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Einstein’s Ordnance

Spring 1998 | Volume 13 |  Issue 4

KEYPORT, WASH.: In preparing this issue’s article on World War II torpedoes, we received invaluable help from the Naval Undersea Museum, which documents and preserves the history of submarines, torpedoes, mines, and related technologies. Among its holdings the museum has copies of wartime correspondence between Albert Einstein and the Navy’s Bureau of Ordnance (BuOrd) on ways to improve torpedo design and performance. The letters (whose originals are in the National Archives) afford fascinating glimpses of how a longtime pacifist and theoretician applied his powerful mind to the practical business of building devices of destruction.

Wartime letters show how the titan of theoretical physics worked to improve the torpedoes used by the U.S. Navy

BuOrd’s Lt. Stephen Brunauer solicited Einstein’s help in May 1943. The next month Einstein came up with his first suggestion, a way to make a torpedo detonate just as it passed beneath a ship’s keel. In Einstein’s scheme a pair of electromagnetic coils at the front and rear of the torpedo would be connected in series with an electromagnet between them. The two coils would have opposite magnetic polarity, so when the torpedo was far from the target ship, the induced current between them would be zero for reasons of symmetry. As the torpedo approached the ship, the hull’s magnetic field would start to be felt. Since the field would be stronger at the front of the torpedo than at the rear, it would induce a current. Then when the torpedo passed beneath the keel, the fields from either side of the hull would cancel each other out, and the current would briefly dip to zero, setting off the detonator.

In August Einstein turned his attention to torpedoes detonated by contact rather than magnetic impulses. He explained why the explosive charge in such torpedoes should be placed at the front instead of the rear and suggested a protruding hollow tip, possibly armed with a projectile, to increase the likelihood of puncturing the hull instead of just shaking it. But contact detonation raised a new problem: The force of a violent collision with the hull could crush the head of the torpedo before detonation was completed.

In October Einstein suggested a possible way around this difficulty: Put the explosive in the rear of the torpedo and rotate it after impact to bring the business end closer. At first he thought the increased water speed right next to a ship’s moving hull would do the trick. Two months later, though, he decided that even if his idea could be made to work, the turning forces would destroy the torpedo. Once again he proposed adding a small empty space at the front. It would crumple before the rest of the head, buying a few extra thousandths of a second to give the explosive time to detonate properly. (Navy engineers eventually solved the problem by redesigning the contact detonator’s firing pin.)

Besides showing the thought processes of a genius at work, the letters reveal Einstein’s essential humanity just as effectively as the famous pictures of him sticking out his tongue and playing the violin. History’s greatest physicist can be seen expressing contempt for “snobbish people” in the military bureaucracy, struggling with the English language (“The metal container, mainly through his inertia, is …”), and like everyone else who writes a date in early January, mistakenly putting down the old year, crossing out the last digit, and increasing it by one.

Elsewhere the correspondence is reminiscent of the lecture a prominent physicist once gave at Brookhaven National Laboratory in which he recalled his train ride to a scholarly conference years before. Every few minutes the lecturer said something like “At the next stop Heisenberg [or Bohr or Schrödinger or whoever] got on, and he said… .” At the conclusion of the talk one member of the audience shook his head in mock disgust and said, “What a name-dropper!” Einstein achieves something of the same effect with offhand references to such luminaries as “my colleague Neumann” (John Von Neumann), “Gamov” (George Gamow, a rising star in nuclear physics), and Vannevar Bush.

Most of all, Einstein’s letters, filled with hasty sketches and rough calculations, show how easily he could set aside his relativity theory and discussions of God shooting dice to work on practical inventions. The old patent examiner knew how to analyze his devices for flaws and make them stand up to real-world conditions. As Thomas P. Hughes wrote in these pages in 1991, “Judging from his use of physical metaphors in his scientific writing, his preference for visual thinking, and his familiarity with inventions, it is safe to assume that he fully recognized the similarity between the intellectual activity of the creative scientist and that of the creative inventor… . For Einstein a hard-and-fast line between technology and science simply did not exist.” The Naval Undersea Museum can be reached at P.O. Box 408, Keyport, WA 98345.

