Landmark Events in Science
20th Century
1950s
1950 Pioneering research in plasma physics is published.
In "Cosmical Electrodynamics," the Swedish astrophysicist
Hannes Alfvén summarizes his early work in plasma physics, the study
of ionized gases, which bears on phenomena within Earth's magnetic field such
as the northern lights, on space science, and on later research in nuclear fusion.
1950 The first computerized weather prediction is made.
Using the newly invented ENIAC computer, the Hungarian-born
American mathematician and computer pioneer John von Neumann and colleagues
make the first computerized 24-hour weather predictions.
1950 The National Science Foundation (NSF) is created.
In 1945 Vannevar Bush, an American mathematician, engineer, and wartime science
czar, had pointed out the crucial role of research in his report "Science --
The Endless Frontier." Five years later Congress passes the NSF Act for funding
basic research and science education.
1951 The first commercial electronic computer is built.
The American engineers John Mauchly & John Eckert
construct UNIVAC I, with 5,000 vacuum tubes and data storage on magnetic tape.
In 1952 a UNIVAC computer compiles polling results that anticipate the result
of the election of U.S. President Dwight Eisenhower.
1951 - 1952 A characteristic radio signal is observed
from interstellar hydrogen,
The American physicists Harold Ewen (left) & Edward
Mills Purcell observe a radio signal of 21-centimeter wavelength from hydrogen
atoms in space, providing a way to trace this basic building material of the
universe.
1951 Shockley patented junction transistor
1952 The electro-chemical properties of nerve impulses
are analyzed.
After work in the 1930s on the electrical properties
of the giant neurons found in squids, the English physiologists and biophysicists
Alan Lloyd Hodgkin & Andrew Fielding Huxley trace the chemical processes
responsible for the transmission of electrical impulses along nerve fibers.
1952 An initial X-ray analysis is made of DNA.
The British physical chemist Rosalind Franklin makes
X-ray studies of DNA, the complex organic molecule that encodes genetic information.
These will be used in establishing its structure.
1952 The first hydrogen bomb is exploded.
The United States tests an explosive fusion device
at Eniwetok Atoll in the Pacific Ocean. A fission bomb initiates thermonuclear
fusion of hydrogen, the process that makes the sun glow, in a 50-ton device.
H-bombs soon become small enough to carry in airplanes and missiles.
1952 - 1953 The forerunner of the laser is conceived
and built.
The American physicist Charles H. Townes, and Soviet
physicists Alexander Mikhailovich Prokhorov & Nikolai Gennadiyevich Basov,
independently suggest a way of inducing molecules to emit intense, coherent
microwaves. Townes (above) goes on to build and name the first maser (Microwave
Amplification by Stimulated Emission of Radiation).
1953 The double helix structure is proposed for DNA.
The British biologists Maurice Wilkins & Francis
Crick, together with the American biologist James Watson, discover the double
helical structure of the complex organic molecule that encodes genetic
information.
1953 The structure of a DNA molecule was discovered to
have the shape of a double helix by James Watson and Francis Crick.
1954 James Gordon, H.J. Zeiger and Charles Townes invented
the first operational maser, a microwave counterpart of the laser.
1954 The solar cell is invented.
Scientists at the Bell Telephone Company develop the
photovoltaic cell, a silicon device that uses sunlight to generate an electrical
current.
1954 - 1956 Fiber optics is born.
The discovery by the Dutch physicist Abraham van Heel
that a coating of film improves the transmission of light by glass fibers leads
to rapid development of the technique. In 1956 the Indian engineer Narinder
Kapany coins the phrase "fiber optics."
1956 The first commercial nuclear power plant opens.
Calder Hall, the first nuclear power station used (partly)
for peaceful purposes, opens in England.
1956 The radioimmunoassay procedure is invented.
The American nuclear physicist Rosalyn Sussman Yalow
develops a technique using radioactive tracer elements to measure minute concentrations
of biological and pharmaceutical substances. It is first used to study insulin
in the blood of diabetics.
1956 - 1957 A fundamental law of elementary particles
is overturned.
