  This paper discusses fundamental physical interactions starting from two
preliminary assumptions. (a) Although mass of gravity and mass of inertia are
equivalent quantities in their measured values, they are qualitatively not
identical physical entities. We will take into consideration this difference in
our equations. Then it extends this "equivalence-is-not-identity" principle to
sources of further fundamental interaction fields, other than gravity. (b)
Physical interactions occur between these qualitatively different entities.
First it interprets these assumptions. Then, it sketches a picture of
fundamental physical fields influenced by the distinction between the two
qualitative forms of the individual field-charges and interaction between them.
It applies the results of a former publication (Darvas, Concepts of Physics,
2009, 3), which mathematically proved the existence of an invariance between
the two isotopic forms of field-charges. It introduces the notion of
isotopic-field-charge-spin, proven as a conserved quantity. This conservation
predicts the existence of a boson mediating between the two possible
isotopic-field-charge-spin states. After these preliminary foundations, it
formulates certain consequences in the author s view on the physical structure
of matter. Finally the paper discusses how these issues can allow an
alternative interpretation of physical experience.
