Nuke History

X-rays to H-bombs

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1895

WHAT:
X-rays
* Mysterious rays capable of penetrating solid bodies.

WHO:
Wilhelm Röentgen

HOW:
* Produced in Cathode Ray Tube and detected by Scintillation Screen or Photographic Plates.

NOTES:
* Accidental and unforeseen discovery prompts a flood of research.
* Named “X” after the mathematical term for an unknown.
* Immediately applied to medicine.
* Astonishing photos pique public interest.

In their own words:
* On a New Kind of Rays by Wilhelm Conrad Röntgen (1845-1923); source: read before the Würzburg Physical and Medical Society, 1895.

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Wilhelm Röentgen” “X-rays”
1896

WHAT:
Radioactivity
* Invisible rays discovered in Uranium acting similarly to X-rays.
* Penetrating rays capable of ionizing gases, but spontaneously emitted from Uranium, not mechanically generated.

WHO:
Henri Becquerel

HOW:
* Photographic Plates exposed to potassium uranyl sulfate.
* Looking for X-rays in flourescent minerals.

NOTES:
* Process cannot be altered by any known chemical or physical process.
* Indicates that atoms have an internal structure.
* Extremely minute amounts of material giving off appreciable amounts of energy indicates undreamed of quantities of energy within the atom.

In their own words:
* On Radioactivity, a New Property of Matter by Antoine Becquerel; source: Nobel Lecture, December 11, 1903
* On the rays emitted by phosphorescence. On the invisible rays emitted by phosphorescent bodies. by Antoine Henri Becquerel (1852-1908); source: read before the French Academy of Science 24 Feb. 1896
* On Hyperphosphorescence by Silvanus P. Thompson; source: Phil. Mag. 42, 103 (1896)[1]

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Henri Becquerel” “Radioactivity”

WHAT:
“Ionizing Radiation”
* X-rays and radioactivity cause ionization of gases.

WHO:
J.J. Thomson
Ernest Rutherford
* graduate student

HOW:
* Ions produced in gases exposed to X-rays or radioactivity.
* Early Cloud Chamber of C.T.R. Wilson placed in electromagnetic field.

NOTES:
* X-rays cause gases that are normally insulators to become conductors of electric current.
* First observation of ionizing radiation

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “J.J. Thomson” “Ernest Rutherford” ““Ionizing Radiation””
1897

WHAT:
Electron
* The fundamental unit of electricity.
* First elementary particle.

WHO:
J.J. Thomson

HOW:
* Applying electromagnetic fields to Cathode Rays causes rays to curve, enabling the measurement of the ratio between charge and mass.

NOTES:
* While atoms are uncharged on the whole, they contain negatively charged parts.

In their own words:
* Cathode Rays by J. J. Thomson; source: Philosophical Magazine, 44, 293 (1897)
* On the Masses of the Ions in Gases at Low Pressures. by J.J. Thomson, M.A., F.R.S.; source: Philosophical Magazine, December 1899, Series 5, Vol. 48, No. 295, p. 547-567
* On the Structure of the Atom: an Investigation of the Stability and Periods of Oscillation of a number of Corpuscles arranged at equal intervals around the Circumference of a Circle; with Application of the Results to the Theory of Atomic Structure by J.J. Thomson, F.R.S.; source: Philosophical Magazine, Series 6, Volume 7, Number 39, March 1904, p. 237-265
* On the Number of Corpuscles in an Atom by Prof J.J. Thomson, M.A., F.R.S.; source: Philosophical Magazine, vol. 11, June 1906, p. 769-781
* Carriers of Negative Electricity by J.J. Thomson; source: Nobel Lecture, December 11, 1906

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “J.J. Thomson” “Electron”
1898

WHAT:
Alpha Rays
Beta Rays
* Rays differentiated within radioactivity.

WHO:
Ernest Rutherford

HOW:
* Observing how radiation is absorbed by differing thicknesses of aluminum, distinguished a more intense radiation that is more easily absorbed, “Alpha”, and a less intense radiation but more penetrating, “Beta”.

NOTES:
* Beginning of Rutherford's many researches on the nature of radioactivity.

In their own words:
* Uranium Radiation and the Electrical Conduction Produced by It by E. Rutherford, M.A., B.SC.; source: Philosophical Magazine for January 1899, ser. 5, xlvii, pp. 109-163
* A Radioactive Substance emitted from Thorium Compounds by E. Rutherford, M.A., B.SC.; source: Philosophical Magazine for January 1900, ser. 5, xlix, pp. 1-14
* The Nature of the a Particle from Radioactive Substances by Ernest Rutherford (1871-1937) and T. Royds; source: Phil. Mag. 17, 281-6 (1909)
* The Chemical Nature of the Alpha Particles from Radioactive Substances by Ernest Rutherford; source: Nobel Lecture, December 11, 1908

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Ernest Rutherford” “Alpha Rays” “Beta Rays”

WHAT:
Polonium
Radium
* Naturally occurring elements discovered on the basis of their radioactivity.

