All material that we see, taste and touch is made
up of tiny particles called atoms. The atom is the smallest
portion of an element, such as lead, oxygen, or carbon, that
is still considered to be that element. In the center of the
atom is a nucleus composed of two types of particles called
protons and neutrons. Surrounding the nucleus
is a cloud of swarming particles called electrons. Protons
have a positive electrical charge, electrons a negative charge
and neutrons, as the name suggests, are neutral in charge.
Suppose, though, that the protons of an atom
were negatively charged and the electrons positively charged?
What would we have then? The answer is antimatter. Material,
like we see all around us, but with a reversed charge.
The problem is that it isn't all around us. While
scientists have produced tiny amounts of antimatter in laboratories,
it doesn't seem to exist in large quantities anywhere in the
universe. When matter and antimatter come into contact they
"annihilate" each other and turn into a burst of energy
(gamma rays to be exact). Because of this, it is easy for scientists
to tell that no significant mass of antimatter exists in our
solar system. If the sun were made of antimatter, the solar
wind (particles shot off from the sun) would generate gamma
rays when they hit the Earth. The same is true for all the planets.
If Mars were made of antimatter the gamma rays from annihilation
as the solar wind hit would be easily detectable.
Mission Specialist Franklin Chang-Diaz works with the
Alpha Magnetic Spectrometer carried by the shuttle in
Using the same logic, scientists can infer that
no significant amount of antimatter exists in our galaxy, or
our local cluster of galaxies or even our supercluster of galaxies.
(A supercluster of galaxies is a group of galaxies about 100
million light years wide.) Yet, it should be there. When matter
is created from energy, as scientists believe happened in the
very early universe, antimatter is also created. A proton cannot
be created without also getting an oppositely-charged antiproton.
The same is true for electrons (the antimatter version of an
electron is called a positron).
The universe is a big place, and perhaps there
is a chance that the antimatter exists somewhere out beyond
our local galactic supercluster (perhaps there are whole galaxies
and galactic superclusters made of nothing but antimatter) but
there are no good theories about how it could get so far separated
from the matter. Some scientists and NASA tried to resolve this
riddle by using an experiment aboard a space shuttle in 1998
to try and detect the cosmic rays (atoms and parts of atoms
traveling through space) that may have originated in an antimatter
portion of the universe. No significant amount of these were
found. The few sources of antimatter that were detected seemed
to come from the core of energetic galaxies or quasars (which
are probably black holes that generate small amounts of antimatter
as they suck regular matter into themselves). None of the sources
detected was antimatter left over from the creation of the universe.
How can this be possible given that when matter
is created, so an equal portion of antimatter should also be
created? Some experiments have suggested that antimatter may
behave slightly differently than matter. In the very hot and
energetic early universe where energy was coalescing into matter
and antimatter and then annihilating back into energy, a tiny
portion of the antimatter may have decayed before it could annihilate
with matter. The tiny portion of matter (perhaps as few as 1
particle out of 100 million) left over would account for the
entire universe we now see - planets, moon, stars, and galaxies.
new AMS is scheduled to be placed aboard the International
Space Station sometime in 2002 or 2003 (NASA).
Still, some scientists think that there might
be large sections of universe made from antimatter. To try and
settle this matter, NASA will use the new Alpha Magnetic Spectrometer
(AMS) scheduled to be installed on the International Space Station
in 2002 or 2003. This AMS is designed to look for relatively
heavy antimatter -- anti-helium nuclei or particles even more
massive, such as anti-carbon, that may come zipping through
our solar system from far away antimatter galaxies.
Finding massive antimatter particles would be
important because normal high-energy particle interactions involving
regular matter don't usually produce heavyweight antimatter
such as anti-helium or anti-carbon. Such heavy antimatter would
most likely have been left over from the creation of the universe,
suggesting that somewhere out there is a mass of antimatter
that has so far gone undetected.
Copyright Lee Krystek
2001. All Rights Reserved.