades shows that the evidence for fine-tuning by a Causal Agent has been rising dramatically with every passing year. My encouragement to those who remain skeptical about such fine-tuning is to put these two assertions to the test by observing the trajectory of scientific discoveries in the days, weeks, and months of the year ahead.

Hugh Ross is an astrophysicist and the President and Founder of Reasons To Believe.

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