WHO:
Marie Curie
* Called the first great woman scientist.
Pierre Curie

HOW:
* Isolated from pitchblende, a Uranium ore.
* Detection with Electrometer invented by Pierre Curie using piezoelectricity.

NOTES:
* Birth of Radiochemistry.
* Quantities of elements too small to be detected otherwise found by their intense radioactivity.

In their own words:
* Rays emitted by compounds of uranium and of thorium by Marie Sklodowska Curie (1867-1934); source: note presented by M. Lippmann, Comptes Rendus 126, 1101-3 (1898)
* On a New Radioactive Substance Contained in Pitchblende by M. P. Curie and Mme. S. Curie; source: note presented by M. Becquerel; Comptes Rendus 127, 175-8 (1898)
* On a new, strongly radioactive substance, contained in pitchblende by M. P. Curie, Mme. P. Curie, and M. G. Bémont; source: note presented by M. Becquerel; Comptes Rendus 127, 1215-7 (1898)
* Radium and the New Concepts in Chemistry by Marie Curie; source: Nobel Lecture, December 11, 1911
* Radioactive Substances, Especially Radium by Pierre Curie; source: Nobel Lecture, June 6, 1905
* Radium and Radioactivity by Marie Sklodowska Curie; source: Century Magazine (January 1904), pp. 461-466
* The Dream Becomes a Reality: The Discovery of Radium by Marie Sklodowska Curie; source: chapter five - Pierre Curie [1923]
* The Discovery of Radium by Marie Sklodowska Curie; source: Ellen S. Richards Monographs No. 2 (Poughkeepsie: Vassar College, 1921), n.p.

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Marie Curie” “Pierre Curie” “Polonium” “Radium”
1899

WHAT:
Actinium
* Naturally occurring element.

WHO:
Andre Debierne

HOW:
* Isolated from pitcheblende by means of its radioactivity.

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Andre Debierne” “Actinium”
1900

WHAT:
Gamma Rays
* A third component discovered in radioactivity

WHO:
Paul Villard

HOW:
* Electromagnetic deflection.
* Magnetic fields do not affect a part of the radioactivity but do cause both Alpha rays and Beta rays to be deflected.

NOTES:
* More penetrating that X-rays

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Paul Villard” “Gamma Rays”

WHAT:
Quantum Hypothesis

WHO:
Max Planck

HOW:
* Brains considering Black Body Radiation

NOTES:
* Atoms emit energy in discreet units, and not continuously.
* Introduces a new universal constant “h”, called Planck's constant.
* Will play a key role in the development of a new language to describe the subatomic world.

In their own words:
* On the Law of Distribution of Energy in the Normal Spectrum by Max Planck; source: Annalen der Physik, vol. 4, p. 553 ff (1901)
* The Genesis and Present State of Development of the Quantum Theory by Max Planck; source: Nobel Lecture, June 2, 1920

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Max Planck” “Quantum Hypothesis”

WHAT:
Radon
* Naturally occurring element.

WHO:
Friedrich Dorn

HOW:
* Demonstrated that Radium forms a gaseous element as it breaks down.

NOTES:
* A radioactive gas! that was something new.

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Friedrich Dorn” “Radon”
1902

WHAT:
Transmutation
* Every emission of radiation in radioactivity alters the emitting atom and turns it into an atom of another element.
* Radioactive decay series of Uranium, Thorium, and Actinium identified.

WHO:
Ernest Rutherford
Frederick Soddy

HOW:
* “A magnificent combination of physical and chemical techniques.”

NOTES:
* Beginnings of Isotope concept.
* Radioactivity is atomic disintegration.

In their own words:
* The Cause and Nature of Radioactivity by Ernest Rutherford and Frederick Soddy; source: Philosophical Magazine 4, 370-96 (1902)

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Ernest Rutherford” “Frederick Soddy” “Transmutation”
1905

WHAT:
Photon
* Elementary particle (still).
* The quantum of light energy.

WHO:
Albert Einstein

HOW:
* Brains considering the photoelectric effect and Planck's Quantum Hypothesis

NOTES:
* Metals exposed to ultraviolet light emit electrons.
* Light found behaving like particles, like discreet units of energy as opposed to continues waves.
* First of five revolutionary papers published in 1905, Einstein's Annus Mirabilis.

In their own words:
* Concerning an Heuristic Point of View Toward the Emission and Transformation of Light [PDF] by A. Einstein; source: Ann. Phys. 17, 132. Translation: American Journal of Physics, v. 33, n. 5, May 1965 [ http://spica.ihep.su/hist/owa/hw.part2?s_c=EINSTEIN+1905 ]
* On a Heuristic Point of View about the Creation and Conversion of Light [PDF] by A. Einstein; source: Ann. Physik 17, 132 (1905). [ http://lorentz.phl.jhu.edu/AnnusMirabilis/#common ]

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Albert Einstein” “Photon”

WHAT:
Special Theory of Relativity

WHO:
Albert Einstein

HOW:
* Brains seeking conservation laws.