More on Torpedoes

ON THE SHELF: Readers who want to know more about World War II torpedoes and submarine warfare will be interested in three recently published books. Hellions of the Deep: The Development of American Torpedoes in World War II , by Robert Cannon (Penn State Press, $28.50), is an exhaustive account based on copious oral histories and documentary sources. Amid vivid reminiscences from servicemen, engineers, and scientists, Gannon describes the problems, solutions, infighting, and bureaucratic inertia surrounding not only the Mark 14 but the electric Mark 18, the air-dropped Mark 24, and more than a dozen others that underwent development during the war.

A much more personal account comes from Adm. James F. Calvert, whose 1995 memoir Silent Running: My Years on a World War II Attack Submarine is now available in paperback from Wiley ($16.95). Calvert served on the Jack under Lt. Comdr. Tommy Dykers, and here is how he describes his sub’s first experience with the Mark 6 exploder: “We worked into an excellent position and fired three torpedoes—the Jack ’s first war shots of her career. Short of the predicted torpedo run time, we heard a tremendous explosion. That should finish him, I thought.

“‘ Damn those exploders … damn them all to hell! ’ said Dykers as he looked through the scope.

“‘The first torpedo prematured … just before it got to the MOT [middle of the target] … and I don’t know whether the other two passed under without exploding, or missed. Son of a bitch from Baghdad !’ came the bitter exclamation from the skipper.” (Despite continuing torpedo trouble, Jack ’s later forays were considerably more successful.)

Just published by Berkley Books is The Navy Times Book of Submarines: A Political, Social, and Military History ($31.95), which covers the entire history of submarines from the sixteenth century to the present. Like an aggressive attack-sub captain, Harris relentlessly searches out and destroys errors in other books, to the potential puzzlement of readers who have not heard of the errors or the books in question. Despite this sometimes truculent tone, as well as an unreliable index and the author’s unfortunate penchant for incomplete sentences (“Malfunction? Non-function.” “Design flaw? Several.”), The Navy Times Book of Submarines is a lively summary that both novices and experienced students of the field will find enlightening.

Scholars in the Sun

PASADENA, CALIF.: The Society for the History of Technology (SHOT) held its 1997 annual meeting in the sun-drenched city that is home to Caltech, the Jet Propulsion Laboratory, and the Mount Wilson Observatory. Despite all these attractions, the society had never before convened in Southern California. But last fall, inspired perhaps by Northwestern’s football team, which played in the 1996 Rose Bowl after an absence of 47 years, SHOT finally made its own overdue trip to Pasadena.

At a panel discussion on publishing, an academic-press editor reported dim prospects for technical monographs in book form. Where publishers could once count on selling at least a thousand copies of such studies, sales now typically total a few hundred, requiring high prices and an unreasonably large subsidy. In response, monographs with narrow appeal are increasingly being published electronically. (One audience member, who routinely pulls century-old books off the library shelf but struggles to recover five-year-old computer files, wondered how long the electronic versions would remain usable.) All the participants agreed that rigorous scholarship and vigorous marketing are both important in publishing, but they reached no definitive agreement on how, and how far, the two might be combined. Dava Sobel’s Longitude was cited to show how a serious historical work can still be a bestseller.

As usual, the assembled scholars used a variety of multimedia aids to illustrate their papers. Perhaps the most original prop appeared during a paper on gunpowder manufacture in eighteenth-century Sweden. After explaining how saltpeter was extracted from urine and feces, sometimes by boiling down dirt from stable floors, the presenter passed around a glass filled with saltpeter solution and invited the audience to taste it, as gunpowder producers once did to test for purity. His offer found few takers.

The Leonardo da Vinci Medal for contribution to the history of technology went to Ruth Schwartz Cowan of the State University of New York at Stony Brook. The Dexter Prize for outstanding books went to A Nation of Steel: The Making of Modern America, 1865-1925 , by Thomas J. Misa (Johns Hopkins University Press), and The Rocket and the Reich: Peenemunde and the Coming of the Ballistic Missile Era , by Michael J. Neufeld (Free Press).

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