Ordinary matter has negatively charged electrons circling a
positively charged nuclei. Anti-matter has positively
charged electrons - positrons - orbiting a nuclei with a
negative charge - anti-protons. Only anti-protons and
positrons are able to be produced at this time, but
scientists in Switzerland have begun a series of
experiments which they believe will lead to the creation of
the first anti-matter element: Anti-Hydrogen.
Early scientists often made two mistakes about anti-matter.
Some thought it had a negative mass, and would thus feel
gravity as a push rather than a pull. If this were so, the
antiproton's negative mass/energy would cancel the proton's
when they met and nothing would remain; in reality, two
extremely high-energy gamma photons are produced. Today's
theories of the universe say that there is no such thing as
a negative mass.
The second and more subtle mistake is the idea that
anti-water would only annihilate with ordinary water, and
could safety be kept in (say) an iron container. This is
not so: it is the subatomic particles that react so
destructively, and their arrangement makes no difference.
Scientists at CERN in Geneva are working on a device called
the LEAR (low energy anti-proton ring) in an attempt to
slow the velocity of the anti-protons to a billionth of
their normal speeds. The slowing of the anti-protons and
positrons, which normally travel at a velocity of that near
the speed of light, is necessary so that they have a chance
of meeting and combining into anti-hydrogen.
The problems with research in the field of anti-matter is
that when the anti-matter elements touch matter elements
they annihilate each other. The total combined mass of both
elements are released in a spectacular blast of energy.
Electrons and positrons come together and vanish into
high-energy gamma rays (plus a certain number of harmless
neutrinos, which pass through whole planets without
effect). Hitting ordinary matter, 1 kg of anti-matter
explodes with the force of up to 43 million tons of TNT -
as though several thousand Hiroshima bombs were detonated
Storage of Anti-matter
Space seems the only place, both for storage and for
large-scale production. On Earth, gravity will sooner or
later pull any anti-matter into disastrous contact with
matter. Anti-matter has the opposite effect of gravity on
it, the anti-matter is 'pushed away' by the gravitational
force due to its opposite nature to that of matter. A way
around the gravity problem appears at CERN, where fast
moving anti-protons can be held in a 'storage ring' around
which they constantly move - and kept away from the walls
of the vacuum chamber - by magnetic fields. However, this
only works for charged particles, not for anti-neutrons.
The Unanswerable Question
Though anti-matter can be manufactured, slowly, natural
anti-matter has never been found. In theory, we should
expect equal amounts of matter and anti-matter to be formed
at the beginning of the universe - perhaps some far off
galaxies are made of anti-matter that somehow became
separated from matter long ago. A problem with that theory
is that cosmic rays that reach Earth from far-off parts are
often made up of protons or even nuclei, never of
anti-protons or antinuclei. There may be no natural
In that case, what happened to it? The most obvious answer
is that, as predicted by theory, all the matter and
anti-matter underwent mutual annihilation in the first
seconds of creation; but why then do we still have matter?
It seems unlikely that more matter than anti-matter should
be formed. In this scenario, the matter would have to
exceed the anti-matter by one part in 1000 million.
An alternative theory expressed by the physicist M.
Goldhaber in 1956, is that the universe divided into two
parts after its formation - the universe that we live in,
and an alternate universe of anti-matter that cannot be
observed by us.
Though they have no charge, anti-neutrons differ from
neutrons in having opposite 'spin' and 'baryon number'. All
heavy particles, like protons or neutrons, are called
baryons. A firm rule is that the total baryon number cannot
change, though this apparently fails inside black holes. A
neutron (baryon number +1) can become a proton (baryon
number +1) and an electron (baryon number 0 since an
electron is not a baryon but a light particle). The total
electric charge stays at zero and the total baryon number
at +1. But a proton cannot simply be annihilated.
A proton and anti-proton (baryon number -1) can join
together in an annihilation of both. The two heavy
particles meet in a flare of energy and vanish, their mass
converted to high-energy radiation wile their opposite
charges and baryon numbers cancel out. Antiprotons can be
produced in the laboratory by turning this process around
and using a particle accelerator to smash protons together
at such enormous energies that the energy of collision is
more than twice the mass/energy of a proton. The resulting
reaction is written:
p + p p + p + p + p
Two protons (p) become three protons plus an antiproton
(p); the total baryon number before is:
1 + 1 = 2
And after the collision it is:
1 + 1 + 1 - 1 = 2
Anti-matter elements have the same properties as matter
properties. For example, two atoms of anti-hydrogen and one
atom of anti-oxygen would become anti-water.
As research continues into the field of anti-matter there
might be some very interesting and practical uses of
anti-matter in the society of the future. Until there is a
practical use, this is merely an attempt to prove which
research lab will be the first to manufacture the