The Fine-Tuned Universe:
An Elegant Handiwork
“This most beautiful system of the sun, planets, and comets, could only proceed from the counsel and dominion of an intelligent and powerful being.”
— Isaac Newton (1643–1727)
By Chris and the Editorial Staff
Six Constants
Events such as the Eucharistic Miracles and the Resurrection are backed by evidence showing that the world is not governed by nature alone. What can we say about nature itself? Is it the product of chance, or was it “crafted” with you — yes, you who are reading this sentence right now – in mind?
In 197 AD, the Roman writer Minucius Felix described the universe as follows in Octavius:
Now if, on entering any house, you should behold everything refined, well-arranged, and adorned, assuredly you would believe that a master presided over it, and that he himself was much better than all those excellent things. So in this house of the world, when you see its providence, order, and law in the heavens and on earth, believe that there is a Lord and Parent of the universe far more glorious than the stars themselves, and the parts of the whole world.
British cosmologist and astrophysicist Martin Rees, in his book Just Six Numbers, discusses six dimensionless physical constants that, according to our current understanding, shape our universe. These numbers describe fundamental properties and quantities in physics that determine everything from the size and shape of galaxies to the possibilities for life on Earth. If any of these numbers were different, even slightly, the universe as we know it wouldn't exist.
N |
(~1036) |
This is the ratio of the strength of electromagnetism to the strength of gravity for a pair of protons. It's essentially a measure of the relative strengths of the two fundamental forces: gravity, which holds planets, stars, and galaxies together, and electromagnetism, which is responsible for light and is the force acting in the smaller scale of atoms. If N were significantly smaller, only a small and short-lived universe could exist; Rees notes “no creatures could grow larger than insects, and there would be no time for biological evolution.” |
ε |
(0.007) |
Defined as the fraction of mass energy converted to new energy when hydrogen fuses into helium. It determines how stars burn and how all the atoms of the periodic table were cooked inside the stars. Rees believes that if this constant were above 0.008, no hydrogen would exist. However, some physicists disagree and believe that this constant should be replaced by αs (~0.1179), the strong force coupling constant; substantial hydrogen remains as long as this constant doesn’t increase by more than 50%. |
Ω |
(~1) |
Represents the amount of matter in the universe. If Ω were very different, the universe could not have survived for billions of years in a form hospitable to life. A value greater than one would mean the universe would collapse back on itself, a value less than one would imply too little matter for galaxies to form. A value near one is critical for the formation of galaxies and stars and hence life as we know it. Rees notes, “The initial expansion speed seems to have been finely tuned.” |
λ |
(~0.7) |
Represents the cosmological constant, a measure of the repulsive "dark energy" that is causing the universe's expansion to accelerate. If λ were significantly larger, the universe would have expanded too rapidly for galaxies and stars to form. |
Q |
(~10-5) |
Pertains to the initial irregularities in the universe's mass distribution. A smaller Q would result in a universe forever barren of anything complex; a larger one would result in a violent universe with no galaxies at all. |
D |
(3) |
The number of spatial dimensions in our world. In a universe with more than three dimensions, gravity would not fall off with distance as it does in our universe, likely leading to unstable planetary orbits. In a universe with fewer than three dimensions, many complex structures (like our brains) would not be possible. |
Anthropic Principle
One common response to the fine-tuning problem is the anthropic principle, which states that we shouldn’t be surprised to find ourselves in a universe that allows for our existence since we wouldn’t be around to observe a universe that wasn’t conducive to our existence.
Philosopher John Leslie counters this with the following analogy, retold by Dr. Francis Collins (former head of the Human Genome Project and the National Institutes of Health):
In this parable, an individual faces a firing squad, and fifty expert marksmen aim their rifles to carry out the deed. The order is given, the shots ring out, and yet somehow all the bullets miss and the condemned individual walks away unscathed.
How could such a remarkable event be explained? Leslie suggests that there are two possible alternatives ... In the first place, there may have been thousands of executions being carried out in that same day, and even the best marksman will occasionally miss. So the odds just happen to be in favor of this one individual, and all fifty of the marksmen fail to hit the target. The other option is that something more directed is going on, and the apparent poor aim of the fifty experts was actually intentional. Which seems more plausible? (Collins p. 77)
While the anthropic principle points out that there is a limited range of outcomes that can be observed in a universe that has the characteristics to support intelligent life, it is an unsatisfying answer to how our fine-tuned universe came to be despite the infinitesimal odds. If something unlikely happens, whether it’s 50 marksmen all missing their target or the far more improbable existence of our universe, it’s reasonable to look for a reason why.
Multiverse Theory
Stephen Hawking proposed one solution: Our universe is just one among a potentially infinite number of universes, each with different physical constants. While this multiverse theory could explain the existence of our universe, it suffers from a lack of evidence. Sir Penrose, the aforementioned Nobel laureate who collaborated extensively with Hawking, said the following about Hawking’s use of the multiverse theory and the related M-Theory in The Grand Design:
It’s overused, and this is a place where it is overused. It’s an excuse for not having a good theory.
…
The book is a bit misleading. It gives you this impression of a theory that is going to explain everything; it’s nothing of the sort. It’s not even a theory.
Shortly before he passed away, Hawking acknowledged the following in his 2018 paper A Smooth Exit from Eternal Inflation?:
We are not down to a single, unique universe, but our findings imply a significant reduction of the multiverse, to a much smaller range of possible universes.
Referring to this paper, British author and professor Philip Goff wrote in the Guardian:
The problem is that the less variety there is among the universes, the less capable the multiverse hypothesis is of explaining fine-tuning. If there is a huge amount of variation in the laws across the multiverse, it is not so surprising that one of the universes would happen to have fine-tuned laws. But if all of the universes have exactly the same laws—as in Hawking and Hertog’s proposal—the problem returns, as we now need an explanation of why the single set of laws that govern the entire multiverse is fine-tuned.
…
There is still hope for a scientific account of fine-tuning. However, by ruling out one of the two scientifically credible options for doing this, Hawking and Hertog have slightly strengthened the alternative explanation in terms of God. It is ironic that the atheist Hawking should, in his final contribution to the science, make God’s existence less improbable.