Anti-Matter
Ordinary matter has negatively charged
electrons circling a positively charged
nuclei. Anti-matter however 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. (Encarta 99) The Research
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. (Encarta 99) 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) they are attempting 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 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 (along with 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 at once. (Encarta 99) So how can
anti-matter
be stored? Outer 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, it does not work for anti-neutrons, for example.
The Unanswerable
Question Though anti-matter can be slowly manufactured,
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 the made of anti-matter that
somehow became separated from matter
long ago. A problem with the 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 anti-matter anywhere. 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 there 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 is
produced 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. (Encarta
99)
The Chemistry 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.
(Galactic Positron Annihilation) The two
heavy particles meet in a flare of
energy and vanish. Their mass is converted to
high-energy radiation while
their opposite charges and baryon numbers cancel
out. We can make antiprotons
in the laboratory by turning this process round,
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 Still two. 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.
(Galactic
Positron Annihilation) The Article The article I read about on
the Internet,
reflects on recent advancements in anti-matter research.
Scientists in
Switzerland have begun experimenting with a LEAR device
which would slow the
particle velocity by a billionth of its original
velocity. This is all done in
an effort to slow the velocity to such a speed
where it can combine chemically
with positrons to form anti-hydrogen.
(Galactic Positron Annihilation) The
author of the article, whose name was
not included on the article, failed to
investigate any other anti-matter
research laboratories and their advancements.
The author focused on the
CERN research laboratory in Geneva.(Encarta 99) The
article also focused on
the conniving into the discovering the anti-matter
secret, but did not
mention much on the destruction and mayhem anti-matter would
cause if not
treated with the utmost care and safety. Discovering anti-matter
could mean
the end of the Earth as we know it. One mistake could mean the
release of
high-energy gamma rays that could wipe out the life on earth in
mere
minutes.(Encarta 99) It was a quite interesting article, with a lot
of
information that could affect all of humanity. The article, however, did
not
address on the advantages or disadvantages of anti-matter nor did it
mention the
practical uses of anti-matter. They are too expensive to use for
powering rocket
ships, and are not safe for household or industrial use,
therefore having no
meaning to the general public. It is simply a race to see
who can make the first
anti-matter element. (Galactic Positron Annihilation)
Conclusion As research
continues into the field of anti-matter there might be
some very interesting and
practical uses of anti-matter in the future of
society. Until there is a
practical use, this is barely an attempt to prove
which research lab will be the
first to manufacture the anti-matter
elements.
Bibliography
Encarta 1999, Articles on Matter and
Anti-Matter Galactic Positron
Annihilation,
http://www.astro.nwu.edu/astro/purcell/511kev/mcgraw.html