Antimatter? - Page 2
Dirac's prediction applies not only to the electron
but to all the fundamental constituents of matter (particles).
Each type of particle must have a corresponding antiparticle
type. The mass of any antiparticle is identical to that of
the particle. All the rest of its properties are also closely
related, but with the signs of all charges reversed. For example,
a proton has a positive electric charge, but an antiproton
has a negative electric charge. The existence of antimatter
partners for all matter particles is now a well-verified phenomenon,
with both partners for hundreds of such pairings observed.
New discoveries lead to new language. In coining the term
"antimatter," physicists in fact redefined the meaning
of the word "matter." Until that time, "matter"
meant anything with substance; even today school textbooks
give this definition: "matter takes up space and has
mass." By adding the concept of antimatter as distinct
from matter, physicists narrowed the definition of matter
to apply to only certain kinds of particles, including, however,
all those found in everyday experience.
Any pair of matching particle and antiparticle can be produced
anytime there is sufficient energy available to provide the
necessary mass-energy. Similarly, any time a particle meets
its matching antiparticle, the two can annihilate one another--that
is, they both disappear, leaving their energy transformed
into some other form.
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