why you owe your existence to quantum mechanics
When you're trying to start carbon-based life, not just any carbon isotope will do and the one you need wouldn't even exist without a quirk of quantum mechanics.
Carbon is a great element for kick-starting life thanks to its uncanny ability to form reactive, but still stable molecules perfect for creating proteins, amino acids, and even the backbone of DNA and RNA, or their functional equivalents. And yet, according to those who argue that the reason we exist is that the universe is somehow fine-tuned for us, or that life exists as a random, one in a trillion chance, it shouldn’t even be here. You see, when the first stars started fusing hydrogen into helium-4 deep in their searing cores, the resulting helium atoms should have combined into beryllium-8 which decays so quickly that there should have been virtually no chance for another helium atom to combine with it to form carbon-12, which accounts for 98.9% of all carbon in the known universe and makes life possible. According to astronomer Fred Hoyle, whose misuse of the anthropic principle has been used to justify many an anti-evolutionary screed, since carbon based life exists, there must be a mechanism by which this beryllium bottleneck is resolved and the clue to this mechanism must lie in the conditions under which the star fuses helium.
You see, when atoms fuse into a new element, the newly formed nucleus has to be at one of its natural, stable energy levels, otherwise the combination of the protons’ and neutrons’ energies, as well as the energy of their kinetic motion will prevent the fusion. Hoyle’s insight was than any new carbon atom must have had a resonance with the process by which a beryllium and helium atom would combine, which would exert just enough energy to slow down the decay rate for the reaction with a passing helium-4 atom to happen, so the natural energy level of the result would sustain a stable carbon-12 nucleus. Imagine rolling magnetic spheres down a hill, and as these magnets roll, they collide. Some will hit each other with just enough energy to keep rolling as a single unit and absorb new spheres they run into, others combine, then break apart, or just roll on their own. The angle, the force of impact, and the speed and masses of the spheres all have to be right for them to join, and when they do, they’ll have to stay that way long enough to settle down. This is quantum resonance in a nutshell, and it’s what made carbon-12 possible.
But while this is all well and good, especially for us carbon based lifeforms, where does Hoyle’s discovery leave us in regards to the question of whether the universe was fine-tuned for life? If we assume that only carbon based life is possible, and that the only life that could exist is what exists today, the argument makes sense. However those assumptions don’t. Even if there was no quantum resonance between helium-4, beryllium-8, and carbon-12 in the earliest stars from which the first atoms of organic molecules were spawned, the first stars were massive and it’s a reasonable guess that when they went supernova, they would have created carbon, silicon, and metals like aluminium and titanium. All four elements can be useful in creating molecules which can form the chemical backbones of living organisms. In fact, it’s entirely possible that we could one day find alien life based on silicon and that in some corner of the galaxy there are microbes with genomes wound around a titanium scaffold. Life does not have to exist as we know it, and only as we know it. We didn’t have to exist either, it’s just lucky for us that we did.
When creationists try to come up with the probability that life exactly the way we understand, or have at least observed to exist, came out the way it has, against all other probabilities, they are bound to get ridiculous odds against us being here. But what they’re really doing is calculating a probability of a reaction for reaction, mutation for mutation, event for event, repeat of the entire history of life on Earth, all 4 billion years of it, based on the self-absorbed and faulty assumption that because we’re here, there must a reason why that’s the case. The idea that there’s no real predisposition towards modern humans evolving in North Africa, or that life could exist if there’s no abundant carbon-12 to help bind its molecules is just something they cannot accept because the notion that our universe created us by accident and we can be gone in the blink of a cosmic eye to be replaced by something unlike ourselves in every way, is just too scary for them. They simply don’t know how to deal with not feeling like they are somehow special or that nature isn’t really interested in whether they exist or not, just like it hadn’t for at least 13.8 billion years…