From X-rays to the Bomb

8 Nov 1895 – 9 Aug 194576 items

physicswar
The Trinity fireball seconds after 05:29:45 on 16 July 1945, the only well-exposed colour photograph of the test. Photo: Jack W. Aeby, Los Alamos. Public domain, via Wikimedia Commons.
The Trinity fireball seconds after 05:29:45 on 16 July 1945, the only well-exposed colour photograph of the test. Photo: Jack W. Aeby, Los Alamos. Public domain, via Wikimedia Commons.

Fifty years from a glowing screen to a desert dawn

On 8 November 1895 a physicist in Würzburg saw a screen glow across a dark room. On 16 July 1945 a plutonium sphere turned a New Mexico desert to glass. In between, a few hundred people in a few dozen laboratories found the electron, the nucleus and the neutron, learned that one element can become another, and in the winter of 1938 found that uranium splits in two.

How it is built

The first four decades read at the scale of years, one discovery after another. Zoom into the winter of 1938–39 to follow fission from Hahn’s letter to Meitner’s paper week by week; into 2 December 1942 to watch Chicago Pile-1 go critical hour by hour; and into the dawn of 16 July 1945 for Trinity to the second. Hiroshima and Nagasaki close it as an epilogue. Bands mark the laboratories and programmes: Rutherford’s Manchester and Cambridge, Fermi’s Rome, the émigré exodus, the German Uranverein, Japan’s Ni-Go project, the raids on Norway’s heavy water and the Manhattan Project.

Threads to follow

  • x-rays: Röntgen’s rays and what they opened

  • radioactivity: Becquerel, the Curies, Rutherford, Fermi

  • atoms: electron, nucleus, quantum orbits, neutron

  • nuclear: fission, the chain reaction and the bomb

  • women: Curie, Meitner, Noddack, Joliot-Curie, Wu and the calutron operators

  • exile: the refugees who carried the physics west

Times are UTC; the notes give the local clock. Death tolls come from named sources with the ranges they give, and deaths by the end of 1945 are kept apart from later ones.

…it is conceivable — though much less certain — that extremely powerful bombs of a new type may thus be constructed. — Albert Einstein to Franklin D. Roosevelt, 2 August 1939

Items

  1. Röntgen sees a screen glow

    Physical Institute, Röntgenring 8, Würzburg

  2. “On a New Kind of Rays”

  3. Becquerel’s uranium rays

    Muséum national d’histoire naturelle, Paris

  4. Thomson’s corpuscles

    Royal Institution, Albemarle Street, London

  5. Polonium

    School of Physics and Chemistry (ESPCI), rue Lhomond, Paris

  6. Rutherford at McGill

    ≈ 8 years, 8 months · Macdonald Physics Building, McGill University, Montreal

  7. Radium

    School of Physics and Chemistry (ESPCI), rue Lhomond, Paris

  8. Rutherford names alpha and beta rays

  9. Rutherford and Soddy: elements transmute

    Macdonald Physics Building, McGill University, Montreal

  10. A Nobel for Becquerel and the Curies

  11. Einstein: mass is energy

  12. Rutherford at Manchester

    ≈ 11 years, 11 months · Physical Laboratories, Coupland Street, University of Manchester

