Drunkard's Walk - Leonard Mlodinow [101]
IN THE FALL OF 1941, a few months before the Japanese attack on Pearl Harbor, an agent in Tokyo sent a spy in Honolulu an alarming request.4 The request was intercepted and sent to the Office of Naval Intelligence. It wended its way through the bureaucracy, reaching Washington in decoded and translated form on October 9. The message requested the Japanese agent in Honolulu to divide Pearl Harbor into five areas and to make reports on ships in the harbor with reference to those areas. Of special interest were battleships, destroyers, and aircraft carriers, as well as information regarding the anchoring of more than one ship at a single dock. Some weeks later another curious incident occurred: U.S. monitors lost track of radio communications from all known carriers in the first and second Japanese fleets, losing with it all knowledge of their whereabouts. Then in early December the Combat Intelligence Unit of the Fourteenth Naval District in Hawaii reported that the Japanese had changed their call signs for the second time in a month. Call signs, such as WCBS or KNPR, are designations identifying the source of a radio transmission. In wartime they reveal the identity of a source not only to friend but also to foe, so they are periodically altered. The Japanese had a habit of changing them every six months or more. To change them twice in thirty days was considered a “step in preparing for active operations on a large scale.” The change made identification of the whereabouts of Japanese carriers and submarines in the ensuing days difficult, further confusing the issue of the radio silence.
Two days later messages sent to Japanese diplomatic and consular posts at Hong Kong, Singapore, Batavia, Manila, Washington, and London were intercepted and decoded. They called for the diplomats to destroy most of their codes and ciphers immediately and to burn all other important confidential and secret documents. Around that time the FBI also intercepted a telephone call from a cook at the Japanese consulate in Hawaii to someone in Honolulu reporting in great excitement that the officials there were burning all major documents. The assistant head of the main unit of army intelligence, Lieutenant Colonel George W. Bicknell, brought one of the intercepted messages to his boss as he was preparing to go to dinner with the head of the army’s Hawaiian Department. It was late afternoon on Saturday, December 6, the day before the attack. Bicknell’s higher-up took five minutes to consider the message, then dismissed it and went to eat. With events so foreboding when considered in hindsight, why hadn’t anyone privy to this information seen the attack coming?
In any complex string of events in which each event unfolds with some element of uncertainty, there is a fundamental asymmetry between past and future. This asymmetry has been the subject of scientific study ever since Boltzmann made his statistical analysis of the molecular processes responsible for the properties of fluids (see chapter 8). Imagine, for example, a dye molecule floating in a glass of water. The molecule will, like one of Brown’s granules, follow a drunkard’s walk. But even that aimless movement makes progress in some direction. If you wait three hours, for example, the molecule will typically have traveled about an inch from where it started. Suppose that at some point the molecule moves to a position of significance and so finally attracts our attention. As many did after Pearl Harbor, we might look for the reason why that unexpected event occurred. Now suppose we dig into the molecule’s past. Suppose, in fact, we trace the record of all its collisions. We will indeed discover how first this bump from a water molecule and then that one propelled the dye molecule on its zigzag path from there to here. In hindsight, in