Two or 4 Forces of Nature ?

It is usually believed that there exists four forces like the four musketeers:

gravitation, electromagnetic, strong, weak.

The first two forces, gravitation and electrostatic are known since  two centuries. The electric force is in 1/r²  and 1/r for the potential. Similarly, The magnetic force in 1/r⁴ and its potential in 1/r³.

The strong and weak forces remain hypothetical: their fundamental laws are ignored.

The strong force, varies, depending of the taste of the scientist, from 10, 137 to 1000 times stronger than the electromagnetic interaction, depending on the author. The coupling constant of the electromagnetic interaction is assumed to be 1/137, the strong force is assumed to be 1 (why? nobody knows) although it is not a constant.

The weak force, recently unified with electromagnetism under the name electroweak interaction, could be entirely and only electromagnetic…

The fundamental laws of the strong and weak forces remain unknown. It is not the LHC with its Higgs boson, a modern philosophical stone or Holy Graal, that will solve the problem. As it is not by swatting a fly that its internal structure may be known, the high energies are unsuitable to explore the atomic nucleus.

The fundamental constants of the strong force are still inexistent in tables like the Handbook of Chemistry and Physics. Mainstream physics still ignores the physical nature of the nuclear interaction. It is therefore unable to explain why the nuclear energy is one million larger than the chemical energy and also predict that the nuclear energy is around one percent of the Einstein mass energy mc².

The nuclear interaction is electromagnetic

Bohr solved the problem of the atom two years only after Rutherford discovered the atomic nucleus. The nuclear shell model was imagined by analogy with the Bohr model of the hydrogen atom where the electrons orbite around the nucleus. One century later, a coherent theory of the nucleus is still inexistent : nuclear physics seems to be in a dead end. 

The reason of this long unsuccessful research by thousands of distinguished scientists comes from the belief that the nucleus behaves like the atom. The nucleus contains no predominant central particle, no nucleus around which  the nucleons may orbit. Therefore the angular momentum is undefined. With an orbital movement, the deuteron is comparable to binary stars whose stability is questionable.

Structure of the simplest bound nucleus, the deuteron:

For the sake of simplicity, let us consider the simplest compound nucleus, the deuteron, made of one proton and one neutron.

The proton contains the same electric charge as the electron, but of opposite sign. The not so neutral neutron  contains electric charges with no net charge. The intrinsic spin of the nucleons generates the proton and neutron magnetic moments by the rotation of their internal electric charges. The Pauli exclusion principle does not apply because the proton and the neutron are distinguishable. The spins of the proton and the neutron are known to be parallel in the deuteron. The electric charges and the magnetic moments may be assumed to be collinear by reason of axial symmetry. Indeed, the magnetic moment of the deuteron is close to the difference between the proton and neutron magnetic moments as was shown by Rabi. The magnetic moments of the proton and the neutron in the deuteron, being collinear and opposite, the  magnetic interaction between the magnetic moments of the deuteron nucleons is thus repulsive. The deuteron bindind energy can thus be calculated electromagnetically, as shown in my paper:

Electromagnetic Theory of the Binding Energy of the Hydrogen Isotopes - Springer

Bieler of the Rutherford laboratory imagined in 1924 a magnetic attraction equilibrating an electrostatic repulsion between the protons. Since the discovery of the neutron and the magnetic moments of the nucleons proving that the neutron contains electric charges, nobody, as far as I know, has tried to apply electromagnetism to the nuclear interaction.