NOTES:
* Time and space relative to velocity.
* Equivalence of energy and matter.
* Speed of light is universal constant for any frame of reference.
* End of “luminiferous ether,” the hypothetical medium of light wave propogation.
* End of Newtons' absolute time and space.

In their own words:
* On the Electrodynamics of Moving Bodies by A. Einstein; source: Annalen der Physik. 17:891, 1905
* Does the Inertia of a Body Depend on its Energy-Content? by A. Einstein; source: Annalen der Physik. 18:639, 1905
* Relativity: The Special and General Theory by Albert Einstein; source: New York: Henry Holt and Company, 1920. Translated by Robert W. Lawson.
* The History of Field Theory ("Olds and News of Field Theory") by Albert Einstein; source: (February 3, 1929) "presented to the general public"?
* Fundamental Ideas and Problems of the Theory of Relativity by Albert Einstein; source: Nobel Lecture, July 11, 1923

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Albert Einstein” “Special Theory of Relativity”
1908

WHAT:
Geiger Counter
* perfected in 1928

WHO:
Hans Geiger
Ernest Marsden
* working under Ernest Rutherford.

HOW:
* Inert gas in a strong electrical field

NOTES:
* Capable of registering the influence of a single particle.
* Records single ionizing event.

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Hans Geiger” “Ernest Marsden” “Geiger Counter”
1910

WHAT:
Atomic Nucleus
* Most of the mass of an atom resides in an incredibly small and dense, positively charged center, which is surrounded by atomic electrons.
* In the light of the nuclear model of the atom it became clear that the origin of all radioactive radiations, including beta, was the nucleus of the atom, since only a change in the nucleus could transform one element into another.

WHO:
Ernest Rutherford
* with experimental results of Hans Geiger and Ernest Marsden

HOW:
* Alpha Particle Probe: scattering on a thin gold foil; the positively charged particle is deflected as it interacts electromagnetically with the positively charged nucleus; deflection angle depends on nearnesss of approach and amount of nuclear charge.

NOTES:
* Chemical properties of atoms are determined by the number of electrons, which is, in turn, determined by the amount of positive charge in the nucleus.
* Made possible determination of the value of Z of the scattering atom, which explained the regularity of the empirically derived periodic chart; provides a structural explanation for the regularities. Chemical characteristics being determined by the number of electrons surrounding the nucleus.
* Throws an experimental wrench into the works of classical mechanics. Leads Niels Bohr to apply the curious new quantum theory to describe the orbits of the electrons.
* “It was quite the most incredible events that has ever happened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you. On consideration I realized that this scattering backwards must be the result of a single collision, and when I made calculations I saw that it was impossible to get anything of that order of magnitude unless you took a system in which the greatest part of the mass of the atom was concentrated in a minute nucleus” - Ernest Rutherford

In their own words:
* The Scattering of a and b Particles by Matter and the Structure of the Atom by E. Rutherford, F.R.S.; source: Philosophical Magazine, Series 6, vol. 21, May 1911, p. 669-688
* The Structure of the Atom by Ernest Rutherford; source: Philosophical Magazine, Series 6, Volume 27, March 1914, p. 488 - 498
* The Scattering of the a-Particles by Matter by H. GEIGER, Ph.D.; source: Proceedings of the Royal Society, vol. A83, p. 492-504
* On a Diffuse Reflection of the a-Particles by By H. GEIGER,and E. MARSDEN; source: Proc. Roy. Soc. 1909 A, vol. 82, p. 495-500
* The Laws of Deflexion of a Particles through Large Angles by H. GEIGER and E. MARSDEN; source: Philosophical Magazine, Series 6, Volume 25, Number 148, April 1913

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Ernest Rutherford” “Atomic Nucleus”

WHAT:
Cosmic Rays
* penetrating radiation incident on the atmosphere from outer space.

WHO:
Victor Hess

HOW:
* Carried an electroscope aloft up to 5,000 meters in a balloon and found that backgound ionization levels increased with altitude.

NOTES:
* Background ionization first imagined by C.T.R. Wilson as cause of unavoidable leaks of charge from electroscope.
* Range of energies has been found to be from a billion to ten quintillion electron volts.

In their own words:
* Unsolved Problems in Physics: Tasks for the Immediate Future in Cosmic Ray Studies by Victor F. Hess; source: Nobel Lecture, December 12, 1936

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1912

WHAT:
X-ray Diffraction
* proves electromagnetic nature of X-rays

WHO:
Max von Laue

HOW:
* Diffraction by crystals

NOTES:
* Makes possible measurement of wavelengths of X-rays.
* Allows for determination of structure of crystals in terms of the arrangements of the atoms that compose them.

In their own words:
* Concerning the Detection of X-ray Interferences by Max von Laue; source: Nobel Lecture, December 12, 1915

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Max von Laue” “X-ray Diffraction”

WHAT:
Cloud Chamber
* Paths of charged atomic particles made visible.

