March
Important historic
dates in science
March
31: Sir
Lawrence Bragg
(Born March 31, 1890:
Died July 1, 1971)
Australian-born British physicist and X-ray crystallographer, who at the
early age of 25, shared the Nobel Prize for Physics in 1915 (with his
father, Sir William Bragg). Lawrence Bragg formulated the Bragg law of
X-ray diffraction, which is basic for the determination of crystal structure:
n[lambda] = 2dsin[theta] which relates the wavelength of x-rays [lambda],
the angle of incidence on a crystal [theta], and the spacing of crystal
planes d, for x-ray diffraction, where n is an integer (1, 2, 3, etc.).
Together, the Braggs worked out the crystal structures of a number of
substances. Early in this work, they showed that sodium chloride does
not have individual molecules in the solid, but is an array of sodium
and chloride ions.
March
30: Auguste
Bravais
(March 30, 1863: Born
August 23, 1863)
French physicist and mineralogist, best remembered for his work on the
lattice theory of crystals. Bravais lattices are named for him. In 1850,
he showed that crystals could be divided into 14 unit cells for which:
(a) the unit cell is the simplest repeating unit in the crystal; (b) opposite
faces of a unit cell are parallel; and (c) the edge of the unit cell connects
equivalent points. These unit cells fall into seven geometrical categories,
which differ in their relative edge lengths and internal angles. In 1866,
he elaborated the relationships between the ideal lattice and the material
crystal. Sixty years later, Bravais' work provided the mathematical and
conceptual basis for the determination of crystal structures after Laue's
discovery of X-ray diffraction in 1911.
March
29: Test
ban treaty
In 1960, British Prime
Minister Harold Macmillan reached agreement with U.S. leaders in Washington,
D.C., on a nuclear test ban treaty to be put to the U.S.S.R.
March
28: Nuclear
accident
In 1979, a nuclear
accident occured at the Three Mile Island nuclear power plant outside
Harrisburg, Pennsylvania, USA. Caused by human and mechanical errors,
a cooling system malfunctioned and permitted a partial meltdown of the
reactor's core. Some radioactivity leaked into the atmosphere. Although
it is the worst U.S. nuclear accident, disaster was avoided.
March
27: Wilhelm
Conrad Röntgen
(Born March 27, 1845:
Died February 10, 1923)
German physicist who was a recipient of the first Nobel Prize for Physics,
in 1901, for his discovery of X rays, which heralded the age of modern
physics and revolutionized diagnostic medicine.
March
26: Max
Abraham
(Born March 26, 1875:
Died November 16, 1922)
German physicist whose life work was almost all related to Maxwell's theory.
The text he wrote was the standard work on electrodynamics in Germany
for a long time. Throughout his life, he remained strongly opposed to
Einstein's Theory of Relativity, objecting to its postulates which he
felt were contrary to classical common sense. He further held that the
experimental evidence did not support that theory. In 1902, he had developed
a theory of the electron in which he held that an electron was a perfectly
rigid sphere with a charge distributed evenly over its surface. He also
believed in the ether theory, thought that future astronomical data would
validate it, and thus relativity was not in fact a good description of
the real world.
March
25: Radium
In 1903, The Times
newspaper reported that the French physicist, Pierre Curie assisted by
Mme Curie, communicated to the Academy of Sciences that the recently discovered
Radium "possesses the extraordinary property of continuously emitting
heat, without combustion, without chemical change of any kind, and without
any change to its molecular structure, which remains spectroscopically
identical after many months of continuous emission of heat ... such that
the pure Radium salt would melt more than its own weight of ice every
hour ... A small tube containing Radium, if kept in contact with the skin
for some hours ... produces an open sore, by destroying the epidermis
and the true skin beneath ... and cause the death of living things whose
nerve centres do not lie deep enough to be shielded from their influence.