  13. Geiger and Marsden: some alphas bounce back

    Physical Laboratories, Coupland Street, University of Manchester

  14. Rutherford’s nuclear atom

    Manchester Literary and Philosophical Society, George Street

  15. Bohr’s quantum atom

  16. Moseley counts the elements with X-rays

  17. The First World War

    ≈ 4 years, 3 months

  18. The Cavendish under Rutherford

    ≈ 18 years, 6 months · Cavendish Laboratory, Free School Lane, Cambridge

  19. Rutherford turns nitrogen into oxygen

    Physical Laboratories, Coupland Street, University of Manchester

  20. Bohr’s institute opens

    Institute for Theoretical Physics, Blegdamsvej 17, Copenhagen

  21. Chadwick finds the neutron

    Cavendish Laboratory, Free School Lane, Cambridge

  22. Cockcroft and Walton split lithium

    Cavendish Laboratory, Free School Lane, Cambridge

  23. The émigré exodus

    ≈ 6 years, 4 months

  24. Szilárd imagines a chain reaction

    Southampton Row at Russell Square, London

  25. The Joliot-Curies make radioactivity

    Institut du Radium, rue Pierre-Curie, Paris

  26. Fermi’s group in Rome

    ≈ 4 years, 8 months · Physics Institute, Via Panisperna 89a, Rome

  27. Fermi reports element 93

  28. Marie Curie dies

    Sancellemoz sanatorium, Passy, Haute-Savoie

  29. Ida Noddack: the nucleus might break up

  30. Slow neutrons

  31. Meitner escapes Berlin

    Kaiser Wilhelm Institute for Chemistry, Thielallee 63, Berlin-Dahlem

  32. Fermi takes his Nobel and does not go home

    Stockholm Concert Hall

  33. The discovery of fission

    1 month, 26 days

  34. Hahn writes to Meitner: it is barium

    Kaiser Wilhelm Institute for Chemistry, Thielallee 63, Berlin-Dahlem

  35. Meitner and Frisch in the snow at Kungälv

    Kungälv, near Gothenburg

  36. Frisch sees the fragments

    Institute for Theoretical Physics, Blegdamsvej 17, Copenhagen

  37. Bohr announces fission in Washington

    George Washington University, Washington

  38. Meitner and Frisch explain fission in Nature

  39. The Uranverein

    ≈ 5 years, 11 months

  40. Einstein signs Szilárd’s letter

    Nassau Point, Peconic, Long Island

  41. Bohr and Wheeler: it is uranium-235

  42. Sachs brings the letter to Roosevelt

    The White House, Washington

  43. The Frisch–Peierls memorandum

    Poynting Physics Building, University of Birmingham

  44. Seaborg’s group identifies plutonium

    Gilman Hall, University of California, Berkeley

  45. Japan’s Ni-Go project

    ≈ 4 years · Riken, Komagome, Tokyo

  46. The MAUD Report

  47. Heisenberg visits Bohr in occupied Copenhagen

    Copenhagen

  48. Heisenberg briefs Speer

    Harnack House, Berlin-Dahlem

  49. The Manhattan Project

    ≈ 3 years

  50. The heavy-water raids

    ≈ 1 year, 4 months · Vemork hydroelectric plant, near Rjukan

  51. Groves and Oppenheimer choose Los Alamos

    Los Alamos Ranch School, New Mexico

  52. Operation Freshman fails

  53. The first chain reaction

    6 hours, 8 minutes · Squash court under the west stands of Stagg Field, University of Chicago

  54. A safety rod trips, and Fermi calls lunch

    Squash court under the west stands of Stagg Field, University of Chicago

  55. Chicago Pile-1 goes critical

    Squash court under the west stands of Stagg Field, University of Chicago

  56. Gunnerside wrecks the heavy-water cells

    Vemork hydroelectric plant, near Rjukan

  57. Serber’s Los Alamos Primer

    Los Alamos Ranch School, New Mexico

  58. Bohr escapes occupied Denmark

  59. The X-10 reactor goes critical

    X-10 Graphite Reactor, Oak Ridge, Tennessee

  60. Y-12’s calutrons start up

    Y-12 plant, Oak Ridge, Tennessee

  61. American bombers hit Vemork

    Vemork hydroelectric plant, near Rjukan

  62. The ferry Hydro is sunk

    Lake Tinnsjø

  63. Chien-Shiung Wu joins the project

    Columbia University, New York

  64. Plutonium-240 kills the Thin Man

  65. Hanford’s B Reactor goes critical, then dies

    B Reactor, Hanford, Washington

  66. The Haigerloch reactor falls short

    Rock cellar under the Castle Church, Haigerloch

  67. The plutonium core is assembled

    McDonald ranch house, Trinity site

  68. The Gadget is hoisted up the tower

    Trinity ground zero, Jornada del Muerto, New Mexico

  69. Countdown at Trinity

    19 minutes, 15 seconds · S-10000 control bunker, Trinity site

  70. The automatic timer takes over

    S-10000 control bunker, Trinity site

  71. Trinity

    Trinity ground zero, Jornada del Muerto, New Mexico

  72. Fermi drops scraps of paper

    Base Camp, Trinity site

  73. Hiroshima

    Hypocentre over Shima Hospital, Hiroshima

  74. Farm Hall hears the news

    Farm Hall, Godmanchester

  75. Nishina surveys Hiroshima

    Hypocentre over Shima Hospital, Hiroshima

  76. Nagasaki

    Hypocentre over Matsuyama-machi, Nagasaki