WHO:
C.T.R. Wilson

HOW:
* In a supersaturated gas, the ions left in the trail of an ionizing event act as condensation nuclei for water droplets.

NOTES:
* Reactions between atomic particles may be “seen” and photographed.
* Very useful in the discovery of new particles.
* Useful in later years for studying the effects of electrical and magnetic fields on particle motion; measuring ratios of charge to mass ...

In their own words:
* On the Cloud Method of Making Visible Ions and the Tracks of Ionizing Particles by C.T.R. Wilson; source: Nobel Lecture, December 12, 1927
* Nobel Banquet Speech by C.T.R. Wilson; source: Stockholm, December 10, 1927

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “C.T.R. Wilson” “Cloud Chamber”
1913

WHAT:
Isotopes
* Atoms dentical in chemical properties (having same nuclear charge) and differing only in atomic mass.

WHO:
Frederick Soddy

HOW:
* Established chemical identity of various decay change members.

NOTES:
* Radioactive Displacement Law: describes the resultant transformation of nuclei undergoing alpha and beta decay.

In their own words:
* The Radio-elements and the Periodic Law by Frederick Soddy; source: Chemical News 107, 97-9 (1913)
* Intra-atomic Charge by Frederick Soddy; source: Nature 92, 399-400 (December 4, 1913)
* Radioactivity by Frederick Soddy; source: Chemical Society Annual Reports 10, 262-88 (1913)
* The Origins of the Conception of Isotopes by Frederick Soddy; source: Nobel Lecture, December 12, 1922
* Radioactive Transformations and the Periodic System of The Elements by Kasimir Fajans; source: Berichte der Deutschen Chemischen Gesellschaft, Vol. 46, p. 422-439 (1913)

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Frederick Soddy” “Isotopes”

WHAT:
Atomic Number
* Explains the Periodic Table of the elements on the basis of nuclear charge.

WHO:
Henry Moseley
* Great promise for science was cut off when Moseley was killed at Gallipoli in World War One at the age of 28.

HOW:
* X-ray diffraction

NOTES:
* Determined the number of positive charges in the nucleus.

In their own words:
* The High Frequency Spectra of the Elements by H. G. J. Moseley, M. A.; source: Phil. Mag. (1913), p. 1024

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Henry Moseley” “Atomic Number”

WHAT:
Bohr Atom
* Rutherford-Bohr Atom Model
* Central nucleus orbited by electrons (the 20th century atom icon familiar in popular culture).

WHO:
Niels Bohr

HOW:
* Brains considering Rutherford's nucleus, Quantum Theory, along with spectroscopic emissions and characteristic X-rays, as well as Isaac Newton's classical mechanics

NOTES:
* “One must assume that there are forces in nature of a kind completely different from the usual mechanical sort”
- Niels Bohr

* Correspondence principal.
* Awesome explanatory power, providing a theoretical ground for a multitude of chemical phenomena known empirically, e.g., the periodic table of the elements.
* Incorporates Quantum Theory into description of atomic electrons.
* Elaborated by Sommerfeld.

In their own words:
* On the Constitution of Atoms and Molecules by Niels Bohr; source: Philosophical Magazine, Series 6, Volume 26, July 1913, p. 1-25
* Atomic Structure by Niels Bohr; source: Nature, March 24, 1921
* The Structure of the Atom by Niels Bohr; source: Nobel Lecture, December 11, 1922
* THE STRUCTURE OF ATOMS AND THE OCTET THEORY OF VALENCE by Irving Langmuir; source: Proceedings of the National Academy of Science, Vol. V, 252 (1919)

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Niels Bohr” “Bohr Atom”

WHAT:
Radioactive Tracer
* first use

WHO:
George de Hevesy
* jointly with Frederic Paneth

HOW:
* Uses radioactive isotopes to “see” physiological processes and chemical pathways.

NOTES:
* Used neutron activation to synthesize isotopes of biologically active elements, first: radiophosphorus.

In their own words:
* Some Applications of Isotopic Indicators by George de Hevesy; source: Nobel Lecture, December 12, 1944

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1919

WHAT:
Proton
* The nuclear carrier of positive charge; fundamental building block of all atoms.
Artificial Transmutation
* First human made nuclear transformation.

WHO:
Ernest Rutherford
James Chadwick

HOW:
* Alpha particle bombardment converts Nitrogen into Oxygen and releases a Proton

NOTES:
* Between 1920 and 1925 alpha particle bombardment of boron, flourine, neon, sodium and other elements, in all cases caused release of a hydrogen nucleus; lead to conclusion that it was one of the fundamental building blocks of all other nuclei.
* Change of one type of atom into another: nuclear change.
* Beginning of many bombardment experiments probing internal structure of the nucleus.
* Leads to particle accelerator.

