Paul Dirac devised a relativistic wave equation - an equation that did not only
apply to particles with a velocity considerably less than c,
the velocity of light. The particles described therefore
obeyed the relativistic formula for their energy:

E^{2} = p^{2}c^{2} +
m_{0}^{2}c^{4}

Here energy is squared so its value could be either positive or
negative. E.g. if x^{2} = 4, then x = 2 or x = -2.

Because of his extreme "rationalism" he
insisted there must therefore exist particles with negative
energy.

Such particles would have outlandish
properties. By E = mc^{2} a particle with negative
energy would have negative mass. If, for instance, two
particles, one of positive mass the other negative, were each
given a static electrical charge one would pursue the other with
ever increasing velocity. Nothing of the sort has ever been
observed.

To get round this problem Dirac argued that
all negative energy levels were full up (Sporus does not
understand why this stipulation is necessary). Further,
**everything** was made of energy - somethingness, such as
matter, was made of positive energy and nothingness, such as
empty space, was made of negative energy. Hence if you zap some
emptyness with sufficient (+ve) energy some of the nothingness
is promoted up into positive energy and some somethingness
blinks into existence. (This is how new particles appear in
Cern type machines.)

This predicted anti-matter. Zap some
emptiness with +ve energy and some somethingness appears, some
matter. It moves off leaving a hole in the emptiness. This hole
is anti-matter. When the matter comes back and meets the hole
it falls in, releasing the original zapping energy. You get
total anihilation. (The anti-matter has positive mass - it is
an absence of negative mass; two negatives make a positive so it
is positively massive.)