The law of conservation of parity specifies that elementary
particles and their mirror images would behave identically. After two Chinese-born
American physicists Tsung-Dao Lee & Chen Ning Yang (above, left to right)
propose that some subatomic processes violate this law, a team led by a third
Chinese-born American physicist, Chien-Shiung Wu, confirms the prediction.
1957 Superconductivity is explained.
The American team of John Bardeen, Leon Cooper, and
Robert Schrieffer resolves the old puzzle of superconductivity, discovered in
1911. They show that electrons in superconductors form pairs whose quantum properties
allow them to travel without losing energ
1957 The first orbiting spacecraft is launched.
In a stunning feat that ushers in the Space Age, the
Soviet Union launches the first artificial Earth satellite, the 184-pound Sputnik
I, followed by the 1,000 pound Sputnik II.
1958 Discovery of the Magnetosphere begins the era
of space physics.
The American scientist James van Allen includes Geiger
counters on the first U.S. space satellite and discovers a stable trapped radiation
belt containing protons. The discovery launches the new era of exploration of
the magnetospheres of the Earth and other planets.
1958 The integrated circuit is invented.
Robert Noyce, of Fairchild Semiconductor Corporation,
and Jack Kilby, of Texas Instruments, independently invent the integrated circuit,
which incorporates many transistors and other electronic com-ponents into one
chip made of the semiconductor silicon.(Above, Kilby's first integrated circuit.)
1958 Ultrasound is first used to examine unborn children.
Inspired by the success of anti-submarine sonar during
World War II, the British obstetrician Ian Donald begins to use high-frequency
soundwaves to examine fetuses in pregnant women. This ultrasound technique avoids
the risk of X rays, and becomes widely used in obstetrics and other medical
applications.
1958 - 1962 Quantum tunneling is explored and applied.
In 1958, the Japanese physicist Leo Esaki, working
at the Sony Corporation, uses quantum tunneling, which allows wave-like electrons
to penetrate barriers that are impassable according to classical physics --
in the tunnel diode, a new electronic device. In 1962 the 22-year old Cambridge
University student Brian Josephson finds that pairs of electrons can tunnel
between two separated superconductors, an effect that is used in sensitive magnetic
probes for geology, medicine and physics.
1959 A new quantum effect is predicted and confirmed.
The American physicist David Bohm, and his Israeli
graduate student Yakir Aharonov, predict that a magnetic field affects the quantum
properties of an electron in a way that is forbidden by classical physics. The
Aharonov-Bohm effect is observed in 1960 and hints at the wealth of surprises
still lurking in quantum mechanics.
1959 A new technique was invented in which a transistor
can be manufactured by constructing layers of semiconducting materials. This
type of transistor is called a planar transistor. This technology opened the
way for a mass production of transistors from flat silicon wafers.
1959 - 1962 The first artificial objects reach other celestial
bodies.
In 1959 the Soviet space probe Luna 2 crashlands on
the Moon and Luna 3 photographs its far side, never seen from Earth. In 1962
the U.S. probe Mariner 2 is launched on its voyage to Venus. (Left, color composite
photo of the Moon, 1990.)
1960s
1960 The year in which the first laser was successfully
tested. The first laser was a solid laser using a ruby rod, giving off a beam
of red laser light, the same kind you see at a grocery checkout counter.
1960 The first laser is built.
At the Hughes Aircraft company, the American physicist
Theodore Maiman extracts bright, highly focused light of a very pure color from
a ruby cylinder. The laser is a product of quantum theory, and is soon used
in a wide range of commercial applications.
1961 A truly landmark year. A complete self-functioning
electronic circuit consisting of
scores of parts was manufactured as a single piece out
of a silicon wafer. This is the integrated circuit , the chip, which was to
usher in the age of information. The credit for its invention is shared, independently
by Jack Kilby and Robert Noyes. The IC gets abbreviated to a single letter I
when combined with other words, such as in an LSI, a large scale integrated
circuit, or a VLSI, a very large integrated circuit.