March
24: Peter
Debye
(Born March 24, 1884:
Died November 2, 1966)
Petrus (Peter) Josephus Wilhelmus Debye was a Dutch physical chemist whose
investigations of dipole moments, X rays, and light scattering in gases
brought him the 1936 Nobel Prize for Chemistry. Most of his work was in
chemical-physics with special interest in electrolytes and dipolar momentum
analysis. He established a theory of specific heat with some improvements
on that proposed by Einstein. Debye performed important work in the analysis
of crystalline powders using X-ray diffraction techniques. He also determined
the dimensions of gaseous molecules and the interatomic distances using
X-rays.
March
23: Cold
fusion
In 1989, two Utah
scientists claimed they have produced fusion at room temperature. Martin
Fleischmann and Stan Pons announced in Utah how they had sustained a controlled
nuclear fusion reaction in a test-tube that generated up to 100 per cent
more energy than they put in. Then followed efforts to replicate the work.
Leading scientists failed. There were sporadic sightings of excess heat,
which Fleischmann said cannot be accounted for by chemistry alone. Crucially,
there were no tell-tale signs of nuclear processes, notably subatomic
particles called neutrons. Thus, the idea of cold fusion has been discredited.
March
22: Burton
Richter
(Born March 22, 1931)
American physicist who was jointly awarded the 1976 Nobel Prize for Physics
with Samuel C.C. Ting for the discovery of a new subatomic particle, the
J/psi particle.
March
21: Plutonium
named
In 1942, a secret
report was submitted suggesting the name "plutonium" for artificial
element 94 since it followed neptunium and uranium (elements 93 and 92).
The symbols Pu and Np were also suggestions. The paper was held secret
until after WW II, when it was published by the Journal of the American
Chemical Society in 1948. The authors were Glenn Seaborg and Arthur C.
Wahl. Since McMillan and Abelson had named neptunium after the planet
that lies outside of the orbit of Uranus, the name for the next element
in the periodic table was named after the next planet, Pluto. But instead
of "plutium," the authors decided on the name "plutonium."
Seaborg said, " It just sounded better." They also liked "Pu"
instead of "Pl."
March
20: Polykarp
Kusch
(Born January 26,
1911: Died March 20, 1993)
German-American physicist who, with Willis E. Lamb, Jr., was awarded the
Nobel Prize for Physics in 1955 for his accurate determination that the
magnetic moment of the electron is greater than its theoretical value,
a vital determination that led to revised theories about the interactions
of electrons with electromagnetic radiation.
March
19: Frédéric
Joliot-Curie
(Born March 19, 1900:
Died August 14, 1958)
French physical chemist, husband of Irène Joliot-Curie, who were
jointly awarded the 1935 Nobel Prize for Chemistry for their discovery
of artificially prepared, radioactive isotopes of new elements. They were
the son-in-law and daughter of Nobel Prize winners Pierre and Marie Curie.
March
18: First
spacewalk
In 1965, Voskhod 2
was launched into space carrying Aleksey Leonov and Pavel Belyayev aboard.
On the second orbit Leonov left the spacecraft through the air lock while
still tethered to the vessel. He was the first man to climb out of a spacecraft
in space. While outside, he took motion pictures and practiced moving
outside of the spacecraft for 10 minutes. Voskhod 2 made 17 orbits at
about 110 miles above earth.
March
17: Irène
Joliot-Curie
(Born September 12,
1897: Died March 17, 1956)
French physical chemist, wife of Frédéric Joliot-Curie,
who were jointly awarded the 1935 Nobel Prize for Chemistry for their
discovery of new radioactive isotopes prepared artificially. She was the
daughter of Nobel Prize winners Pierre and Marie Curie.
March
16: Yves-André
Rocard
(Born: May 22, 1903:
Died: March 16, 1992)
French mathematician and physicist who contributed to the development
of the French atomic bomb and to the understanding of such diverse fields
of research as semiconductors, seismology, and radio astronomy. During
WW II, as Head of the Research Department of the Free French Naval Forces
in England, he learnt about radars in England and interference from strong
radio emission from the Sun. After the war, Rocard returned to France
and proposed that France started a project to conduct radio astronomy.
In the last part of his life he studied biomagnetism and dowsing which
reduced his standing in the eyes of many of his colleagues.
