5 Nobel Lectures Joseph John Thomson (1856-1940) Carriers of negative electricity Nobel Lecture in Physics, December 11, [from Introductory In this lecture I wish to give an account of some investigations which have led to the conclusion that the carriers of negative electricity are bodies, which I have called corpuscles, having a mass very much smaller than that of the atom of any known element, and are of the same character from whatever source the negative electricity may be derived. The first place in which corpuscles were detected was a highly exhausted tube through which an electric discharge was passing. When an electric discharge is sent through a highly exhausted tube, the sides of the tube glow with a vivid green phosphorescence. That this is due to something proceeding in straight lines from the cathode--the electrode where the negative electricity enters the tube--can be shown in the following way (the experiment is one made many years ago by Sir William Crookes): A Maltese cross made of thin mica is placed between the cathode and the walls of the tube. When the discharge is past, the green phosphorescence no longer extends all over the end of the tube, as it did when the cross was absent. There is now a well-defined cross in the phosphorescence at the end of the tube; the mica cross has thrown a shadow and the shape of the shadow proves that the phosphorescence is due to something travelling from the cathode in straight lines, which is stopped by a thin plate of mica. The green phosphorescence is caused by cathode rays and at one time there was a keen controversy as to the nature of these rays. Two views were prevalent: one, which was chiefly supported by English physicists, was that the rays are negatively electrified bodies shot off from the cathode with great velocity; the other view, which was held by the great majority of German physicists, was that the rays are some kind of ethereal vibration or waves. The arguments in favour of the rays being negatively charged particles are primarily that they are deflected by a magnet in just the same way as moving, negatively electrified particles. We know that such p
7 THE DREAM BECOMES A REALITY THE DISCOVERY OF RADIUM by Marie Curie I HAVE already said that in 1897 Pierre Curie was occupied with an investigation on the growth of crystals. I myself had finished, by the beginning of vacation, a study of the magnetization of tempered steels which had resulted in our getting a small subvention from the Society for the Encouragement of National Industry. Our daughter Ir鈩e was born in September, and as soon as I was well again, I resumed my work in the laboratory with the intention of preparing a doctor's thesis.Our attention was caught by a curious phenomenon discovered in 1896 by Henri Becquerel. The discovery of the X-ray by Roentgen had excited the imagination, and many physicians were trying to discover if similar rays were not emitted by fluorescent bodies under the action of light. With this question in mind Henri Becquerel was studying uranium salts, and, as sometimes occurs, came upon a, phenomenon different from that he was looking for: the spontaneous emission by uranium salts of rays of a peculiar character. This was the discovery of radioactivity.The particular phenomenon discovered by Becquerel was as follows: uranium compound placed upon a photographic plate covered with black paper produces on that plate an impression analogous to that which light would make. The impression is due to uranium rays that traverse the paper. These same rays can, like X-rays, discharge an electroscope, by making the air which surrounds it a conductor.Henri Becquerel assured himself that these properties do not depend on a preliminary isolation, and that they persist when the uranium compound is kept in darkness during several months. The next step was to ask whence came this energy, of minute quantity, it is true, but constantly given off by uranium compounds under the form of radiations.The study of this phenomenon seemed to us very attractive and all the more so because the question was entirely new and nothing yet had been written upon it. I decided to undertake an investigation of it. It was necessary to find a place in which to conduct the experiments. My husband obtained from the director of the School the authorization to use a glassed-in study on the ground floor which was then being used as a storeroom and machine shop.
8 Descoberta de Partículas a e b E. Rutherford - 1989 Earnest Rutherford
9 As primeiras idéias.."The cause and origin of the radiation continuously emitted by uranium and its salts still remain a mystery. All the results that have been obtained point to the conclusion that uranium gives out types of radiation which, as regards their effects on gases, are similar to Röntgen rays and the secondary radiation emitted by metals when Röntgen rays fall upon them. If there is no polarization or refraction the similarity is complete."
