What is
Antimatter? - Page 3
There is no intrinsic difference between particles
and antiparticles; they appear on essentially the same footing
in all particle theories. This means that the laws of physics
for antiparticles are almost identical to those for particles;
any difference is a tiny effect. But there certainly is a
dramatic difference in the numbers of these objects we find
in the world around us; all the world is made of matter. Any
antimatter we produce in the laboratory soon disappears because
it meets up with matching matter particles and annihilates.
Modern theories of particle physics and of the
evolution of the universe suggest, or even require, that antimatter
and matter were equally common in the earliest stages--so
why is antimatter so uncommon today? The observed imbalance
between matter and antimatter is a puzzle yet to be explained.
Without it, the universe today would certainly be a much less
interesting place, because there would be essentially no matter
left around; annihilations would have converted everything
into electromagnetic radiation by now. So clearly this imbalance
is a key property of the world we know. Attempts to explain
it are an active area of research today.
In order to answer this question, we need to better
understand that tiny part of the laws of physics that differ
for matter and antimatter; without such a difference, there
would be no way for an imbalance to occur. This distinction
is the subject of study in a number of experiments around
the world that focus on differences in the decays of particles
called B-mesons
and their antiparticle partners. These experiments will be
done both at electron-positron collider facilities called
B
factories and at high-energy
hadron colliders, because each type of facility offers
different capabilities to contribute to the study of this
detail of the laws of physics--a detail that is responsible
for such an important property of the universe as the fact
that there is anything there at all!
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