1961 The basic code of life was cracked, connecting the
sequences of base molecules on a
DNA molecule to those of amino acids on a protein molecule.
1962 Semiconducter lasers are invented.
Researchers at GE, IBM, and the MIT Lincoln Laboratory
find that diode devices based on the semiconductor gallium arsenide convert
electrical energy into light. By the 1990s, billions of them are made yearly
for use in telecommunications and CD players.
1963 Chaos is identified in a dynamic system.
The American meteorologist Edward Lorenz notices that
small changes in parameters entered into a simple computer model of the atmosphere
strongly affect the predicted atmospheric behavior, in seemingly random ways.
This is deterministic chaos, which Lorenz calls the "butterfly effect": even
the minute flapping of a butterfly's wings can, in time, have large meteorological
consequences.
1963 Chaos is identified in a dynamic system.
The American meteorologist Edward Lorenz notices that
small changes in parameters entered into a simple computer model of the atmosphere
strongly affect the predicted atmospheric behavior, in seemingly random ways.
This is deterministic chaos, which Lorenz calls the "butterfly effect": even
the minute flapping of a butterfly's wings can, in time, have large meteorological
consequences.
1963 Quasars are discovered.
The Dutch-American astronomer Maarten Schmidt analyzes
the red shifted light emitted by astronomical object 3C 273 and shows it to
be extremely distant. This is the first known quasar, an object that looks star-like
but is brighter than some galaxies. Quasars may be associated with giant black
holes
1964 Quarks are proposed.
The American theorists Murray Gell-Mann & George
Zweig independently postulate the existence of quarks, particles with electric
charges that are fractions of those of electrons, as the building blocks of
protons and neutrons and other strongly interacting particles. This introduces
new order into the subatomic world. (Left, artist's fantasy of quarks in a silicon
nucleus.)
1965 Moore's Law is stated.
Gordon Moore, co-founder of the Intel Corporation,
notes that the number of active elements that can be placed on a computer chip
is doubling every 18 months. The rule known as Moore's Law continues to be closely
followed for over three decades. By the turn of this century, some chips will
contain up to 109 transistors.
1967 The fundamental forces begin to be unified.
The American physicists Steven Weinberg (right) &
Sheldon Glashow (left), and Pakistani physicist Abdus Salam (center) independently
create the electroweak theory, which unites the apparently different electromagnetic
and weak nuclear forces into a single "electroweak" force. A key prediction
of this theory is confirmed in 1983 with the discovery of the heavy W and Z
bosons, carriers of the weak force, by the Italian physicist Carlo Rubbia and
his research team. (Above, three laureates are about to receive the 1979 Nobel
prize.)
1967 The theory of plate tectonics is developed.
The British geophysicists Dan McKenzie & Robert
Parker, and the American geophysicist W. Jason Morgan independently describe
Earth's crust as divided into enormous moving plates. The theory explains mountains,
volcanoes, and earthquakes, and is consistent with continental drift, which
Alfred Wegener introduced in 1915.
1967 The solar neutrinos pose a problem.
The thermonuclear fusion that powers the Sun produces
neutrinos, elementary particles with little or no mass. The American chemist
Raymond Davis builds the first solar neutrino detector deep in the Homestake
Gold Mine and detects fewer neutrinos than predicted. Other measurements confirm
the discrepancy.
1967 The home microwave oven is introduced.
The Raytheon Corporation adapts WW II radar technology
to develop the first successful microwave oven for home use -- the Amana Radarange.
1967 - 1968 Pulsars are discovered, and interpreted as
neutron stars.
In England, graduate student Jocelyn Bell & her
adviser Anthony Hewish discover periodic radio pulses from certain stars. The
American astrophysicist Thomas Gold proposes that these pulsars are rotating
neutron stars, the dense remnants of supernova explosions.
1969 The first direct evidence for quarks is found.
Experiments by American physicists Jerome I. Friedman,
Henry Kendall, Richard E. Taylor and others, yield the first evidence that the
quarks proposed in 1964 actually exist inside protons and neutrons. The technique
is similar in principle to Rutherford's 1911 discovery of the atomic nucleus.
