Subject: What relation do negative energy particles have to gravity?

Dirac suggested that 'a vacuum consists of a sea of electrons in 
negative energy levels' (ref. Quantum Physics - Eisberg and 
Resnick - p47) and that if a photon with E=2MeC^2 interacts with 
such an electron then it can be exited to a +ve energy state 
producing an electron antielectron pair.
    But do all of these negative energy particles have any 
relation to gravity, which can also be considered as a negative 
energy? My reasons are that:
1. At the precise moment that a particle (say electron) is 
removed from the 'sea' of negative energy electron, 2 particles 
(with mass) are produced, and so the total amount of gravity in 
the universe changes by a tiny amount.
2. The change in gravity is at precisely the same point in space 
that the -ve energy electron was removed from.
3. Gamma rays usually only form electron-antielectron pairs when 
they hit a solid (say metal) target. Does this suggest that there 
are more -ve energy particles where you find dense matter (the 
same place that you find gravity). Does this suggest that -ve 
energy particles are not found in a uniform 'sea', but are either 
a mirror of +ve energy particles, or are strongly atracted to 
mass.

Re: What relation do negative energy particles have to gravity?