There is a just-right separation distance between them to foster the best possible chemistry. Put them either too close or too far apart and their capacity to interact with one another will sharply diminish. To get the just-right interactions between protons and neutrons so that stable atoms, molecules, and chemistry are possible, it is critical that the strong nuclear force be exquisitely fine-tuned in several different ways.
Protons carry a positive charge, which, under the influence of the electromagnetic force, causes them to strongly repel one another. It takes the much more powerful attractive effect of the strong nuclear force to overcome the repulsive force of electromagnetism so that two or more protons will reside together in the nucleus of the atom. However, both the range over which the strong nuclear force is attractive and the strength of the attraction must be carefully fine-tuned for life to be possible.
If the effect of the strong nuclear force operated over even a slightly longer range by just a few percent, the universe would produce too many heavy elements for physical life to be possible. If it were slightly shorter range in its effect, again by just a few percent, too few heavy elements would form for physical life to be possible. If the strong nuclear force were just 4 percent stronger, the diproton (an atom with two protons and no neutrons) would form, which would cause stars to so rapidly exhaust their nuclear fuel as to make any kind of physical life impossible. On the other hand, if the strong nuclear force were just 10 percent weaker, carbon, oxygen, and nitrogen would be unstable and again life would be impossible.1
For life to be possible it is critical that the strong nuclear force be attractive only over lengths no greater than 2.0 fermis and no less than 0.7 fermis (one fermi = a quadrillionth of a meter) and maximally attractive at about 0.9 fermis.2 At lengths shorter than 0.7 fermis, it is essential that the strong nuclear force be strongly repulsive. The reason why is that protons and neutrons are packages of more fundamental particles called quarks and gluons. Each proton is a package made up of two up quarks and one down quark plus the relevant gluons, while each neutron contains two down quarks and one up quark with their relevant gluons. If the strong nuclear force were not strongly repulsive on length scales below 0.7 fermis, the proton and neutron packages of quarks and gluons would merge. Such mergers would mean no atoms, no molecules, and no chemistry would ever be possible anywhere or any time in the universe. As with the attractive effect of the strong nuclear force, the repulsive effect must be exquisitely fine-tuned in both its length range of operation and the strength level of the repulsion.
The strong nuclear force is both the strongest attractive force in nature and the strongest repulsive force in nature. The fact that it is attractive on one length scale and repulsive on a different length scale makes it highly unusual and counterintuitive. Nevertheless, without these weird properties life would be impossible.
Several years ago, particle physicists performed a number of experiments that verified the strong nuclear force indeed manifests all the exceptionally exquisite fine-tuning described above. Theoreticians proposed that the long-range (0.7 to 2.0 fermis) part of the strong nuclear force could be attributed to the exchange of the lightest of the strongly interacting particles, the pi-mesons or pions, while the short-range (less than 0.7 fermis) part could be attributed to the exchange of heavier mesons. However, explaining the extremely repulsive nature of the short-range strong nuclear force required a large number of different heavy mesons with an incredibly varied range of internal structure. The situation was so complex that many particle physicists gave up any hope of ever achieving a complete theoretical analysis and calculation of the relevant phenomena.
A breakthrough came when a team of Japanese physicists and computer scientists developed a set of sophisticated algorithms that they ran continuously for several months on the world’s biggest and fastest parallel computers. Never before had so much computing power been focused on a single problem. Though the team was not able to produce a complete solution to the problem of the operation of the repulsive part of the strong nuclear force, they were able to verify all the fine-tuning design observed by the experimentalists and that the repulsive effect indeed results from the exchange of certain heavy mesons.3 In other words, the exchange of mesons phenomenon, otherwise known as quantum chromodynamics, now has both experimental and theoretical comfirmation.
As exhilarating as the confirmation of the amazing fine-tuning design in the strong nuclear force may be for believers in the biblical creation model, there is more. Further numerical calculations of quantumchromodynamics phenomena should reveal to particle physicists exactly how the strong nuclear force becomes amended as (1) the masses for each of the individual quark types are slightly altered, (2) various environmental conditions for the quarks are changed, and (3) a number of different parameters pertaining to both the repulsive and attractive effects of the strong nuclear force are modified. That is, as the world’s most powerful supercomputers are trained on the remaining quantumchromodynamics problems, particle physicists and the rest of the human race can look forward to discovering even more evidence for the supernatural designs that allow complex nuclear chemistry to occur and, thus, permit the existence of physical life.