1969 Humans land on the Moon.
In an achievement that begins the direct human exploration
of astronomical bodies, U.S. astronaut Neil Armstrong becomes the first human
being to walk on the Moon. Here he is reflected in Buzz Aldrin's visor.
1970s
1970 Silicon chips become available as computer memories.
The Intel corporation realizes $9 million in sales
the first year it introduces a computer memory chip that can store 1024 bits
of information.
1970 - 1971 Several large telescopes begin operations.
With funding from the U.S. National Science Foundation,
new optical telescopes enter service at sites with excellent viewing: 157-inch
instruments at Kitt Peak, Arizona, (left) and Cerro Tololo, Chile, and an 88-inch
unit atop Mauna Kea Volcano, Hawaii. In addition, a radio telescope 300 feet
across begins observing near Bonn, Germany. In 1992, Mauna Kea adds a 393-inch
multi-mirror telescope.
1970 - 1973 The standard model of elementary particles
is developed.
The "standard model" explains three of the four fundamental
forces (electromagnetic, weak and strong nuclear forces, omitting only gravity).
They link indivisible particles classified as leptons, such as electrons and
muons, quarks, and force carriers, such as photons, gluons and heavy bosons.
1970 - 1974 The vulnerability of the ozone layer is demonstrated.
The atmospheric ozone layer absorbs most of the sun's
ultraviolet light that would otherwise harm life on Earth. Three chemists --
the Dutch-born German Paul Crutzen, the American F. Sherwood Rowland, and the
Mexican-born American Mario Molina -- explore natural and artificially induced
processes that destroy ozone. Their work contributes to the 1987 international
Montreal Protocol, which phases out the production of certain refrigerants and
other products harmful to the ozone layer.
1971 The first microprocessor, a complete computer on
a single chip, became a reality. The chip known as the Intel 4004 chip, contained
about 2000 components. A four-megabit chip of today contains, on a chip about
the size of a baby’s fingernail, roughly 8 million parts.
1971 - 1980 A possible Theory of Everything is proposed.
The English physicist Michael Green and the American
physicist John Schwarz extend "string" theory -- which treats elementary particles
as vibrations of minute strings rather than as points in space -- into "superstring"
theory. It incorporates a novel relationship called supersymmetry that places
particles and force carriers on an equal footing. By 1997, superstring theory
seems capable of uniting quantum mechanics with the theory of relativity to
explain all known particles and forces including gravity, but remains experimentally
untested.
1971 - 1980 Magnetic resonance imaging (MRI) is introduced
for medical diagnosis.
In1939,theAmerican physicist Isidor Isaac Rabi showed
how to study atoms and molecules through their magnetic properties. In 1946,
two other Americans, Edward M. Purcell and the Swiss-born Felix Bloch, separately
apply this nuclear magnetic resonance (NMR) method to solids and liquids. In
1971, researchers begin adapting NMR into magnetic resonance imaging, a non-invasive
method to examine internal bodily structures, which becomes commercially available
in 1980.
1972 A new superfluid form of helium is found.
Working at a sample temperature barely above absolute
zero, the American physicists Douglas Osheroff, Robert Richardson, & David
Lee show that the isotope helium-3 becomes a superfluid, a liquid that flows
without internal friction. Superconductivity (discovered in 1911), superfluidity
(1938) and laser action (1952) are examples of quantum behavior directly observable
on the human scale.
1972 The speed of light was measured to an unprecedented
accuracy using a laser beam
produced by a helium-neon gas mixture. For those who
cherish accuracy to the very last digit, the speed of light was measured to
be 299,792,4562 +/- 0.0011 km/s.
1972 The first Computerized Tomography (CT) scan is
made.
The British engineer Godfrey Hounsfield, using methods
developed by the South African-born American physicist Allan Cormack, combines
X-ray images to display the interior of the human body in three dimensions.
The CT scan becomes a prime tool for diagnosing brain and spinal disorders.
1972 The first earth resources technology satellite is
launched.