In their own words:
* Collisions of alpha Particles with Light Atoms. IV. An Anomalous Effect in Nitrogen. by Sir Ernest Rutherford; source: The London, Edinburgh and Dublin Philosophical Magazine and Journal of Science, 6th series, 37, 581 (1919)
* Bakerian Lecture: Nuclear Constitution of Atoms by Sir Ernest Rutherford; source: Proc. Roy. Soc. A, 97, 374 (1920)

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Ernest Rutherford” “James Chadwick” “Proton” “Artificial Transmutation”
1922

WHAT:
Compton Effect
* Scattering of X-rays by electrons.

WHO:
Arthur Compton

HOW:
* Observed photons imparting energy to electrons as if by collision, wavelength decreases.

NOTES:
* Electromagnetic photons display both particle and wavelike behavior; photons have no mass, but do have momentum.

In their own words:
* X-rays as a Branch of Optics by Arthur H. Compton; source: Nobel Lecture, December 12, 1927

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Arthur Compton” “Compton Effect”
1924

WHAT:
Bose-Einstein Statistics

WHO:
S.N. Bose
Albert Einstein

HOW:
* Development and application of statistical mechanics to subatomic phenomena.

NOTES:
* Invented to describe the behavior of photons and ensembles of such as groups of electrons and molecules.

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “S.N. Bose” “Albert Einstein” “Bose-Einstein Statistics”

WHAT:
Wave Equation
* for electrons
* The electron is a wave too!

WHO:
Louis de Broglie

NOTES:
* “Wavicles” very counter-intuitive, not actual physical quantity, rather it is a complex number.
* Accounts for N. Bohr's quantization of electron orbits.
* At subatomic dimensions, all particles have been shown to have wave properties/wave-nature, and vice versa; this explains the permissible states for electrons in the Bohr atom.

In their own words:
* RADIATION — Waves and Quanta by Louis de Broglie; source: presented by Jean Perrin (Translated from Comptes rendus, Vol. 177, 1923, pp. 507-510)
* The Wave Nature of the Electron by Louis de Broglie; source: Nobel Lecture, December 12, 1929

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Louis de Broglie” “Wave Equation”

WHAT:
Quantum Matrix Mechanics

WHO:
Werner Heisenberg
Max Born
Pascual Jordan

HOW:
* Brains and “pure” mathematics developed in 1800s
* Matrix algebra

NOTES:
* A purely mathematical representation/description of electrons.
* Leads to Heisenberg's famous “uncertainty principle,” saying that an electron's exact position and it's velocity cannot be determined at the same time, implying that in the subatomic world causality breaks down. No precise predictions possible of where an individual electron is, only statistical statements are possible, likeliness. Probability is introduced into the basic laws of nature permanently (?).
* “[In quantum mechanics] we free forces of their classical duty of determining directly the motion of particles and allow them instead to determine the probability of states.” - Max Born

In their own words:
* The Development of Quantum Mechanics by Werner Heisenberg; source: Nobel Lecture, December 11, 1933
* Speech at the Nobel Banquet by Max Born; source: Stockholm, December 10, 1954
* The Statistical Interpretations of Quantum Mechanics by Max Born; source: Nobel Lecture, December 11, 1954
* by ; source:

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Werner Heisenberg” “Max Born” “Pascual Jordan” “Quantum Matrix Mechanics”
1926

WHAT:
Fermi-Dirac Statistics

WHO:
Enrico Fermi
P.A.M. Dirac
* Working independently.

NOTES:
* Invented to describe the behavior of protons, neutrons and electrons, particles now known as fermions

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “Enrico Fermi” “P.A.M. Dirac” “Fermi-Dirac Statistics”
1927

WHAT:
Quantum Wave Mechanics
* Non-relativistic Quantum Mechanics

WHO:
Erwin Schrödinger

HOW:
* Mathematical articulation of L. de Broglie waves for electrons and atoms.

NOTES:
* The Schrödinger Equation = Quantum Wave Equation
* Electrons considered as probability wave functions.
* Schrödinger later proves the equivalence with Quantum Mechanics of Heisenberg.

In their own words:
* The Fundamental Idea of Wave Mechanics by Erwin Schrödinger; source: Nobel Lecture, December 12, 1933

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WHAT:
High Energy Physics
* Observes cosmic ray particles with energies greatly exceeding those of natural radioactivity.
* First observation of cosmic ray showers.

WHO:
D.V. Skobeltsyn

HOW:
* Cloud Chamber in magnetic field.

NOTES:
* Birth of High Energy Particle Physics.
* Discovered the nature of cosmic rays, i.e., heavy nuclei.

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “D.V. Skobeltsyn” “High Energy Physics”
1928

WHAT:
Relativistic Quantum Mechanics
* Relativistic Wave Equation
* Antimatter Hypothesis

WHO:
P.A.M. Dirac

HOW:
* Combines all the ideas of de Broglie, Schrodinger, Heisenberg and Born with Einstein's theory of relativity.

