tions to within ten meters. (The military can aug-
ment the signals for greater accuracy.)
Chemistry and Physics Fundamental discoveries
include what may be the first of a new class of com-
pounds. In 1992, researchers in the United States
successfully combined helium and nitrogen at
77,000 times the Earth’s normal atmospheric pres-
sure to form a solid compound, a feat previously
thought impossible since helium is a noble gas and
should form no compounds.
Another fundamental discovery was made in
1995, this time by scientists at the Fermi National Ac-
celerator Laboratory in Batavia, Illinois. They pro-
duced top quarks by colliding protons and anti-
protons. Theory had long predicted the existence of
the top quark, but no evidence for it had been seen
before. Quarks are believed to be the fundamental
particles from which the familiar proton and neu-
tron are made. More specifically, theory predicts
six kinds of quarks that differ in electric charge
and other properties analogous to charge. These
other properties are whimsically named: up, down,
strange, charmed, top, and bottom. The proton is
thought to be made of two up quarks and one down
quark, while the neutron is made of an up quark and
two down quarks.
It has been known since 1938 that cooling
helium-4 below 2.17 Kelvin produced a liquid
superfluid. For example, since superfluid helium is
already in its lowest energy state, it cannot lose en-
ergy to friction, so it flows without friction. Unless
warmed above 2.17 Kelvin, superfluid helium will
flow effortlessly up the walls of its container and
down the outside walls until it has all escaped. This
special state of matter is known as a Bose-Einstein
condensation and is named for Satyendra Nath Bose
and Albert Einstein, whose theories predicted it. In
1995, Eric Cornell and Carl Wieman chilled rubid-
ium-87 vapor to 170 nanokelvin and showed that it
became a Bose-Einstein condensate just as theory
predicted. This was the first such condensate to be
made after helium-4. Such condensates are impor-
tant because they make quantum behavior visible on
a macroscopic scale.
Biology and Genetics The international Human
Genome Project officially began in 1990. Its purpose
was to map the estimated 100,000 genes on the
twenty-three pairs of human chromosomes in the
hope that this would lead to the diagnosis and cure
of genetic diseases. The DOE and the NIH were the
project’s initial backers. They were joined by other
nations and by corporations hoping to patent useful
genetic material and medications. The first draft of
the genome was published in 2001.
In July, 1997, a group of eleven scientists (includ-
ing five from the United States) announced that
a study of Neanderthal deoxyribonucleic acid
(DNA) was sufficiently different from that of mod-
ern humans that intermarriage can be ruled out.
Apparently, the Neanderthals were an evolutionary
dead end.
The following year, the American James A.
Thomson was able to isolate human embryonic stem
cells. This provoked controversy since his process in-
volved destroying human blastocysts (an early stage
in the development of an embryo). In another
breakthrough, biologist William French Anderson
developed a technique to insert a healthy gene to re-
place a damaged gene, a process known as gene ther-
apy. That raised the question of designer children:
Should parents be allowed to pick the eye color,
body type, and intelligence of their children?
The 1990’s brought the ever-increasing use of
DNA as evidence in criminal trials. An early case in-
volved DNA evidence from a rape victim. At the trial,
the prosecution claimed that there was only one
chance in 300 million that the DNA came from any-
one other than the accused, and the jury convicted
him. The defendant appealed in 1992, but in the
first major federal ruling on the use of DNA evi-
dence, the court of appeals upheld the lower court’s
decision to allow the evidence.The 1991 Gulf War The Gulf War was a proving
ground for military technology. For example, the
M-1A1 Abrams tank was touted as the world’s best
tank. It could travel up to 75 kilometers per hour (45
miles per hour) and fire accurately while bouncing
across the terrain. Its 105-millimeter (4.1-inch)
shells traveled 1,000 meters (3,280 feet) farther than
shells from Iraqi tanks. The tank’s shells were filled
with depleted uranium, 2.5 times denser than steel,
to give them greater penetrating power. (Depleted
uranium is only mildly radioactive and is dangerous
only as a fine powder since it can then be ingested.)
In one well-publicized incident, an Abrams gun was
tracking an Iraqi tank as it went behind a sand dune.
The Abrams’s shell went right through the sand
dune and still destroyed the tank.The Nineties in America Science and technology 755