By now, anyone who has had discussions about scientific evidence for the existence of God knows about the fine-tuning argument. In a nutshell, if the fundamental constants and quantities given in the Big Bang were even slightly other than they are, then the universe itself would not be hospitable for complex, embodied intelligent life.

Here is an article from The New Atlantis written by Australian cosmologist Luke Barnes.

Excerpt:

Today, our deepest understanding of the laws of nature is summarized in a set of equations. Using these equations, we can make very precise calculations of the most elementary physical phenomena, calculations that are confirmed by experimental evidence. But to make these predictions, we have to plug in some numbers that cannot themselves be calculated but are derived from measurements of some of the most basic features of the physical universe. These numbers specify such crucial quantities as the masses of fundamental particles and the strengths of their mutual interactions. After extensive experiments under all manner of conditions, physicists have found that these numbers appear not to change in different times and places, so they are called the fundamental constants of nature.

[…]A universe that has just small tweaks in the fundamental constants might not have any of the chemical bonds that give us molecules, so say farewell to DNA, and also to rocks, water, and planets. Other tweaks could make the formation of stars or even atoms impossible. And with some values for the physical constants, the universe would have flickered out of existence in a fraction of a second. That the constants are all arranged in what is, mathematically speaking, the very improbable combination that makes our grand, complex, life-bearing universe possible is what physicists mean when they talk about the “fine-tuning” of the universe for life.

Let’s look at an example – the strong force. Not only must the strong force be fine-tuned so we have both hydrogen and helium, but the ratio of the strong force must also be fine-tuned with the fine structure constant.

Barnes writes:

The strong nuclear force, for example, is the glue that holds protons and neutrons together in the nuclei of atoms. If, in a hypothetical universe, it is too weak, then nuclei are not stable and the periodic table disappears again. If it is too strong, then the intense heat of the early universe could convert all hydrogen into helium — meaning that there could be no water, and that 99.97 percent of the 24 million carbon compounds we have discovered would be impossible, too. And, as the chart to the right shows, the forces, like the masses, must be in the right balance. If the electromagnetic force, which is responsible for the attraction and repulsion of charged particles, is too strong or too weak compared to the strong nuclear force, anything from stars to chemical compounds would be impossible.

Here’s the chart he’s referencing:

As you can see from the chart, most of the values that the constants could take would make complex, embodied intelligent life impossible.

We need carbon (carbon-based life) because they form the basis of the components of life chemistry, e.g. proteins, sugars, etc. We need hydrogen for water. We need chemical reactions for obvious reasons. We need the light from the stars to support plant and animal life on the surface of a planet. And so on. In almost every case where you change the values of these constants and quantities and ratios from what they are, you will end up with a universe that does not support life. Not just life as we know it, but life of any conceivable kind under these laws of physics. And we don’t have any alternative laws of physics in this universe.

By the way, just to show you how mainstream these examples of fine-tuning are, I thought I would link to a source that you’re all going to be familiar with: The New Scientist.

The fine-tuning of the force of gravity

So here is an article from the New Scientist about a different constant that also has to be fine-tuned for life: the force of gravity.

Excerpt:

The feebleness of gravity is something we should be grateful for. If it were a tiny bit stronger, none of us would be here to scoff at its puny nature.

The moment of the universe‘s birth created both matter and an expanding space-time in which this matter could exist. While gravity pulled the matter together, the expansion of space drew particles of matter apart – and the further apart they drifted, the weaker their mutual attraction became.

It turns out that the struggle between these two was balanced on a knife-edge. If the expansion of space had overwhelmed the pull of gravity in the newborn universe, stars, galaxies and humans would never have been able to form. If, on the other hand, gravity had been much stronger, stars and galaxies might have formed, but they would have quickly collapsed in on themselves and each other. What’s more, the gravitational distortion of space-time would have folded up the universe in a big crunch. Our cosmic history could have been over by now.

Only the middle ground, where the expansion and the gravitational strength balance to within 1 part in 10¹⁵ at 1 second after the big bang, allows life to form.

Notice how the article also mentioned “the universe’s birth”, which is part of mainstream science.

When I’m writing to you about things like the origin of the universe, or the cosmic fine-tuning, I’m not talking to you about things that pastors found in the Bible. These discoveries are known and accepted by mainstream scientists. It’s amazing that people are constructing their worldviews without having to account for the birth of the universe and this cosmic fine-tuning. We all, as rational individuals, have to bound our view of the universe with the findings of science. Right now, those findings support the existence of a Creator and a Designer. So why am I seeing so many atheists who are just plain ignorant about these facts? Maybe we should tell them about this evidence. Maybe we should ask them why they don’t account for scientific evidence when forming their beliefs.

Positive arguments for Christian theism

• The kalam cosmological argument and the Big Bang theory
• The fine-tuning argument from cosmological constants and quantities
• The origin of life, part 1 of 2: the building blocks of life
• The origin of life, part 2 of 2: biological information
• The sudden origin of phyla in the Cambrian explosion
• Galactic habitable zones and circumstellar habitable zones
• Irreducible complexity in molecular machines
• The creative limits of natural selection and random mutation
• Angus Menuge’s ontological argument from reason
• Alvin Plantinga’s epistemological argument from reason
• William Lane Craig’s moral argument
• The unexpected applicability of mathematics to nature
• Arguments and scientific evidence for non-physical minds