NASA launches LANDSAT I, the first of a series of satellites
that use a variety of cameras and sensors (including infrared detectors) to
examine the earth's mineral and agricultural resources, as well as its oceans
and atmosphere. (Left, LANDSAT image of an Italian coastline, 1975.)
1973 The discovery of the first superconducting material,
a niobium compound, to display its property above the boiling point of liquid
hydrogen.
1974 A mechanism is proposed for black holes to emit energy.
The English physicist Stephen Hawking, who occupies
the Cambridge University professorship once held by Isaac Newton, suggests that
despite their overwhelming gravity, black holes can cause emission of subatomic
particles from the space around them, and eventually evaporate as their energy
is transferred away.
The English physicist Stephen Hawking, who occupies
the Cambridge University professorship once held by Isaac Newton, suggests that
despite their overwhelming gravity, black holes can cause emission of subatomic
particles from the space around them, and eventually evaporate as their energy
is transferred away.
1974 The renormalization group technique is developed.
The American physicist Kenneth Wilson develops a mathematical
method to describe certain phase changes, such as the spontaneous rearrangement
of atoms that occurs at a critical temperature in some crystals. He shows how
to account for fluctuations in the system over widely different scales of length.
1976 Spacecraft search for biological activity on Mars.
U. S. spacecraft Viking I and II land on Mars and examine
its surface. Tests for microorganisms in the soil first seem to give positive
results, but further analysis shows that they reveal non-living chemical processes.
1975 Solid state devices detect astronomical light.
Charge-coupled devices (CCDs), detectors of light based
on semiconductors, are first attached to telescopes and used to observe the
planet Uranus. They are more sensitive than photographic film, and greatly extend
the power to see into the universe.
1975 - 1977 Fractals are introduced.
At IBM, the Polish-born American mathematician Benoit
B. Mandelbrot presents his concept of fractals, complex geometric objects whose
component parts seen from up close resemble the entire structure from far away.
These help to classify and analyze order in natural phenomena, such as the branching
of blood vessels, rivers, and trees, the turbulence in fluids, and the distribution
of galaxies in space.
1977 The Apple II computer is introduced.
The American inventors Steven Jobs & Stephen Wozniak
produce the first personal computer sold in assembled rather than kit form.
It is unrivaled until the IBM PC is introduced in 1981.
1977 The Apple II personal computer, with all the memory
power of four kilobytes, appeared and set in motion what we now call the PC
revolution.
1978 The first genetically engineered drug was mass produced
human insulin.
1978 The existence of dark matter is confirmed.
Following Fritz Zwicky's pioneering work in 1933, the
American astronomer Vera Rubin and her coleagues analyze how galaxies rotate,
and conclude that the gravity due to their visible matter is insufficient to
hold them together; hence they must also contain invisible or dark matter.
1979 Theories of polymers and liquid crystals are developed.
The French physicist Pierre-Gilles de Gennes presents
his contributions to the theories of polymers and liquid crystals. With new
methods of manufacture, by the 1990s both types of material appear in a variety
of applications, including computer displays, automobile bodies, and electro-optic
devices.
1980s
1980 Applications of the laser technology went into a
full swing. Industrial applications
include cutting, welding, aligning and surveying. It plays a crucial role in
the field of precision
surgery, as well as in optoelectronic telecommunication, not to mention the
laser guidance
system for missiles and bombs.
1980 In this year the macrocomputer revolution began
in earnest, followed by the introduction of the IBM-PC in 81, IBM-PC XT (extended)
in 85, Apple Macintosh in 84, IBM-PC AT (advanced) technology) in 86, and IBM-PS/2
in 87
1980 The inflationary universe is proposed.
The Big Bang origin of the universe is generally accepted,
but fails to explain details of the distribution of the cosmic background radiation
and other observations. The American physicist Alan Guth draws on ideas of particle
physics to propose that the Big Bang was followed by a time of extremely rapid
growth. This suggestion inspires a proliferation of hypothetical histories of
the cosmos.
1980 A quantized electrical effect is discovered in
semiconductors.
