EINSTEIN PRESSES ROOSEVELT ON ATOMIC RESEARCH

Peconic, Long Island, New York  August 2, 1939

On this date in 1939, one month before the outbreak of World War II in Europe, distin­guished German-born profes­sor, mathe­ma­tician, and physi­cist Albert Ein­stein wrote Presi­dent Franklin D. Roose­velt about the possi­bility of using a nuclear chain reaction to pro­duce enor­mous amounts of energy that could be used in making a bomb. German scien­tists, he noted in closing his letter, were busy researching just that possi­bility, having formed a Uran­verein (Ura­nium Club) earlier in April as part of their coun­try’s clan­des­tine efforts to develop and produce nuclear wea­pons of war. Not five months earlier, in Decem­ber 1938, German phys­i­cists stunned Ein­stein and other scien­tists who had escaped Nazi-occupied Europe by announcing they had split the ura­nium atom, a process later des­ig­nated nuclear fission. Roose­velt did not receive Ein­stein’s confi­dential hand-de­liv­ered letter until Octo­ber 11, but when he did he acted on it quickly, appointing a com­mit­tee, the S‑1 Ura­nium Com­mittee, to direct U.S. nuclear research starting with a $6,000 outlay.

In December 1942 Italian-born Enrico Fermi, who had patented the idea of a nuclear reactor in 1933, and Hun­garian-born Leó Szi­lárd—col­leagues whom Ein­stein had men­tioned in his letter to Roose­velt—went on to create the first atomic chain reaction at the Uni­ver­sity of Chi­cago and became mem­bers of the Man­hat­tan Engi­neering Dis­trict, the cover name for America’s atomic bomb pro­gram that evolved out of the S‑1 Com­mit­tee. (The project’s cover name derived from the then concen­tra­tion of nuclear energy exper­tise in Man­hattan, a New York City borough.) Leading the civil­ian scien­tific side of the project was a young 38‑year-old Amer­i­can theo­ret­ical physi­cist, J. Robert Oppen­heimer. Over­seeing the nearly $2 billion project (over $29 bil­lion in 2021 dollars adjusted for infla­tion) was the Man­hattan Pro­ject’s mili­tary direc­tor and West Point grad­u­ate Brig. Gen. Leslie Groves, who had overseen the construction of the Pentagon.

Apart from the initial July 16, 1945, deto­na­tion of a nuclear (pluto­nium) bomb nick­named “Gadget” at the top of a 100‑ft tower in the New Mexico desert, Man­hat­tan Pro­ject’s deploy­able nuclear wea­pons were “Little Boy” (ura­nium bomb) and “Fat Man” (plu­to­nium bomb). (Szi­lárd and 154 nuclear scien­tists lost the moral argu­ment at the highest levels of the new Truman admin­is­tra­tion to invite Japa­nese and inter­national obser­vers to view a second non­combat nuclear deto­na­tion, which they believed would have induced Japan’s leaders to sur­render uncon­di­tion­ally and thus spare lives. The weight of opin­ion was on the side of those who saw power­ful stra­tegic and prac­ti­cal bene­fits from using the bomb and ruled out a pre­view and warnings that the bomb was coming.)

Initially six Japanese cities were identi­fied as can­di­dates for nuclear incin­er­ation. The list was later reduced to four: Hiro­shima on south­ern Hon­shū Island, the largest of the Japa­nese Home Islands; Kokura (Hiro­shima’s back­up) and Naga­saki (Kokura’s backup) on Kyūshū, the southern­most Home Island; and Nii­gata on north­ern Hon­shū. Weather that per­mitted visual bombing settled Hiro­shima’s terri­ble fate; clouds and smoke over Kokura from an earlier U.S. fire­bombing of Yawata (Yahata), less than 5 miles away, settled that of Naga­saki. On August 15, six days after Naga­saki and tens of thou­sands of deaths later, Emperor Hiro­hito (post­humously referred to as Emperor Shōwa) announced his country’s uncon­di­tional sur­render to the Allies. The Japanese Instrument of Surrender, signed on Septem­ber 2, 1945, aboard the U.S. battleship Missouri at anchor in Tokyo Bay, officially ended World War II.



Trinity Site, New Mexico, 1945: Detonating the First Nuclear Bomb

Manhattan Project: Trinity site test tower, New Mexico, July 1945Manhattan Project: Explosives being readied for hoisting, Trinity site test tower, New Mexico, July 1945

Left: The 100-ft-tall steel tower constructed at a small Army air­field for the Trinity test. Inspired by the “three-person’d God” in a sonnet written by English poet and cleric John Donne, Trinity was the code­name chosen by Oppen­heimer for the desert site where the world’s first deto­na­tion of a nuclear device occurred, this on July 16, 1945, a date usually con­sidered to be the beginning of the Atomic Age. Trinity was located on the Alamo­gordo Bombing and Gun­nery Range (now part of the White Sands Missile Range) in a par­tic­u­larly dry stretch of southern New Mexico desert called the Jornada del Muerto—Spanish for “Jour­ney of the Dead Man.” Trinity lay 200 miles south of Los Alamos, where the atomic bombs were designed and built.

Right: The explosives of the 5-ton “Gadget” were carefully hoisted to the cor­ru­gated-steel shelter at the top of the tower for final assembly in mid‑July 1945.

Manhattan Project: Bomb assembly group leader, Trinity site, New Mexico, July 15, 1945Manhattan Project: Trinity test mushroom, New Mexico, July 16, 1945

Left: Norris Bradbury, bomb assembly group leader, stands next to the partially assembled “Gadget” atop the test tower, July 15, 1945. Among other things, Brad­bury had to ensure that the series of deto­na­tors needed to set off a nuclear chain reaction inside “Gadget” fired simul­ta­neously within a fraction of a millionth of a second.

Right: Trinity was a test of an implosion-design plutonium device, the same con­ceptual design used in the second nuclear device dropped on Japan, “Fat Man,” which was deto­na­ted over Naga­saki, Japan, on August 9, 1945. This photo was taken at 5:30 a.m., a 0.016 second after test deto­na­tion. The searing light of the explo­sion was more intense than any­thing ever wit­nessed before and could have been seen from space. Its core tem­per­a­ture was four times greater than that at the sun’s core. The awe­some roar of the air blast 30 seconds later “warned of dooms­day,” reported one witness. Oppen­heimer later remarked that the deto­na­tion reminded him of a pas­sage from the second-century BCE Hindu Bhagavad Gita: “Now I am become Death, the destroyer of worlds.”

Manhattan Project: Aerial view of ground zero, New MexicoManhattan Project: Oppenheimer and Groves at Trinity ground zero, New Mexico

Left: An aerial photograph of the Trinity crater shortly after the test. The nuclear device exploded with an energy equi­va­lent to around 20 kilo­tons of TNT and left a crater of radio­active glass 10 ft deep and 1,100 ft wide. Nothing remained of the 100‑ft-tall steel tower. The shock wave was felt over 100 miles away, and the mush­room cloud reached 7.5 miles in height. U.S. Presi­dent Harry S. Truman was posi­tively giddy with new con­fid­ence on a swift victory in the four-year Pacific War. From the Big Three victors’ con­fer­ence in Potsdam near the former Nazi capital, Berlin, Truman wrote his wife in mid-July 1945: “We’ll end the war a year sooner now, and think of the kids who won’t be killed.”

Right: J. Robert Oppenheimer (center, in dark suit and light-colored hat), Brig. Gen. Leslie Groves (in khaki uni­form to Oppen­heimer’s left), and other scien­tists and mili­tary person­nel inspect the melted remains of the test tower at ground zero after the Trinity blast. The photo was taken in Septem­ber when some parti­ci­pants returned for news reporters. Note men wearing shoe covers to keep from picking up radi­a­tion. The test site was littered with lop­sided marbles and knobbly sheets that later became known as Trini­tite. Trini­tite was primarily quartz and feld­spar, tinted sea green with min­erals in the desert sand, with droplets of condensed plutonium sealed into it.

University of California Television: The Manhattan Project