NOTES:
* “The crowning achievement of theoretical physics.” (?)
* “spin”
* Predicts positron, as well as anti-particles for every other charged particle.
* Predicts pair-production, positron and electron produced from photon with energy greater than 1.002 million electron volts (double the rest mass of the electron), which illustrates the equivalence of mass and energy!
* Provides the most precise conceptual tool for describing the physical world; the irony is that it is incomprehensible: any picture you can illustrate this theory with is incomplete and potentially misleading.

In their own words:
* Theory of Electrons and Positrons by Paul A.M. Dirac; source: Nobel Lecture, December 12, 1933
* Nobel Banquet Speech by Paul A.M. Dirac; source: Stockholm, December 10, 1933

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “P.A.M. Dirac” “Relativistic Quantum Mechanics”
1929

WHAT:
Particle Accelerator
* Cockcroft/Walton accelerator
* First high-voltage particle accelerater.

WHO:
John Cockroft
Ernest Walton

HOW:
* High tension tube.
* Large electrical potenial difference.

NOTES:
* Transmutation experiments carried out.
* Accelerates hydrogen atoms to one to two million electron volts.

In their own words:
* The Artificial Production of Fast Particles by Ernest T.S. Walton; source: Nobel Lecture, December 11, 1951
* Experiments on the Interaction of High-Speed Nucleons with Atomic Nuclei by John Cockcroft; source: Nobel Lecture, December 11, 1951
* Nobel Banquet Speech by John Cockcroft; source: Stockholm, December 10, 1951

SEARCH: google . google images || wikipedia || yahoo . yahoo images >>> TERMS: “John Cockroft” “Ernest Walton” “Particle Accelerator”
1930

WHAT:
Neutrino Hypothesis

WHO:
Wolfgang Pauli

HOW:
* Brains considering the apparent violation of energy conservation in beta decay spectrum.

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1931

WHAT:
Cyclotron

WHO:
Ernest Lawrence

HOW:
* Accelerates particles in successive pulses along a spiral trajectory.

NOTES:
* Opened the way to ever more powerful accelerators.

In their own words:
* The Evolution of the Cyclotron by Ernest Lawrence; source: Nobel Lecture, December 11, 1951
* Nobel Banquet Speech by Ernest Lawrence; source: Berkeley, February 29, 1940

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1932

WHAT:
Neutron
* Uncharged particle of approximately same mass as a proton.
* Essential constituent of all atoms.

WHO:
James Chadwick
* following up on inconclusive experiments of 1930 by W. Bothe and H. Becker, and of 1932 by Irčne Curie and Frédéric Joliot
*

HOW:
* Bombarding beryllium with alpha particles released neutrons whose mass was deduced from the amount of energy it imparted to other nuclei.
* No direct study of the electrically neutral particle possible.

NOTES:
* “The discovery of the neutron is a classical example of the way in which the addition of a new building block clarifies as if by magic many previously inexplicable facts.”(?) For example, the mass number, A, is just the total number of protons and neutrons in the nucleaus; explained the puzzle of atomic weights and numbers and solved the problem of isotopes.
* It seemed that the picture of the subatomic world was complete with photons, electrons, protons and neutrons.
* Different isotopes of an element are atoms with nuclei containing the same number of protons but different numbers of neutrons.
* Initially predicted by E. Rutherford in the 1920s.
* Replaces model where nucleus is made of of protons and electrons with a proton-neutron model.
* F. Soddy developed the isotope theory before neutrons were discovered!
* Brings up the question of what holds the nucleus together since charges of the same sign repel one another(Answer: a unique nuclear force: The Strong Force).

In their own words:
* Possible Existence of a Neutron by James Chadwick; source: Nature, p. 312 (Feb. 27, 1932)
* The Existence of a Neutron by J. Chadwick, F.R.S.; source: Proc. Roy. Soc., A, 136, p. 692-708 (Received May 10, 1932)
* The Neutron and Its Properties by James Chadwick; source: Nobel Lecture, December 12, 1935

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WHAT:
Positron
* Another fundamental particle.
* The positive electron; the electron's anti-particle

WHO:
Carl D. Anderson

HOW:
* Source: secondary cosmic rays.
* Detector: cloud chamber in strong magnetic field.
* Curvature in magnetic field equal but opposite to that of electron.

NOTES:
* First predicted mathematically by P.A.M. Dirac (1928).

In their own words:
* The Production and Properties of Positrons by Carl D. Anderson; source: Nobel Lecture, December 12, 1936
* Nobel Banquet Speech by Carl D. Anderson; source: Stockholm, December 10, 1936
* Interview with Carl Anderson by Carl D. Anderson interviewed by Harriett Lyle, 1979; source: Oral History Project, California Institute of Technology Archives, Pasadena, California.

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WHAT:
Pair Production
* Positron/Electron pair produced from photon.
* Also observed cosmic ray showers, or cascades.

WHO:
Patrick Blackett
Giuseppe Occhialini

HOW:
* Combining Occhialini's coincidence counters, developed by Rossi in Italy, with Blackett's cloud chambers for high altitude studies of cosmic rays.

NOTES:
* First predicted mathematically by P.A.M. Dirac (1928).

