Daily Archives: December 20, 2007

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.

On Philately

[First published in GOTOXO as on December 20, 2007.]

Courtesy of Sam Ruby’s Planet Intertwingly I just came across a wonderful post by Rob Weir, A Lick Back in Time. Though Rob also works for IBM we have never met save via our blog postings. This is so far my favorite of his posts, for in it I learned that we are fellow stamp collectors, or philatelists.

Rob’s post is about the U.S. Commemorative stamps issued in 1957. I was an active collector in those years. I got an allowance of about $15 each week. My mother said I had to pay for my school lunches and do what I wished with what was left. As a result, since I was a passionate collector in those days, I ate very sparingly so I could save as much as possible for my weekly journey to the local stamp dealer in Albuquerque in those days, Mr. Flynn:
Stamps 1957
Cover Scott’s Catalog

Stamps 19574

I spent many wonderful Saturdays in his store, looking at many stamps and buying a few. My specialty was U.S. commemoratives, and I have a pretty complete collection from 1933 to about 1960. Here are a few photos I just took of my stamp collection. I hadn’t viewed some of these stamps for several decades:

Stamps 1957
First Day Covers circa 1957

Note the Polio Stamp. See Don’t forget to get your Flu Shot and the mention of Polio therein.

The Noah Webster Cover is also of interest, for it bears the postmark of Hartford, Connecticut. As it happens, I had a phone call yesterday with one of Connecticut’s leading proponents of the use of open-source and other open technologies in Connecticut schools. He lamented that while all of Connecticut’s school districts now have access to high-speed Internet courtesy of a statewide initiative, few schools have the resources and trained personnel to make proper use of the connection, and cited Hartford as a case in point.

Stamps 1957
Plate Blocks 1957

Stamps 1957
1957 Commemoratives, Page 1

Stamps 1957
1957 Commemoratives, Page 2

Stamps 1957
1957 Commemoratives, Page 3

Stamps 1957
1957 Plate Block of Oklahoma Stamp

Rob wonders in his post why the Oklahoma stamp has the symbol of the atom. My own guess is that this was a reflection of the peaceful uses of atomic power of the mid 1950’s, as a similar symbol can be found in Scott’s 1070, “Atoms For Peace,” 1955:

1957 Stamps
1955 Commemoratives

Note the similiarity of the atom in this stamp to that found in the Oklahoma stamp.

It is also worth noting the stamp honoring Andrew M. Mellon. The foundation named after him provided much of the key funding for the Sakai and Kuali open-source projects that were developed by, and are being used within, several of our major Research Universities.

My grandfather, Dr. E. Kyle Simpson, born in 1883, was also a philatelist. He saved many stamps during his years as a doctor in Pontiac, Michigan, in the 1930’s and later. He saved many full sheets, though since he started doing this only after 1933, they were of little monetary value, though a good deal of sentimental value. He sent them to me in the 1950’s when he learned I also was a stamp collector.

Grandfather's Stamp Collection1

Grandfather's Stamp Collection2

Grandfather's Stamp Collection3

I am posting this on my XO blog as there is a bit of the collector in all of us, and I would hope that one of the main uses of the XO in the years to come will be the cataloging of their culture by the members of the XO Generation

Laughable Links

Blogging can be fun. Not only is it fun to write posts, if you use WordPress to do your blogging you can learn how people reach your blog posts. Some of the incoming links can be quite surprising, and some are quite funny.

I just noted that a link to my post On the shortest Python program can be found at Affordable Life Insurance!

I have no idea what led to this link, though it does recall one my of favorite scenes in all of Woody Allen’s movies. In Take The Money And Run (1969), there are some memorable quotes. Here are a few featured in the IMDB article:

Bank Teller #1: Does this look like “gub” or “gun”?
Bank Teller #2: Gun. See? But what does “abt” mean?
Virgil: It’s “act”. A-C-T. Act natural. Please put fifty thousand dollars into this bag and act natural.
Bank Teller #1: Oh, I see. This is a holdup?

Virgil: Nobody wears beige to a bank robbery!

There is at least one missing from this list. It comes in my favorite scene, where the hero, the hapless bank robber Virgil is sentenced to three days in jail with a life insurance salesman. As the cell door slams shut we hear the immortal words:

Let’s talk term life insurance.

I expect the salesman wanted to tell Virgil that term insurance was the best because it was so affordable, and perhaps that explains why Affordable Life Insurance linked to the work of Blogger Dave.

I can think of a similar scene that I would love to see put to film. Titled “The OOXML War Against Reason,” the film would have a scene where a number of Microsoft senior executives and technologists are convicted of the high crime of Insane Reasoning and Utmost Stupidity In The Drafting Of A Standard, and are then sentenced to thirty days in a jail cell with Andy Updegrove, Bob Sutor and Rob Weir.

I have earlier written of the possibility of using recognized open-source experts to star in movies, in Who should be the Pirate of the Caribbean? Linus Torvalds? Johny Depp? Russell Crowe?, and hereby suggest that Brad Pitt should play the role of Rob Weir, reprising his performance as Achilles in Troy, for Rob has specialized in exposing the Achilles heel of the OOXML standard, faulty reasoning.

