The Manhattan Project

Marvin Wilkening's Interview (1986)

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Wilkening, a physicist, traveled the Grand Circuit of the Manhattan Project, pursuing his specialty of measuring neutron intensity. He was at the first chain reaction in Chicago, then moved to Oak Ridge, next to Hanford, Los Alamos, and Trinity. Before the Army restricted visitors, he regularly took his New Mexico Tech physics students on field trips to Trinity. In this interview, Wilkening describes his experience of the Trinity test.
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[Interviewed by S. L. Sanger, from Working on the Bomb: An Oral History of WWII Hanford, Portland State University, 1995]

So there we were the night before the test, in one of those little huts, with thunder and lightning and the promise of a storm. Fermi called us together in a corner and told us no major problems were anticipated, but it's always pos­sible we have not calculated right. The winds may bring some fission products over us, he told us. They were prepared to evacuate us. I was at base camp, about nine miles south of Point Zero. It was scheduled to go at 4:30 a.m. but was postponed for an hour subject to further delay, because of the storm.

There was a countdown by Sam Allison, the first time in my life I ever heard anyone count backwards. We used welder's glass in front of our eyes, and covered all our skin. My feet were toward Mockingbird Gap, Point Zero was to my left. The countdown ended, and it was like being close to an old-fashioned photo flashbulb. If you were close enough you could feel warmth because of the intense light, and the light from the explosion scattering from the mountains and the clouds was intense enough to feel.

Immediately we turned around, and looked toward the blast, and the cloud was a white spot through the welder's glass. Terrific as it was, the blast was an anti-climax compared to the feel of the flash of light which traveled so much faster than the sound wave. We heard it, too far away to be like a close light­ning stroke, but that kind of phenomenon. We followed the fireball as it rose, white, then light orange. What was fantastic to me was the development of what, under other circumstances, would have been a beautiful purple color that was the result of the intense radiation from this ball of fire. Radiation interacting with air molecules. We had seen it in a laboratory, but here it was on a massive scale. That was the clue to the intensity of the radiation that was present. And we were almost 10 miles away. Yeah, okay, that was a signal that spoke volumes. It went, it worked. That purple light, and we were so far away.

Fermi was close by, he was dropping little pieces of paper into the blast wave to measure the explosive power. I didn't notice a lot of what was going on because we all had a job to do and it was up to you to do it. But Allison was there, and Oppenheimer and General Groves. I tuned in on Fermi; I had a tremendous admiration for him.

What do I think of the bomb, the rightness and wrongness? The thing that I can remember that was pretty deep in our minds was that our friends, some of them, were killed in the war, including a very close friend of mine from college killed in Europe. We had considerable concern. Suppose the Nazis had succeeded, maybe not in making a bomb, we didn't know that was possible either earlier. But suppose they had a reactor device that could sow the beaches with high-intensity fission products? Any reasonable person had to deal with it in a rational framework, and, well, you can't always win them all. Wars, that is.

We thought whatever it is, this atomic energy was a thing that had to be worked on. As far as the actual use, I think it was regrettable, but it had to be done. When it was announced, in August, Hiroshima and Nagasaki, the thing was, well, we had participated. But we felt if it hadn't been us, it would have been someone else.