In the nineteenth century, the American physicist Edwin
Herbert Hall found that a current-carrying material placed in a magnetic field
develops a voltage perpendicular to the current. In 1980, the German physicist
Klaus von Klitzing discovers that in a semiconductor held at low temperatures,
this Hall voltage varies in quantum-sized steps. The result is used in the development
of new, highly accurate electrical standards.
1981 The scanning tunneling microscope is invented.
The German physicist Gerd Binnig (right) and the Swiss physicist Heinrich Rohrer
(left) develop a microscope in which a specimen is scanned by measuring the
minute electrical current between the surface and an extremely fine metallic
tip. The technique can produce a computer-generated map of a surface showing
the outlines of individual atoms.
1981 The laser is used in surgery.
A laser removes tissue with minimal heating of its
surroundings. In 1961, only a year after its invention, a physicist and ophthalmologist
had used a ruby laser to destroy a tumor on the retina of a human eye. Later,
laser surgery is developed for corneal sculpting.
1981 Dedicated synchrotron light sources become operational.
In a synchrotron, electrons accelerated to high speeds
around a circular track emit intense beams of X-ray, ultraviolet, and infrared
light. These are useful in the analysis of solids, molecules, atoms, and biological
systems. They can also serve technological purposes such as etching computer
chips. In
1981, the first synchrotron designed for the production
of X rays rather than research in elementary particles begins operations at
Daresbury, England.
1982 Compact discs (CDs) are introduced.
The CD, a 5-inch diameter plastic disc that carries
information encoded as tiny pits read by a laser, is introduced together with
CD players. The first CD is Billy Joel's "52nd Street."
1982 Fractional electric charges are discovered.
At Bell Laboratories Chinese-born Daniel Tsui &
the German physicist Horst Störmer, investigating the "quantum Hall effect,"
discover that at extremely low temperatures electrons confined to move in a
plane and subjected to a strong perpendicular magnetic field can behave as though
they carried a fraction of an electric charge. This totally unexpected phenomenon
is explained by theoretician Robert Betts Laughlin in terms of quantized bundles,
or whirlpools, of magnetic field which replace electrons as current carriers,
and are associated with one third of an elementary electric charge each.
1985 A new form of carbon is found.
The American chemists Richard Smalley & Robert
Curl, & the British chemist Harold Kroto, find that 60 carbon atoms can
arrange themselves into molecules shaped like a soccer ball, or a geodesic dome
as designed by Buckminster Fuller. These buckyballs provide a flexible base
for the design and application of new materials. (Left, micrograph of a thin
film of carbon with a 70 atom buckyball.
1985 Tools for computational physics become more powerful.
The American computer designer Seymour Cray introduces
the CRAY-2, which performs 109 mathematical operations per second. By the 1990s,
such supercomputers are simulating highly complex physical phenomena, from the
distribution of galaxies in the universe and the behavior of terrestrial storms
(above) down to the molecular structure of water.
1986 The discovery of the first superconductor, a nonmetal,
that begins to superconduct at
temperatures above the boiling point of liquid helium.
1986 The first hepatitis vaccine produced by the DNA recombinant
technology.
1986 "High temperature" superconductors are found.
At the IBM Zurich Research Laboratory, the Swiss physicist
Karl Alexander Müller (left) & his German partner Johannes Georg Bednorz
(right) discover materials that become superconducting at temperatures far above
absolute zero. This increases the range of commercial uses of superconductivity.
1987 The discovery of the first material that superconducts
at above the boiling point of the
relatively inexpensive and readily available liquid nitrogen.
1988 The first patent ever given for a genetically
engineered living animal, a cancer-prone
mouse.
1987 Neutrinos and gamma rays are detected from a supernova.
The detection of neutrinos from the Supernova 1987A
in the Large Magellanic Cloud indicates stellar core collapse. The subsequent
detection of gamma rays confirms the synthesis of heavy elements in the explosion.
1989 The Great Wall of galaxies is found.
After surveying 5,000 galaxies, the American astronomers
Margaret Geller & John Huchra find that they are arranged in thin sheets
wrapped around huge voids nearly empty of galaxies, like a froth of soap bubbles.