10 Destinção de a, b, gAinda no ano 1900, não há magnet que pode desviar o “raio alfa’’ emitido do Urânio. Rutherford em 1903, conseguiu mostrar com magnet mais forte na epoca e também com o campo elétrico, o desvio do raio alfa, e portanto concluindo como feixe de partícula carregada.
11 1900 Descoberta de g Paul Villard Identificado como radiação eletromagnética em 1914 por E. Rutherford
12 Abertura da nova era Max Planck 1858 - 1947 1900 Introdução de constante hPremio Nobel 1918Annus Mirabilis / A. EinsteinEfeito fotoelétricoMovimento BrownianoRelatividade RestritaPremio Nobel 1921
13 1908 Experimento de espalhamento de alfa por Au
15 1H. Geiger and E. Marsden, Roy. soc. Proc. vol. lxxxii. p. 495 (1909) 1H. Geiger and E. Marsden, Roy. soc. Proc. vol. lxxxii. p. 495 (1909). 2E. Rutherford, Phil. Mag. vol. xxi. p. 669 (1911).From the distribution obtained, the most probable angle of scattering could be deduced, and it was shown that the results could be explained on the assumption that the deflexion of a single a particle is the resultant of a large number of very small deflexions caused by the passage of the a particle, through the successive individual atoms of the scattering substance.In an earlier paper1, however, we pointed out that a particles are sometimes turned through very large angles. This was made evident by the fact that when a particles fall on a metal plate, a small fraction of them, about 1/1800 in the case of platinum, appears to be diffusely reflected. This amount of reflection, although small, is, however, too large to be explained on the above simple theory of scattering. It is easy to calculate from the experimental data that the probability of a deflection through an angle of 90° is vanishingly small and different order to the value found experimentally
16 1909 Robert Millikan Medida da carga de elétron Premio Nobel 1923
18 Espectro Contínuo de Eletron num decaimento beta J. Chadwick ( )Estabelecimento de conceito sobre existência de proton esua identidade como nucleo de hidrogênioWienJ.J. ThomsonExperimento de Rutherford
19 Niles Bohr ( )On the Constitution of Atoms and Molecules, Philosophical Magazine, and Journal of SciencePremio Nobel em 1922A. Sommerfeld (1868 – 1951)Generalização do modelo do Bohr. Surgimento da Velha Mecânica Quântica
20 A. H. ComptonA Quantum Theory of the Scattering of X-rays by Light ElementsWashington University, Saint LouisPhys. Rev. 21, 483 (1923)Received 13 December 1922Premio Nobel 1927Charls T. Wilson ( )Invenção de Camara de WilsonPremio Nobel 1927Louis Victor deBroglie ( )1924 Tese de Doutoramento, Recherches sur la Théorie des Quanta, Univ. ParisPremio Nobel 1929
21 1927 Princípio de incerteza Premio Nobel em 1932 W. Heisenberg ( )1925 "My entire meagre efforts go toward killing off and suitably replacing the concept of the orbital paths that one cannot observe.."1927 Princípio de incertezaPremio Nobel em 1932M. Born ( )1925 Born-Jordan Z. fur Physik 34 (1925) 8581928 Interpretação probabilisticaPremio Nobel em 1954Pascual Jordan
22 1927 Princípio de incerteza Premio Nobel em 1932 Ervin Schrödinger ( )1926 Equação de Schrödinger1927 Princípio de incertezaPremio Nobel em 1932Paul Adrien Maurice Dirac ( )Tese “Quantum Mechanics”Relativistic Electron Theory1930 Teoria de buracos, previsão de positron1930 Principles of Quantum MechanicsPremio Nobel em 1932
23 Phone call from Copenhagen to Berlin, 1926: Niels Bohr:Erwin, I don't get it. Here I had a nice model that explains so much about the light spectrum, black body radiation, the periodic table of elements -- all the chemists were so excited and, besides, it just looks so cool and drawable. I can see high school teachers way in the future drawing little balls in the center with beads of electrons zipping around. What are you doing messing in with your waves?Erwin Schrodinger:Niels, you gotta be kidding. Everyone knows your model violates all the traffic laws of nature. You've taken old man Planck's quantum leaps one leap too far. Particles jumping from one