  We consider four subsets of the complexified spacetime algebra, namely the
real even part, the real odd part, the imaginary even part and the imaginary
odd part. This naturally leads to the four connected components of the Lorentz
group, supplemented each time by an additional symmetry. We then examine how
these four parts impact the Dirac equation and show that four types of matter
arise with positive and negative masses as well as positive and negative
charges.

General Physics