Among these sheets, the Great Wall stretches millions of light years. It is
the largest known structure in the universe.
1989 The World-Wide Web is launched.
The Brisish engineer Tim Berners-Lee and colleagues
at the Swiss-based international elementary particle laboratory CERN create
Hypertext Transfer Protocol (HTTP), a standardized communication mode for computer
networks. Point-and-click software is introduced in 1993, and HTTP becomes the
dominant means of information transfer over the global Internet.
1989 - 1992 The cosmic background radiation is explored.
NASA launches the Cosmic Background Explorer (COBE)
satellite in 1989. It records maps of minute variations in thermal radiation,
represented by different colors, across the sky. Contributions from the Milky
Way, included in the upper background image, have been eliminated in the lower
image to reveal ripples in the thermal radiation left over from the Big Bang.
1990s
1990 The Hubble Space Telescope becomes operational.
The Hubble Telescope, built under the supervision of
the U.S. National Aeronautics and Space Administration (NASA), is placed into
orbit above the Earth's obscuring atmosphere. After an optical flaw is corrected,
Hubble examines the universe at high resolution in wave lengths from the ultra-violet
to the infrared.
1991 Astronomy and astrophysics begin to flourish at previously
unexplored wavelength.
Astronomers increasingly view the universe at all wavelengths,
using orbiting satellites such as the U.S. Gamma Ray Observatory and Extreme
Ultraviolet Explorer, the German ROSAT (ROentgen SATellite) and Japanese Yokhoh
for X rays; the ESA (European Space Agency) Infrared Space Observatory; and
very long baseline arrays, whose antennas are scattered across continents for
extremely high resolution radio astronomy.
1993 The Global Positioning System (GPS) is completed.
Culminating a 20-year project, the U.S. Air Force launches
the last of 24 Navstar satellites that carry atomic clocks. Users anywhere on
Earth can determine precise location from this network for navigation, auto-mobile
guidance, hiking, and geophysical research.
1993 A nuclear fusion reactor produces high power.
Working at temperatures higher than those inside the
Sun, the Tokamak reactor at Princeton University generates megawatts of power
for one second through thermo-nuclear fusion of hydrogen isotopes. Later the
device achieves even higher powers, and although it delivers less energy than
it uses, these are important steps toward obtaining power from fusion.
1994 Planning begins for a 21st century accelerator.
Construction of the world's most powerful particle
accelerator is approved at CERN, the Eurpean research consortium near Geneva,
Switzerland. To be built in an existing tunnel 17 miles around, it will accelerate
and collide high-energy protons to search for objects such as the proposed Higgs
particle which is thought to interact with all elementary particles, and to
endow them with mass.
1994 New physical techniques are proposed to sequence
DNA.
The Human Genome Project began in 1990 as a massive
15-year undertaking to analyze or sequence human DNA, which will give a complete
genetic map (genome). Rapid new physical sequencing methods are proposed in
1994, variously using lasers, photolithographic methods as developed for the
semiconductor industry, and detection of single molecules.
1994 Silicon technology begins to be used for micromachines
and optoelectric devices.
The techniques used to make intricate integrated circuits
from silicon are extended to construct minute mechanical systems, for uses such
as measuring blood pressure by the deformation of a tiny silicon diaphragm.
A porous form of silicon, which emits light under a voltage, is examined for
use in optoelectronic devices.
1995 The new state of matter is achieved for trapped
atoms.
In 1924-25, the Indian physicist Satyendra Nath Bose
& Albert Einstein predicted that extremely cold atoms would condense into
a single quantum state. In 1995, a team under the direction of the American
physicists Eric Cornell & Carl Wieman trap a cloud of 2,000 metallic atoms
cooled to less than a millionth of a degree above absolute zero, producing a
Bose-Einstein condensate. This accomplishment leads to the construction of an
atom laser in 1997, (Left to right, the approach to condensation: The spread
of temperatures in the cloud is represented by the width of the hill, which
shrinks as more atoms join the developing condensate).
1995 The structure of a protein fundamental for metabolism
is determined.