March
15: Arthur
Holly Compton
(Born:
September 10, 1892: Died: March 15, 1962)
American physicist and engineer. He was a joint winner, with C.T.R. Wilson
of England, of the Nobel Prize for Physics (1927) for his discovery and
explanation of the change in the wavelength of X rays when they collide
with electrons in metals. This so-called Compton effect is caused by the
transfer of energy from a photon to a single electron, then a quantum
of radiation is re-emitted in a definite direction by the electron, which
in so doing must recoil in a direction forming an acute angle with that
of the incident radiation. During WW II, in 1941, he was appointed Chairman
of the National Academy of Sciences Committee to Evaluate Use of Atomic
Energy in War, assisting in the development of the atomic bomb. (Image:
Compton (left) with his assistant Richard L. Doan, 1936.)
March
14: Albert
Einstein
(Born March 14, 1879:
Died April 18, 1955)
German-American physicist who developed the special and general theories
of relativity and won the Nobel Prize for Physics in 1921 for his explanation
of the photoelectric effect. Recognized in his own time as one of the
most creative intellects in human history, in the first 15 years of the
20th century Einstein advanced a series of theories that proposed entirely
new ways of thinking about space, time, and gravitation. His theories
of relativity and gravitation were a profound advance over the old Newtonian
physics and revolutionized scientific and philosophic inquiry.
March
13: Sir
Federico Cesi
(Born March 13, 1585:
Died August 1, 1630)
Italian scientist who founded the Accademia dei Lincei (1603, Academy
of Linceans or Lynxes), often cited as the first modern scientific society,
and of which Galileo was the sixth member (1611). Cesi first announced
the word telescope for Galileo's instrument. At an early age, while being
privately educated, Cesi became interested in natural history and that
believed it should be studied directly, not philosophically. The name
of the Academy, which he founded at age 18, was taken from Lynceus of
Greek mythology, the animal Lynx with sharp sight. He devoted the rest
of his life to recording, illustrating and an early classification of
nature, especially botany. The Academy was dissolved when its funding
by Cesi ceased upon his sudden death.
March
12: Sir
William Henry Bragg
(Born July 2, 1862:
Died March 12, 1942)
Sir William Henry Bragg was a pioneer British scientist in solid-state
physics who was a joint winner (with his son Sir Lawrence Bragg) of the
Nobel Prize for Physics in 1915 for research on the determination of crystal
structures. During the WW I, Bragg was put in charge of research on the
detection and measurement of underwater sounds in connection with the
location of submarines. He also constructed an X-ray spectrometer for
measuring the wavelengths of X-rays. In the 1920s, while director of the
Royal Institution in London, he initiated X-ray diffraction studies of
organic molecules. Bragg was knighted in 1920.
March
11: Arthur
Jeffrey Dempster
(Born August 14, 1886:
Died March 11, 1950)
American physicist who built the first mass spectrometer, a device used
to separate and measure the quantities of different charged particles,
such as atomic nuclei or molecular fragments. He used a magnetic analyzer
that focused ions into an electrical collector. His mass spectrography
studies of uranium samples revealed the isotope uranium-235 (1935), the
primary fuel in atomic bombs and reactors.
March
10: Val
Logsdon Fitch
(Born March 10, 1923)
American particle physicist who was corecipient with James Watson Cronin
of the Nobel Prize for Physics in 1980 for an experiment conducted in
1964 that disproved the long-held theory that particle interaction should
be indifferent to the direction of time. Working with Leo James Rainwater,
Fitch had been the first to observe radiation from muonic atoms; i.e.,
from species in which a muon is orbiting a nucleus rather than an electron.
This work indicated that the sizes of atomic nuclei were smaller than
had been supposed. He went on to study kaons and in 1964 began his collaboration
with James Cronin, James Christenson, and René Turley which led
to the discovery of violations of fundamental symmetry principles in the
decay of neutral K-mesons.
