Big bang and supernova analogies ...
‘Dr Edward Teller remarked recently that the origin of the earth was somewhat like the explosion of the atomic bomb…’
– Dr Harold C. Urey, The Planets: Their Origin and Development, Yale University Press, New Haven, 1952, p. ix.
‘It seems that similarities do exist between the processes of formation of single particles from nuclear explosions and formation of the solar system from the debris of a supernova explosion. We may be able to learn much more about the origin of the earth, by further investigating the process of radioactive fallout from the nuclear weapons tests.’
– Dr P.K. Kuroda, ‘Radioactive Fallout in Astronomical Settings: Plutonium-244 in the Early Environment of the Solar System,’ Radionuclides in the Environment (Dr Edward C. Freiling, Symposium Chairman), Advances in Chemistry Series No. 93, American Chemical Society, Washington, D.C., 1970.
The fractionation of fallout particles (which have a core of refractory material - i.e., high melting point material - surrounded by material with a lower melting point which has condensed at a later time in the fireball history), and their spherical nature, is similar in a way to planets. Obviously there are many differences.
One of the main ones is that a typical fallout particle, 1 millimetre in diameter or smaller, is drawn into a spherical shape by electrical attractive forces called surface tension - similar to the reason why water forms droplets. But planets are held together by gravity, not surface tension. The main difference is that surface tension acts on the outer surface area which in turn causes internal compression.
Gravity, however, is not due to a surface compression but instead is mediated through the void between fundamental particles in atoms by exchange radiation which does not recognise macroscopic surfaces, but only interacts with the subnuclear particles associated with the elementary units of mass. The radial contraction of the earth's radius by gravity, as predicted by general relativity, is 1.5 mm. [This contraction of distance hasn't been measured directly, but the corresponding contraction or rather 'dilation' of time has been accurately measured by atomic clocks which have been carried to various altitudes (where gravity is weaker) in aircraft. Spacetime tells us that where distance is contracted, so is time.]
This contraction is not caused by a material pressure carried through the atoms of the earth, but is instead due to the gravity-causing exchange radiation of gravity which is carried through the void (nearly 100% of atomic volume is void). Hence the contraction is independent of the chemical nature of the earth. (Similarly, the contraction of moving bodies is caused by the same exchange radiation effect, and so is independent of the material's composition.)
Since most of the mass of atoms is associated with the fields of gluons and virtual particles surrounding quarks, these are the gravity-affected parts of atoms, not the electrons or quarks themselves.
The mass of a nucleon is typically 938 MeV, compared to just 0.511 MeV for an electron and 5 MeV for a quark. Hence the actual charges of matter aren't associated with much of the mass of material. Almost all the mass comes from the massive mediators of the strong force fields between quarks in nucleons, and between nucleons in nuclei heavier than hydrogen. (In the well-tested and empirically validated Standard Model, charges like fermions don't have mass at all; the entire mass is provided by a vacuum 'Higgs field'. The exact nature of the such a field is not predicted, although some constraints on its range of properties are evident.)
Getting back to the topic at the top of this post, every type of force is nuclear in a broad sense. Gravity is basically nuclear because it depends on mass, which is concentrated in the exchange radiation between quarks in the nuclei of atoms. (If gravity was like electric charge, it would depend presumably on macroscopic surface area, which is not the case: in a charged metal sphere, the net electric charge involved in long range forces resides on the surface of the sphere not throughout its volume.) Electromagnetism in the form of the Yang Mills exchange-radiation U(1) symmetry has been unified with the weak nuclear force isospin symmetry SU(2) to produce the electroweak portion of the standard model, SU(2) x U(1), which has 4 gauge bosons that cause forces: the massive charged W+ and W- particles, the uncharged but massive Z particle, and the uncharged and light velocity (no 'rest mass') force causing photon.
The reason why only one (the photon) of the four electroweak gauge bosons operates outside nuclear distances is simply that the other gauge bosons are attenuated by the vacuum at low energy. At high energy collisions (ie, near the charge core, assuming the particles have are able to hit hard enough to break through the vacuum shield) there is attenuation and the weak nucelar force is experienced.
The quark is like a steel cored, rubber coated ball. Throw it gently (low energy) and all the interactions are soft, because the rubber shield is able to prevent the steel core from experiencing any direct interaction. But if you hit nuclear matter together very hard, the rubber is less effective at insulating the core and metallic interactions occur. It is really almost as simple as this; this is not a completely fraudulent analogy. Vacuum polarisation and shielding cause much of the 'rubber' type insulation. There is however some additional complexity which I've recently described on another blog, here, but as stated there it is not as complex as the supersymmetry formulation of the Standard Model.
The strong nuclear force is described in the Standard Model by colour rotation symmetry, SU(3). It has 8 massive gluon mediators, twice as many as the electroweak force. The observed effective colour charge of quarks falls off with increasing collision energy, while the observed electromagnetic force increases with collision energy. These facts suggest that energy may be conserved between all types of gauge boson; the fall of the coupling for the strong force is accompanied by an increase in the coupling for the electromagnetic force.
Conservation of energy of gauge bosons would suggest that when the polarised vacuum is completely broken down (at short ranges/high energies) and the electromagnetic force is maximised, the strong nuclear force will have fallen to the same value (not less than that value). Hence, including conservation of energy for the sum of gauge bosons of the fields automatically does what SUSY (supersymmetry) sets out to do, but instead of inventing unobserved imaginary superpartners like SUSY, we are utilising including a well-established physical principle (conservation of mass-energy) to do the same job.
Of the four usually distinguished elementary forces of the universe (the strong nuclear, weak nuclear, electromagnetic and gravitational), some 50% at first glance appear to be nuclear in origin (i.e., the strong and the weak forces). However, as we have shown, electromagnetism has been unified with electromagnetism - and this electroweak unification predicted the masses of the W+, W-, and Z massive weak gauge bosons discovered at CERN in 1983, so it is hard real science. Hence on this basis there are three fundamental force categories (electroweak, strong, and gravity) of which near 67% are nuclear (electroweak ad strong). When you include the fact that gravity depends essentially on the nuclear mass between quarks as discussed above, you then see that 100% of the fundamental forces of the universe are intimately nuclear in origin.
Back to the nuclear weapons and supernova analogy. Successive neutron captures in the explosion create very heavy elements like uranium which make the Earth radioactive today. See the previous post on this blog for the evidence for the 15 natural nuclear reactors in Gabon which occurred on Earth 1.7 billion years ago emitting 100 kW for 150 million years, when the ratio of U-235 to U-238 in uranium was higher than today (U-235 has the shorter half-life), and evidence of how nature contained the vast amount of intensely radioactive fission products for two billion years in perfect safety without any fancy concrete domes or expensive burial schemes!
More on the Oklo natural nuclear fission reactor in a comment on Louise Riofrio's blog here.