When a planetary or other body is moving through the Dirac sea, then, along its surface (or the outer fringe of its atmosphaere, it the case of such being praesent), the motion of the Dirac sea is altered to that of the planet. [This would differ from the older idea of the "aether" as being a substance which could pass through a planet without altering its motion.] The surface of that planet is, where the abrupt change of motion must occur, must, due to this disruption, be lacking in (or have praesent less densely), the Dirac sea : in effect, a macroscopic sphaeric hole in the Dirac sea.

The photon can be regarded as a hole (more specifically a vortex, which is hollow like a whirlpool) in the Dirac sea;

the spin-zero pion can be considered as a hole (empty space) within a (box-like) proton (in contrast with a neutron, whose hole is filled by an electron which was pressed into it by gravitational force in a neutron-star).

While the photon is in motion, the centrifugal force of its vortex would appear as negative mass (i.e., as negative inertia), accounting for bending of light toward, instead of away from, the source of a gravitational field. [The normal behavior of a vortex is to be deflected by any force; any attraction of a vortex might have to be accounted for by a negative mass.] The negativity of a photon’s travelling-mass would be a natural relative effect – its being less dense than the density of medium through which it is travelling (i.e., the Dirac sea).

In order to function as binding-forces in a nucleus, pions must have negative mass (having a negative recoil and a negative impact) – this would be simply a natural result of their being holes, analogous with the electron-holes in the conduction-band.

The nucleus of a helium atom is 3 nucleons in a line, with the single neutron remaining positioned between the 2 protons.

While the pion-hole is travelling from a proton to the neutron, the electron contained within the neutron is travelling toward the other proton (to convert it temporarily into a neutron), whereas the hole in that other proton is travelling to the opposite end of the nucleus to become a hole in the proton there. Thus, there is more total movement of holes (3 times as much, in this case) as of the (boxed) electron. [It is this triplicity that would give rise to the notion of a 3-quark nucleon. Quarks cannot exist because a vibrating string would have no way of accommodating (incorporating) an electron into itself.]

the muon

The pion would appear to contain a 2-layered filled hollow space within itself; when the innermost contents escape at the time of its escape from the nucleus, it is known as a muon.

When the intermediary layer is also lost, the muon’s mass is diminished and it is reverted into being an electron, which is hollow with both inner layers absent.

This is why it is so resilient (like unto a hollow rubber ball) as to be constantly bouncing between the outer limit of its subshell in the atom, toward the nucleus and back.

In the cases of photons and pions the negativity of mass is merely relative (to the density of the Dirac sea); but an absolute negativity of mass may be found in gravitons. Because gravitational force is propagated above the velocity of light, the graviton must (according to relativity-theory) be of imaginary mass, which on being squared (in interactions) would be of negative mass. This negativity would, in like manner as with pions, be expressed as negative recoil and negative impact.

The soul is able to contain (compraehend) the physical universe (as according to the Yoga-acara); this would involve being 4-dimensional (in order to contain all of the 3-dimensional). Because (like gravitation) the mind is supraluminal, it is as such imaginary in each dimension; and because the 4^th power of an imaginary is positive, it would appear to be, when measured (as, in weighing the body of a person immediately before and immediately after death, where it is found that there is an abrupt loss at the moment of death), positive in mass.

In the Jaina cosmology, the mass of physical substances is assumed to the due to aggregation of souls.