Shock Block: On the power of a single individual and the power of computer simulation

[First published in GOTO XO as Shock Block: On the power of a single individual and the power of computer simulation on December 20, 2007.]

Here is a photo of a unique object, my Shock Block:

Shock Block
Shock Block

Here is how the Shock Block came to be.

First a block of very hard clear plastic was machined to be a rectangular block to an accuracy of a few thousandths of an inch. Then a small hole was drilled through the center and a wire was run through the hole. The ends of the wire were then attached to a bank of capacitors that filled a room about fifteen feet long, ten feet wide, and perhaps ten feet high.

A switch was then thrown so that the entire charge stored in those capacitors was fed into the wire. The wire instantly vaporized and the effects of the resulting shock wave can be seen in the photo.

During my college summers in 1962-1966 I worked in the Air Force Weapons Lab (AFWL) in Kirtland Air Force Base in my hometown, Albuquerque, New Mexico. I got the job because I was an Explorer Scout in a troop that meet at the base during my high school years. It was there I first used a computer, and I still have the computer manual to show it, as I have described in an earlier post, Back In The Day: Computing in 1959, 1971. One of the scoutmasters worked at the personel office in the base, and with his help I was able to secure the job.

The main mission of AFWL in those days was to simulate the effects of nuclear and thermonuclear explosions in the atmosphere. This was due to the efforts the 1960’s of President John F. Kennedy’s his science advisor, Prof. Jerome Wiesner, to end nuclear testing in the atmmosphere. [1]
See for example, The Road Less Traveled and JBW: Foreward. The latter reference is particularly interesting in that I learned on reading it that Prof. Wiesner played a key role in founding MIT’s Media Lab, the creator in part of the XO Laptop:

At the time of my visit, Jerry was still weak from surgery and I did not want to tire him, but I had one other pressing question: Would he continue his efforts to realize a media laboratory at MIT? He responded that sometimes you get into something so far that you cannot pull out.

I worked at AFWL after the ratification of the Nuclear Test Ban Treaty, which confined testing to underground explosions. As a result the mission of AFWL included both underground tests, conducted at Yucca Flats in Nevada, and various simulations. I was not involved in any actual tests at Yucca Flats, though I did gain some education in office politics. One of the officers was deemed a bit of a pest, as was confirmed when I learned he had been given his own A-bomb to explode at Yucca Flats, as this would remove him from our presence for at least six weeks.

AFWL thus had a nearly unlimited budget to construct various Rube Goldberg devices to simulate the effects of nuclear explosions in the atmosphere. The Shock Block is one example. During my first summer at the lab I spent much of my working day in a Farday Cage, a room about twelve feet on a side encased in copper sheeting. I took thousands of pictures of oscilloscope traces as we vaporized various materials. The main form was to machine a similar block of plastic, insert a thin sheet of foil on top, and then cover the foil with a thinner piece of hard plastic with a square cut out in the middle. My area of expertise became the mixing of epoxy and its used to attach the thinner piece to the larger block. The capacitors were then charged up. When they were discharged the resulting current vaporized the foil, sending a small slice of material up to impact on the same material used in warheads. The scope pictures measured the effect of the resulting shock on the warhead material.

Within a few years we moved on to the use of computers. Again, cost was no object. As described in the “Back in the Day” post cited earlier, I wrote code for the CDC 6600 at NYU’s Courant Institute of Mathematical Sciences (CIMS) starting in the fall of 1966. That machine was serial number 2. A few months earlier I had written and run code on the CDC 6600 at AFWL. It was serial number 1, as the Air Force had first dibs in acquiring what was then the world’s premier supercomputer. Save employees of the maker, Control Data Corporation, I’m quite certain I am the only person to hav ever used both these machines, since you had to work at AFWL , have some programming skills, and have a Secret clearance to make use of S/N 1.

My programming efforts in the summer of 1966 were primarily done to determine the number of lead bricks that should be placed as shielding around what was then probably the most intense man-made source of X-rays on the planet. There was an immense device that could saturate a space of about a cubic meter with an intense burst of X-rays for the purpose of determining their effects on a nose cone and the electronics contained inside it. Though I can’t say I did the best possible job, I can assert I did an acceptable one, at least on a personal basis, for I am a father.

This is one of the great powers of the computer. It can be used to simulate things. As I have described in a previous post, Python-XO: Alan Turing’s Definition of a Computing Machine are computers are fundamentally alike. In particular, you can use one to simulate another. For example, you can use an XO to simlate the computer chip that can be found within a cell phone. You can also user a supercomputer such as IBM’s BlueGene to simulate the ways proteins fold. That is why IBM built it, though of course it can be used for other purposes.

It will be interesting indeed to witness the ways in which the XO will be used for simulation. All it will take is some imagination and some innovation.

It will also require providing education on how to do this. This is the main reason I write this blog.


1. Prof. Wiesner’s son Steve was a fellow resident of Paige House at Caltech for part of my undergraduate days.


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