Cytochrome c oxidase is a complex protein central to
the metabolic processes that transfer energy within living cells. In 1995, two
research groups crystallize the material and determine its molecular structure
by X-ray analysis, enlarging the understanding of life processes.
1995 The rotation of Earth's inner core is detected.
Using measurements of earthquake waves,and computer
simulation, the American geophysicists Xiaodong Song & Paul Richards show
that Earth's solid inner core, 1,500 miles in diameter, rotates inside the liquid
outer core slightly faster than the rest of the planet.
1995 Jupiter and its moons are explored at close range.
The Galileo spacecraft, launched in 1989, reaches Jupiter.
It sends pictures and data back to Earth, and drops a probe into the Jovian
atmosphere to sample its composition.
1995 The top quark is found.
Researchers use the Tevatron machine at the Fermi National
Accelerator laboratory near Chicago to detect the sixth and last member of the
quark family of fundamental particles. Some earlier results from accelerators
around the world that led to the development of the standard model for the make-up
of matter include the discovery of the muon neutrino (1962), the charmed quark
(1974), the tau lepton (1975), and the bottom quark (1977)
1997 Quantum action at a distance is confirmed over a
range of kilometers.
Quantum theory predicts that two widely separated particles
can be "entangled" so a measurement on one instantaneously affects the measured
proper ties of the other. Einstein called this troubling effect "spooky," but
encouraged by earlier observations in various laboratories, a Swiss group, led
by physicist Nicolas Gisin, confirm it over a distance of eleven kilometers.
1997 The Pathfinder mission explores Mars.
A NASA spacecraft lands on Mars and delivers Sojourner,
a small wheeled vehicle that examines the surface and its rocks to probe the
past and present of Martian geology. (Above, a 360 panorama photo.)
1998 - 2008 The solar neutrino puzzle may be solved.
The Sudbury Neutrino Observatory (SNO) in Ontario is
designed to solve the solar neutrino problem that cropped up in 1967. Nuclear
physicists and astrophysicists have predicted the number of neutrinos produced
in solar fusion that should arrive on Earth -- but experimentalists detect only
about a third as many. The solution of the mystery may require that neutrinos
have mass, and avoid detection by changing character on their way to Earth.
The experiment illustrates the interdependence of the atomic and the cosmic
realms in a particularly compelling way.
1998 - 2008 Weather and climate predictions come of
age.
The size and complexity of the atmosphere make weather
prediction a physics problem of excruciating difficulty. By 1997 supercomputers,
satellite data collection, and progress in applied mathematics have brought
meteorology to the brink of maturity. With their aid, three-day forecasts have
become as reliable as one-day forecasts were 15 years ago. Eventually, however,
prediction will run into a fundamental limitation: the butterfly effect, discovered
in 1963, inevitably spoils detailed forecasts beyond about two weeks in advance.
Fortunately this problem will not prohibit long-range climate prediction.
2000 - 2010
1999 - 2009 Simulation of Brain Functions in Real Time.
Neural network simulations of brain functions such
as pattern perception, sensorimotor control, and memory, on high-capacity computer
chips, will allow robots to interact with their environments in real time --
another step toward understanding human intelligence.
2000 - 2010 Photonics competes with electronics.
In principle, photons can transmit, manipulate, and
store information more efficiently than electrons. Optical fibers are beginning
to replace the copper wires that have been used for data transmission for more
than a century. However, the all-optical computer, with photonic integrated
circuits, is still in its infancy. When it matures, revolutionary new ways to
make thinking machines will become possible.
2000 - 2010 Gravitational waves open a new window on
the universe.
Gravitational waves -- not yet detected by 1999 --
are believed to ripple through the spacetime of the universe. A new detection
system planned for Louisiana, Washington State, and other sites around the world,
is expected to find them. The Laser Interferometer Gravitational wave Observatory
(LIGO) will reveal cosmic phenomena unlike any ever recorded by optical or radio
telescopes, and provide stringent new tests of General Relativity and the Big
Bang theory.
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- Compiled by D. Brewer - April 2000