March
9: Mesons
In 1948, the University
of California at Berkeley and the Atomic Energy Commission officially
announced the artificial production of mesons using the 184-inch cyclotron
at the university's Radiation Laboratory. Time reported the discovery
and hinted that the study of mesons might "lead in the direction
of a vastly better source of atomic energy than the fission of uranium."
March
8: Otto
Hahn
(Born March 8, 1879:
Died July 28, 1968)
German chemist who, with the radiochemist Fritz Strassmann, is credited
with the discovery of nuclear fission. He was awarded the Nobel Prize
for Chemistry in 1944 and shared the Enrico Fermi Award in 1966 with Strassmann
and Lise Meitner. Element 105 carries the name hahnium in recognition
of his work.
March
7: William
Draper Harkins
(Born December 28,
1873: Died March 7, 1951)
American nuclear chemist who was one of the first to investigate the structure
and fusion reactions of the nucleus. In 1920, Harkins predicted the existence
of the neutron, subsequently discovered by Chadwick's experiment. He made
pioneering studies of nuclear reactions with Wilson cloud chambers. In
the early 1930's, (with M. D.Kamen) he built a cyclotron. Harkins demonstrated
that in neutron bombardment reactions the first step in neutron capture
is the formation of an "excited nucleus" of measurable lifetime,
which subsequently splits into fragments. He also suggested that subatomic
energy might provide enough energy to power the Sun over its lifetime.
March
6: Bohr's
model of the atom
In 1913, this date
was written by Niels Bohr on his first paper describing his new ideas
on atomic structure, and mailed to his mentor, Ernest Rutherford. It was
one of three historic papers he wrote on this subject.
March
5: Coperian
theory decreed false
In
1616, Copernican theory is declared "false and erroneous" in
a decree written by Cardinal Robert Bellarmine, and issued by the Catholic
Church in Rome. Further, no person was to be permitted to hold or teach
the theory that the earth revolves around the sun. When Galileo subsequently
violated the decree, he was put on trial and held under house arrest for
the final eight years of his life.
March
4: Richard
C. Tolman
(Born March 4, 1881:
Died September 5, 1948)
Richard Chace Tolman was an American physicist and chemist who demonstrated
that electrons are the charge-carrying entities in the flow of electricity,
and also made a measurement of its mass. During the Manhattan Project
of WW II, he was the chief scientific adviser to Brig. General Leslie
Groves, the head of military affairs overseeing the development of the
atomic bomb. After the war he was adviser to the U.S. representative to
the United Nations Atomic Energy Commission.
March
3: William
Penney
(Born June 24, 1909:
Died March 3, 1991)
(Baron Penney of East Hendred) British nuclear physicist who led Britain's
development of the atomic bomb. Penney was to Britain as Oppenheimer was
to the U.S. He was a prominent part of the British Mission at Los Alamos
during WW II, where his principal assignment was studying the damage effects
from the blast wave of the atomic bomb, but he became involved in implosion
studies as well. Penney's combination of expertise, analytical skill,
effective communication, and the ability to translate them into practical
application soon made him one of the five members of the Los Alamos "brain
trust" that made key decisions. He was the only Briton to be part
of the ten man Target Committee that drew up the list of targets for the
atomic bombing of Japan.
March
2: Radioacitvity
reported
In 1896, Henri Becquerel
reported his discovery of the penetrating rays of a uranium compound to
the French Academy of Sciences. The photographic plate, fogged by these
rays, showing the outline of a metal cross lying between the compound
and the plate, is the first recognition of the effects later known as
radioactivity.
March
1: Radioactivity
discovered
In
1896, Henri Becquerel discovered radioactivity when he developed the photographic
plate he left in a desk drawer and found it had fogged with the image
of the uranium compound crystals resting on it. Thus, the discovery was
in fact the result of a chance occurrence. He had originally stored objects
together on February 26, after postponing his intended experiment on phosphorescent
emissions stimulated by the sun. Instead he now found spontaneous and
penetrating rays, independent of any input of energy. The mysterious nucleus
of the atom had been revealed, but realizing that took more years of research
by other scientists. He received a share of the 1903 Nobel Prize with
Pierre and Marie Curie for their work on radioactivity.
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