IMDB’s list of quotes from Take The Money And Run includes another that is especially apropos to the topic of my recent post Technorati Considered Harmful:

Louise: He is always very depressed. I think that if he’d been a successful criminal, he would have felt better. You know, he never made the ‘ten most wanted’ list. It’s very unfair voting; it’s who you know.

Alan Turing’s Definition of a Computing Machine

[First published in GOTOXO as Python-XO: Alan Turing’s Definition of a Computing Machine on December 20, 2007.]

In a previous post in this series about the Python programming language and the XO laptop, XO-Python: On Von Neumann’s First Program, I made mention of the work of John von Neumann in 1945 in which he wrote one of the first known programs in a form close to that used in today’s programming languages.

In this post we look at the work of another of the greatest mathematicians of the twentieth century, Alan M. Turing. One of the fundamental papers in the history of mathematics and computing is Turing’s ON COMPUTABLE NUMBERS, WITH AN APPLICATION TO THE ENTSCHEIDUNGSPROBLEM, published in 1936.

Turing asked himself the question, “What does it mean to compute something,” especially in a mathematical sense. Towards that end he defined the notion of a “computing machine” as follows (with my emphasis added in bold):

We have said that the computable numbers are those whose decimals are calculable by finite means. This requires rather more explicit definition. No real attempt will be made to justify the definitions given until we reach §9. For the present I shall only say that the justification lies in the fact that the human memory is necessarily limited.

We may compare a man in the process of computing a real number to a machine which is only capable of a finite number of conditions q1, q2, …, qR which will be called “m-configurations”. The machine is supplied with a “tape”, (the analogue of paper) running through it, and divided into sections (called “squares”) each capable of bearing a “symbol”. At any moment there is just one square, say the r-th, bearing the symbol S(r) which is “in the machine”. We may call this square the “scanned square”. The symbol on the scanned square may be called the “scanned symbol”. The “scanned symbol” is the only one of which the machine is, so to speak, “directly aware”. However, by altering its m-configuration the machine can effectively remember some of the symbols which it has “seen” (scanned) previously. The possible behaviour of the machine at any moment is determined by the m-configuration qn and the scanned symbol S(r). This pair qn, S(r) will be called the “configuration”: thus the configuration determines the possible behaviour of the machine. In some of the configurations in which the scanned square is blank (i.e. bears no symbol) the machine writes down a new symbol on the scanned square: in other configurations it erases the scanned symbol. The machine may also change the square which is being scanned, but only by shifting it one place to right or left. In addition to any of these operations the m-configuration may be changed. Some of the symbols written down {232} will form the sequence of figures which is the decimal of the real number which is being computed. The others are just rough notes to “assist the memory”. It will only be these rough notes which will be liable to erasure.

It is my contention that these operations include all those which are used in the computation of a number. The defence of this contention will be easier when the theory of the machines is familiar to the reader. In the next section I therefore proceed with the development of the theory and assume that it is understood what is meant by “machine”, “tape”, “scanned”, etc.

Turing went on to prove some of the major results in mathematics in the last century. By defining in abstract form a “computing machine” he was able to characterize the kinds of things that could be computed by this machine. He then proved there were some things that could not be computed by this kind of machine, and in doing so he demonstrated there were fundamental limits to what could be computed. While these computers were universal in power, they were not universal in reach. There were, and are, some questions that cannot be answered by any computer, no matter how powerful.

Moreover, while his machine was abstract, all the computers we use today — the creation of scientists and engineers — are but practical instances of this abstract computing machine. Our real computers can compute everything that can be computed by what is known as “Turing’s machine,” and they can compute nothing that cannot be computed by Turing’s machine. For example, the XO can compute anything a desktop can compute. It may take longer, much longer, yet the XO has, at a fundamental level, the same power to unlock the secrets of the universe as does the desktop, or the world’s largest supercomputer.

All computers are fundamentally equivalent. Some are smaller, others are bigger. Some are faster, others are slower. Yet all do the same thing. It is a matter of degree, not a qualitative difference.

I wrote in a previous post, Python-XO: The Farmer in the Dell that programming is just a form of writing. The key point I wish to make here , especially in understanding the importance of Turing’s ideas to the nature of programming itself, is that computing itself is but a combination of reading and writing. This is why I emphasized “scanned symbol,” for this is the reading part. The writing part can be found in “writes down a new symbol” and “liable to erasure.”

Computing is a form of writing, as is a shopping list, a novel, or a computer program written in Python that instructs the computer how to do its reading and writing.

  • Pages

  • December 2007
    M T W T F S S
    « Nov   Jan »
  • RSS The Wayward Word Press

  • Recent Comments

    Sahana’s Respo… on A brief history of Sahana by S…
    Sahana’s Respo… on A brief history of Sahana by S…
    James Murray on On being the maintainer, sole…
    James Murray on On being the maintainer, sole…
    mrrdev on On being the maintainer, sole…
  • Archives

  • Blog Stats

  • Top Posts

  • Top Rated

  • Recent Posts

  • Archives

  • Top Rated