Recently Leonard Susskind introduced a new type of objects and called them ziggs.
Ziggs are supposed to form a condensate. Massive particles emit and absorb the ziggs, by exchanging them with the condensate.
The HBM a uses a mechanism in which charge carriers are exchanged between the quantum state function of a particle with a second quaternionic probability amplitude distribution (QPAD) that is coupled to the quantum state function. The second QPAD is formed by the superposition of the tails of the quantum state functions of distant particles. In this sense the second QPAD fulfills the role of the ziggs condensate.
QPAD’s are continuous quaternionic distributions that contain a scalar field in their real part and a vector field in their imaginary part. Ordinary field theory can be applied in order to study the behavior of these fields. In a QPAD the scalar field can be interpreted as corresponding to a charge density distribution. Similarly the vector field can be interpreted as a corresponding current density distribution. The charge carriers can be interpreted as tiny patches of the parameter space of the distributions. All quantum state functions share the affine versions of their parameter spaces. In the HBM this space is called Palestra. It comprises the whole universe. The coupling of QPAD’s affects the density of the charge carriers in the neighborhood of the corresponding particle. Since these carriers are patches of the parameter space the local curvature of the parameter space is affected. On the other hand the coupling attaches the quantum state function to the tails of quantum state functions of remote particles. This establishes inertia.
With other words if the carriers are the ziggs, then the ziggs establish gravitation as well as inertia.
The HBM is treated in a ten page paper: http://www.scitech.nl/English/Science/EssentialsOfTheHilbertBookModel.pdf.