In their own words:
* Cloud Chamber Researches in Nuclear Physics and Cosmic Radiation by Patrick M.S. Blackett; source: Nobel Lecture, December 13, 1948
* Nobel Banquet Speech by Patrick M.S. Blackett; source: Stockholm, December 10, 1948
* The Coincidence Method by Walther Bothe; source: Nobel Lecture [1954]

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1934

WHAT:
Neutron Bombardment

WHO:
Enrico Fermi

HOW:
* Neutral charge allows neutron to easily penetrate nuclei without electrical repulsion from protons or electrons.

NOTES:
* Succeeded in making artificial radioactive isotopes of most known nuclei using slow neutrons. These isotopes become important as tracers in medicine and industry.
* Bombarding an element with the newly discovered subatomic particle often transforms the element into the element of the next higher atomic number.

In their own words:
* Possible Production of Elements of Atomic Number Higher than 92 by E. Fermi; source: Nature, 133, p. 898-899 (1934)
* Artificial Radioactivity Produced by Neutron Bombardment by Enrico Fermi; source: Nobel Lecture, December 12, 1938

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WHAT:
Artificial Radioactivity

WHO:
Irčne Curie
Frédéric Joliot

HOW:
* Certain elements irradiated with alpha rays continued to emit radiation even after the irradiating source was removed. In earlier experiments conducted since 1919 the radioactivity ceased instantly when the inducing radiation was stopped.

NOTES:
* Artificial radioactive isotopes are now produced on a large scale in nuclear reactors for use in medicine and industry.

In their own words:
* Artificial Production of Radioactive Elements by Irčne Joliot-Curie; source: Nobel Lecture, December 12, 1935
* Chemical Evidence of the Transmutation of Elements by Frédéric Joliot; source: Nobel Lecture, December 12, 1935

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1935

WHAT:
Meson
* predicted mathematically.

WHO:
Hideki Yukawa

HOW:
* Brains considering what force is needed to hold together protons and neutrons in a nucleus.

NOTES:
* The quantum of the strong force: exchange boson carrier of the strong force.

In their own words:
* Meson Theory in Its Developments by Hideki Yukawa; source: Nobel Lecture, December 12, 1949

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1936

WHAT:
Muon
* first called “mesotron”

WHO:
Carl Anderson
Seth Neddermeyer

HOW:
* Cosmic ray observations with cloud chamber in powerful magnetic field.
* Range of penetration used to estimate energy; speed indicated by thickness of the tails of ions.

NOTES:
* At first, thought to be H. Yukawa's meson (1935).

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WHAT:
Induced Fission
Transuranic Elements

WHO:
Enrico Fermi

HOW:
* Bombarding heavy elements with neutrons.

NOTES:
* Produced elements heavier than any found naturally occurring.

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1937

WHAT:
Nuclear Fission
* Splitting the atom.

WHO:
Otto Hahn
Fritz Strassman
* Explained later by Lise Meitner and Otto Frisch (1939)

HOW:
* Irradiating uranium with slow neutrons splits nucleus into a number of light fragments. Barium found among the reaction products.

NOTES:
* Releases large amounts of energy.

In their own words:
* Concerning the Existence of Alkaline Earth Metals Resulting from Neutron Irradiation of Uranium by O. Hahn AND F. Strassman; source: Die Naturwissenschaften 27, p. 11-15 (January 1939). [Transl. in American Journal of Physics, January 1964, p. 9-15]
* Proof of the Formation of Active Isotopes of Barium from Uranium and Thorium Irradiated with Neutrons; Proof of the Existence of More Active Fragments Produced by Uranium Fission by Otto Hahn and Fritz Strassmann; source: Die Naturwissenschaften, Volume 27, No. 6, pp. 89-95 (10 February 1939) [Transl. from Journal of Chemical Education, May 1989, p. 363-363]
* Disintegration of Uranium by Neutrons: a New Type of Nuclear Reaction by Lise Meitner and O.R. Frisch; source: Nature, 143, 239-240, (Feb. 11, 1939)
* Physical Evidence for the Division of Heavy Nuclei under Neutron Bombardment by 0. R. Frisch; source: Nature (London), Volume 143, p. 276 (1939)
* The Discovery of Fission by Otto Frisch and John Wheeler; source: Physics Today, p. 43, November 1937

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1938

WHAT:
Chain Reaction
* the possibility

WHO:
Irčne Curie
Frédéric Joliot

HOW:
* Bombarding uranium with neutrons.

NOTES:
* Fission, splitting of atom with the release of more neutrons that can go on to induce more fission.
* uncontrolled = explosion; controlled = energy-producing pile.

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1940

WHAT:
Neptunium
* synthesized element

WHO:
Edwin McMillan
Philip Abelson

HOW:
* Produced in cyclotron by neutron bombardment.

NOTES:
* First transuranic element produced.

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1942

WHAT:
Atomic Energy
* Controlled fission of uranium; sustained nuclear chain reaction.

WHO:
Enrico Fermi

HOW:
* Atomic Pile: critical mass assembly of uranium -235

NOTES:
* Ushers in the Atomic Age.
* Heat generated by fission can be used to produce steam to drive generators.

In their own words:
* THE FIRST ATOMIC FILE: An Eyewitness Account Revealed by Some of the Participants and Narratively Recorded by Corbin Allardice and Edward R. Trapnell; source: The U.S. Atomic Energy Commission, Washington, D.C., November 1949

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WHAT:
Plutonium
* synthesized transuranic element

WHO:
Glenn Seaborg
Edwin McMillan
Joseph Kennedy
Arthur Wahl

HOW:
* Produced in cyclotron bombardment.
* Extracted by radiochemical techniques.

In their own words:
* The Transuranium Elements: Early History by Edwin M. McMillan; source: Nobel Lecture, December 12, 1951
* The Transuranium Elements: Present Status by Glenn T. Seaborg; source: Nobel Lecture, December 12, 1951

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1945

WHAT:
Atomic Bomb
* Uncontrolled fission chain reaction.
*

WHO:
J. Robert Oppenheimer
* leading the Manhattan Project

HOW:
* A massive feat of technology and scientific administration; organized effort of some 500,000 people costing a billion dollars per year.

NOTES:
* “represents another major leap forward in man's control of natural forces of the same order as, and possibly of greater ultimate importance than, those of fire, agriculture, and steam.” (?)

In their own words:
* Los Alamos Conference Summary by Oppenheimer, Manley, Fermi, Bethe; source: 15-24 April 1943
* The Atomic Bombings of Hiroshima and Nagasaki by The Manhattan Engineer District; source: June 29, 1946
* The Effects of Nuclear Weapons by Compiled and edited by Samuel Glasstone and Philip J. Dolan; source: Third Edition, Prepared and published by the United States Department of Defense and the Energy Research and Development Administration, 1977.
* Atomic Energy for Military Purposes by Henry De Wolf Smyth; source: The Official Report on the Development of the Atomic Bomb Under the Auspices of the United States Government (July 1945)

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1947

WHAT:
Ilford Photographic Plates
* “Nuclear Research Emulsions”
* Refinement of emulsions gives more subtle measurement capability.

WHO:
Cecil Powell
* with Giuseppe Occhialini, et al

HOW:
* The atomic mass of particles passing through can be obtained by measuring the density of the small black dots which form the track, and from deviations caused by collisions with nuclei in the emulsion. The slower the particle, the more atoms ionized and the greater density of the dots; direction, energy and rate of energy loss can be estimated.

NOTES:
* “It was as if, suddenly, we had broken into a walled orchard, where protected trees had flourished and all kinds of exotic fruits had ripened in great profusion.” - C. Powell on the world of subatomic particles revealed in cosmic rays using the new emulsions.

In their own words:
* The Cosmic Radiation by Cecil Powell; source: Nobel Lecture, December 11, 1950
* Nobel Banquet Speech by Cecil Powell; source: Stockholm, December 10, 1950

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WHAT:
Pion
* The meson predicted by H. Yukawa in 1935.

WHO:
Cecil Powell
* with Giuseppe Occhialini, et al

HOW:
* Source: cosmic rays.
* Detector: Ilford Photographic Plates, new, more sensitive photographic emulsions that overcame problems of low ionization rate of high energy particles and allowed for identification of primary cosmic rays.

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1952

WHAT:
Bubble Chamber

WHO:
Donald Glaser
* with Louis Alvarez

HOW:
* Sudden reduction of the pressure above a liquid close to its boiling point lowers the boiling point of the liquid and a situation of 'super-heating' is created where the temperature of the liquid is higher that its boiling point. If an ionizing particle passes now, bubbles of gas form around the ions, marking the path of the particle.

NOTES:
* Rumor: Glaser was inspired by a bottle of beer.
* Became most widely used detectors in the search for new particles.
* Great advantage: density of the liquid is greater than that of the gas in a cloud chamber, so particles are more often stopped within the chamber, permitting the entire path to be photographed.

In their own words:
* Elementary Particles and Bubble Chambers by Donald A. Glaser; source: Nobel Lecture, December 12, 1960
* Recent Developments in Particle Physics by Luis Alvarez; source: Nobel Lecture, December 11, 1968
* Interview with Professor Donald Glaser by Professor Anders Bárány; source: Video of meeting of Nobel Prize Winners in Lindau, Germany, 2000.

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WHAT:
Thermonuclear Bomb
* Hydrogen Bomb; Fusion Bomb

WHO:
Edward Teller
* et al

In their own words:
* General Advisory Committee's Majority and Minority Reports on Building the H-Bomb by J. Robert Oppenheimer, E. Fermi, I.I. Rabi, et al; source: October 30, 1949
* Comments on the History of the H-Bomb (PDF 1.51 MB) by Hans Bethe; source: Los Alamos Science, Fall 1982, Vol. 3, Num. 3

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