Big questions, few answers
The nucleus consists of protons and neutrons. The more difficult question is explaining how these are bonded together. How are the protons held together in the nucleus? Why don’t protons in a nucleus repel each other? Since protons all have positive change, they should REPEL each other with the electrostatic force. The atomic nucleus should fly apart, according to classical electrostatic theory. Yet it does not.
Also, the neutrons have neutral charge, so what holds them in place? For that matter, what are the neutrons even doing in the nucleus? Why does the nucleus not consist only of protons?
There are a number of conventional theories in this area: liquid drop, shell models, and the strong force.
Liquid drop and semi-empirical mass formula
The liquid drop model assumes that the protons and neutrons (i.e. nucleons) are all thrown together without any specific internal structure or bonding arrangements. Think marbles in a bag like this image. It is called the ‘liquid drop’ because it assumes surface tension and bulk effects. Its usual manifestation is the semi-empirical mass formula (SEMF), which is a ‘model’ because it fits coefficients to a type of power series. It represents the general trends in binding energy. On the positive side, it offer an underlying theoretical justification for the various terms. However there are also several criticisms of the SEMF. It is dependent on a very generous power series with no less than seven tuneable parameters: with that number of variables it is not surprising that a fit can be obtained. Unfortunately the fit is poor: It doesn’t model the light nuclides well, it totally fails to represent the extinction of the heaviest nuclides, it doesn’t model the isotope limits (drip lines) well, and it doesn’t accommodate the fact that the nucleons come in whole units. Other criticisms are that the real nuclides show abrupt changes, that the SEMF does not represent.
There are also shell models. These are more abstract, being mathematical representations of combinations of protons and neutrons. However the shell models don’t really provide much insight into how the nucleons are bonded. The theory assumes that independent clusters (shells) of protons and neutrons exist. It is based on the mathematical idea of a harmonic oscillator in three coordinates, but it is difficult to give a physical interpretation of this. The theory predicts certain combinations of nucleons are especially stable, hence “magic numbers”. This model also predicts stability for large atoms (hence “island of stability”) beyond the current range of synthesised elements, though the predictions vary with the particular method used. The shell model has good fit for atomic numbers below about 50, but becomes unwieldy for high atomic numbers. The related interacting boson model which assumes that nucleons exist in pairs. However this limits the model to nuclides where p=n, which is an overly simplistic assumption.
Strong Nuclear force
From the perspective of the Standard Model of quantum theory, the protons in the neutron do experience electrostatic repulsion, but the STRONG NUCLEAR FORCE is even stronger and holds the protons together. That force is proposed to be a residual of the strong force that acts at the quark level. Quantum chromodynamics (QCD) proposes that the quarks inside the protons are bonded by the exchange of gluon particles, in the strong force. These gluons are massless particles and three types are proposed, called colours (red, blue, green). Hence the force is also called the colour force. At the quark level this force is proposed to haves some unusual characteristics:
(1) The strong force is strongly ATTRACTIVE at intermediate range, such that it overcomes the electrostatic force.
(2) At short range the strong force is presumed to be REPULSIVE. This attribute is needed to explain why the force does not contract the nucleus into a singularity.
(3) At long range the strong force is CONSTANT, and unlike the electro-magneto-gravitational (EMG) forces, does not decrease with distance. This is called colour confinement.
The colour force is consistent with known empirical data from the jets of material expelled at particle impacts. QCD is a good theory to explain what happens in high-energy particle impacts. But gluons have not been actually observed, only inferred from impacts, so other explanations are still possible.
Ideally the strong nuclear force would say how the protons and neutrons are bonded together, but there is a conceptual chasm in this area. It is unclear how the residual nuclear force (at nucleus level) emerges from the strong force (at quark level), except as a general concept that the gluons leak out. The theoretical details are lacking. Nor is it clear what structure it might impose on how the nucleons are arranged within the nucleus. It is also thought that the residual strong force causes BINDING ENERGY but again the exact mechanism is unknown. QCD is unable to predict even the most basic of nuclear attributes. It does not describe how multiple nucleons interact. It cannot explain the simplest nuclei, the hydrogen isotopes. It does not explain nuclear structure or the table of nuclides.
It is clear from observation that no nucleus exists with multiple protons and no neutrons, so evidently neutrons provide an important role within the nucleus, which is not represented in any of the existing theories.
Logically there should be a conceptual continuity between whatever force binds the protons and neutrons together, to an explanation of the properties of the nuclides. However QCD is stuck at the first stage, and the drop/shell models are marooned at the last stage.
Explaining why any one nuclide is stable, unstable (radioactive) or non-existent is not possible with any of these theories. Nor can existing theories explain why the nuclide series start and end where they do. They also do not explain why disproportionally more neutrons are needed as the number of protons increases (the stability line for p:n is curved as opposed to being a straight line).
If we take any one line of isotopes in the table of nuclides, such as Argon, then there are a number of questions.
Figure 1: Argon isotopes and key questions. Background image adapted from  https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html.
