Atomic Heritage

Today marks the 70th anniversary of the U.S. dropping an atomic bomb, the so-called "Little Boy," on the Japanese city of Hiroshima. The city was instantly leveled, and tens of thousands of Japanese civilians were killed.

After the crew of the Enola Gay confirmed it had dropped the bomb to General Leslie Groves, the military head of The Manhattan Project, Groves called J. Robert Oppenheimer, the so-called "Father of the Atomic Bomb," to offer his hearty congratulations and discuss future plans. The call was recorded and transcribed.


According to Alex Wellerstein, a professor at the Stevens Institute of Technology, the missing parts of the conversation touch on "secrecy and the Smyth Report," a running-historical account of the Manhattan Project.


Some notes on their conversation:

—Both men wanted to drop Little Boy at night, presumably to maximize the number of casualties  and ensure a good view was available for research purposes.


—Oppenheimer expressed his doubts about the endeavor as a whole and it's a wonder if this conversation, and his doubts, were used against him when the decision was made to strip him of his security clearance at the Atomic Energy Commission nine years later.

—Groves mentions "the next objective" which makes it clear, if it wasn't already, that the plan always was to drop the second bomb, Fat Boy, on Nagasaki.


—Groves closes with mention of an "effort" that "will be devoted to the [objective] beyond that." This is likely referencing the development of the much-more-powerful hydrogen bomb, but Wellerstein thinks it refers to plans to drop a third (as-yet-unmade bomb) on another Japanese city.

This phone call was made and completed within minutes, when the cloud over Hiroshima had not even begun to dissipate. In the air, the U.S. bomber began to fly back to base.  On the ground, thousands had already been vaporized.


[h/t nuclear historian and Twitter user Alex Wellerstein]

David Matthews operates the Wayback Machine on—hop on. Got a tip? Email him: