Imagine it's July 1945 at the research laboratory in Los Alamos, New Mexico.

You're one of the country's foremost experts on explosives and you're standing in a darkened room.

You and your assistant are carefully studying a row of x-rays illuminated on a wall in front of

you.

The images show a 100-pound black hexagon made of plastic explosives.

Your assistant points to one spot on the images.

Right there.

God, another air bubble, and there, and there.

You exhale trying to stay calm.

Why does this keep happening?

For almost two years, you've been working here at Los Alamos,

leading the development of the materials that will be used to

trigger an atomic chain reaction in the first plutonium bomb. But lately things have not been going

well. Your assistant turns on the lights.

I don't know.

You really think these air bubbles are going to make that much of a difference, though?

It's hard to say, but we can't afford to take any risks.

The black hexagon in the x-rays is an explosive lens. 32 of these lenses will be assembled together

like a puzzle to create a sphere surrounding a core plutonium the size of an orange.

But casting the plastic explosives into these custom shapes has proven to be a major

challenge. You turn to your assistant. Now look, the chain reaction will only be triggered

if the pressure coming in on the plutonium core is

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