orbit to another without traversing the space in between! I mean, if something can leave one place and turn up instantaneously in another, then anything could happen! And if anything could happen, then what are we scientists for?Niels:Okay, so it's weird. Life is weird, Erwin. And waves don't make it any less so.Erwin:Oh, yeah? Waves are the classic model for all energy forms. Water waves. Sound waves. Force waves. Light waves. That's the way we've been explaining energy for years and you crazy Danes have no right to change it!Waves in water I get. Same with waves in the air. But waves in an atom are downright ludicrous! You can't have waves without something waving, Erwin!A detail. So you caught me on a detail. Look, we figured everything else out. We'll figure this one out eventually as well. The main thing is we got rid of those doggone quantum disappearing acts.So waves in the nothingness is okay. But disappearing acts are not. Now if that isn't arbitrary…Niels, your buddy Albert already established that energy and matter are really the same stuff. So let's just do away with this whole notion of matter and tiny beads in orbit and say the whole world is made of energy. And energy is waves.Now there's no such thing as matter. So exactly who's going too far here? And another thing I want to know: If there aren't any electron particles, why is it my Geiger counter registers a click when they hit? Waves don't click, you know that Erwin. They splash or buzz, but they don't click. And how do you explain the whole black body radiation thing?You are the one going too far, Niels. Because I know just where you're going with all this. First you have them disappearing from one place and appearing elsewhere. Then you'll tell us they could be anywhere, their position and velocity is just an array of possibilities. And if they could be anywhere, then all of causality breaks down. I know what your pet whippersnapper student, Heisenberg is up to, Niels. No longer will we be able to say that this happened because that happened. And if all those things are gone, then, gevald Niels! Why are we scientists?Listen, Niels, electrons are energy. Energy is waves. Waves are the wave of the future. You got problems with it, go work it out. But don't go tearing down the basic laws of physics with particles that act like ghosts.They're particles.They're waves.Particles.In the name of the Motherland, they are waves!Your Motherland wears army boots. Now get your tushy up here to Copenhagen and we'll have it out like men, face to face.Danishes at two feet?Math at ten inches.
24 Satyendra Nath Bose1920 Dedução de Distribuição de PlanckUsando a estatistica de partícuas identicas1925 Einstein publica o artigo.Subrahmanyan Chandrasekhar ( )1930 Limit de ChandrasekharEddington – No such things....Premio Nobel em 1983
25 Wolfgang Pauli (1900-1958) Enrico Fermi (1901-1954) 1924 Proposta de Princípio de Exclusão, Grau de liberdade de spin1926 decução de espectro de hidrogênio usando a teoria de Heisenberg1927 Invenção de Matrizes de Pauli1930 Proposta de partícula neutra não observãvel no decaimento de beta.1940 Prova de teorema de Spin-estatisticaPremio Nobel em 1945Enrico Fermi ( )1926 Estatistica de Fermi1934 Construção de Teoria de decaimento beta, Fermi interactionPremio Nobel em Reações nucleares com neutrons
27 Início de Física Nuclear 1932 Descoberta de neutronsJames Chadwick ( )1932 Trabalhos de Heisenberg sobre a estrutura nuclear
28 Relatividade e Mecanica Quântica Positron1930 P.A. M. DiracCarl D. Anderson ( )Physical Review 43, 491 (1933).
29 Os primeiros passos de Teoria Quantica de Campos 1937 Propsta de píons para explicar aforça nuclearHideki Yukawa ( )
30 Descobertas de partículas novas 1937 J. C. Street and E. C. Stevenson"New Evidence for the Existence of a ParticleIntermediate Between the Proton and Electron"Phys. Rev. 52, 1003 (1937). -> muonDescobertas de pion1947 G.Ochialini, C. Lattes, C. Powell,Cesar Lattes( )
31 Início da era de acceleradores KeV Cockroft-Walton (Cavendish Lab)