Answers in the Cordus mechanics – a design methodology
The Cordus physics answers many of these questions about the structure of the atomic nucleus. It is the only theory that can explain why any one nuclide is stable/unstable/non-existent, at least from H to Ne. The theory is based on COVERT STRUCTURES. This means that it predicts that particles are not actually zero-dimensional points, which is the standard premise of the conventional theories. Instead, the theory shows that solutions to these deep questions are possible providing one is willing to accept a design where particles have internal structures. Not just any covert structures either –the Cordus theory goes on to work out, using principles of engineering design, exactly what those structures would need to be. The theory predicts a specific string-like structure, and shows that if particles were to have this structure then many problems in fundamental physics can be given physically realistic explanations. The structure only becomes apparent at finer scales than the relatively coarse level at which quantum mechanics views the world.
What is the covert structure?
The theory predicts that a particle consists of two reactive ends, a small distance apart and joined by a fibril. These reactive ends emit discrete forces into the external environment. This whole structure is called a PARTICULE to differentiate it from a 0-D point particle. The particules react with other particules, e.g. bonding and forces, only at the reactive ends.
Figure 2: Proposed internal and external (discrete force) structures of the proton.
So, what does the Cordus theory say about nuclear structure?
The theory predicts that protons and neutrons are rod-like structures that interact at their two ends. So they have physical size. They join up in chains and networks, to form nuclear polymers. They preferentially bond proton-to-neutron, but will also bond proton-proton or neutron-neutron if there is no other choice. The theory explains how these bonds work, which is by the interlocking of the discrete fields of two or more nucleons. The atomic nucleus is thus proposed to consist of a polymer of protons and neutrons.
Figure 3: The synchronous interaction (strong force) bonds protons and neutrons together in a variety of way, resulting in nuclear polymer structures. These are proposed as the structure of the nucleus.
Some simple geometrically plausible assumptions may be added, in which case the design is able to explain a wide range of nuclides. For example it is necessary to assume that the polymer is generally be a closed loop (exceptions for the lightest nuclides) and there can be bridges across the loop. The polymer is required to take a specific shape, which is to wrap around the edges of a set of interconnected cubes. The cube idea might seem a bit strange, but is merely a consequence of having discrete three-dimensional fields for the proton and neutron. This need not be contentious as QCD has three colour charges.
The results show that the stability of nuclides can be qualitatively predicted by morphology of the nuclear polymer and the phase (cis/transphasic nature, or spin) of the particules. The theory successfully explains the qualitative stability characteristics of the nuclides, at least from hydrogen to neon and apparently higher.
This provides a radical new perspective on nuclear mechanics. This is the first theory to explain what holds the protons and neutrons in the nucleus, what the neutrons do in the nucleus, and why each nuclide is stable or unstable. It also explains why only certain nuclides exist, as opposed to being non-existent. It is also the first to do all this from first principles. Now it is still possible that all this good news is down to a luck chance, that the whole thing is spurious causality. If that were the case, then we would expect to see the theory collapse as it was applied to higher nuclides, or we would expect to see logical inconsistencies creep in as the theory was extended to other areas. So far there are none of those problems, but more work is necessary and until then we admit that this is still an open question. Nonetheless that it has been possible to achieve this, when no other theory has been able to come close to answering these questions, is promising.
The implications for fundamental physics are potentially far-reaching. Serious consideration must now be given to the likelihood that at the deeper level, particules have internal structure after all. This theory does not conflict with quantum mechanics but rather subsumes it: QM becomes a stochastic approximation to a deeper determinism, and the Standard Model of particle physics is re-interpreted as a set of zero-dimensional point-approximations to a finer-scaled covert structure. Now that would be something to be excited about.
Answers, according to the Cordus theory
Q: What is the atomic nucleus made of?
A: The nucleus consists of protons and neutrons that are rod-like structures (as opposed to 0-D points) that link into chains. These chains form a Nuclear polymer that is generally a closed loop (exceptions for the lightest nuclides) and there can be bridges across the loop. The polymer is required to take a specific shape, which is to wrap around the edges of a set of interconnected cubes.
Q: How are the protons held together in the nucleus?
A: An interlocking (synchronous) interaction. Forget the strong force – it turns out that’s not a helpful way to conceptualise the situation. What seems to be really happening is that the synchronous interaction holds both protons and neutrons together. It works by the synchronisation between discrete force emissions from neighbouring particules. One reactive end from each particule is thus locked together. The other reactive ends are free to make bonds with other particules. This explains why the effect is so ‘strong’ – it is an interlock. It also explains why the nucleus does not collapse in on itself (equivalent to ‘repulsive’ strong force). Furthermore these discrete forces continue out into the external environment (equivalent to ‘constant’ strong force at long-range). Furthermore, the Cordus theory predicts that the electrostatic force does not operate in the nucleus as it only applies to discoherent matter. Likewise the synchronous interaction only applies to coherent matter.
The theory gives an explanation of the nucleus, based in physical realism. This is a radical and highly novel outcome. If true, a conceptual revolution will be required at the fundamental level. Maybe its time … Physics is overdue for an earthquake.
12 Sept 2014
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