Sunday, March 29, 2009

9/11 "Truthers" Meet their Waterloo - The Ron Craig Talk

The UW 9/11 Research Group, which previously sponsored two presentations by truthers, has finally gotten around to hearing the other side.

Ron Craig, a professor at Ryerson University with extensive training and experience in explosives, gave a talk Friday night in the Arts Lecture Hall at the University of Waterloo. Here's a brief summary:

He started by asking, "How many people here believe the WTC buildings were brought down by explosives?" Sadly, about half the people in the audience of approximately 100 raised their hands.

He then showed clips of the WTC buildings collapsing, some eyewitness testimony, and excerpts of last year's appalling presentations by A. K. Dewdney and Graeme MacQueen. He then asked rhetorically, "After seeing all this, how could you not believe the towers were brought down by explosives?"

Briefly, his answer was "expectation bias": investigators reach a premature conclusion without examining all the relevant data.

9/11 "Truthers" start with a presupposition, then look for data to support it. By contrast, real fire investigators start with documents such as NFPA 921, which outlines a scientific basis for investigating these incidents.

Craig pointed out that the WTC buildings used an innovative design for lightweight construction. They were the first super-high buildings to use this kind of construction, without heavy girders. The buildings weighed only 1/2 of what a conventional building would have weighed.

When demolition experts want to bring down a building, he said, they drill into columns and place the explosives. But no cement columns were used in the WTC. Furthermore, maintenance at the buildings reports that core beams above the 84th floor were inaccessible.

He then examined one claimed scenario for controlled demolition: in this scenario, explosives were placed on every floor. He then estimated how much explosive would be needed in this scenario, and came up with 1300 pounds of TNT-equivalent per floor, for a total of 143,000 pounds. Clearly this would be infeasible to set up without someone noticing.

Furthermore, such a large amount of explosive would have blown out windows in other buildings for blocks around. But this did not occur. In an explosive detonation, the typical inury is from flying glass, but there is no evidence that this occurred, nor evidence of other kinds of projectile injuries.

Explosives create heat of as much as 7000 degrees. Thermal injuries will be accompanied by primary blast injuries caused by pressure when the shockwave progesses through the body (e.g., middle ear injuries). "Blast lung" can occur at 50 to 150 psi. But not a single person in NY exhibited any symptoms of PBI.

Claims that thermite was used is undermined by the fact that no barium nitrate was found in the debris. He estimated that 61,000 pounds of thermite would have been needed. Again, it would have been impossible to set this up without someone noticing. Claims that sulfur was a signature of thermite/thermate are silly, because both the elevator shafts and stairwells were constructed with drywall, which is gypsum (calcium sulfate with 18% sulfur content).

Claims that molten steel was still flowing 21 days after the attacks are implausible. He showed one slide that supposedly depicted white-hot metal being observed by workers; it was actually just a worklight, as a video showed.

There is no good evidence that there were pools of molten steel. Many metals were at WTC, and low-temperature alloys could easily have formed. NFPA 921 says "if this occurs it is not an indication that accelerants were used or were present in the fire."

He then addressed the claim that "no other steel frame building has ever collapsed because of fire". He addressed other fires, such as this one at Delft. During the fire there was a partial collapse with "squibs" visible just as in the WTC.

He compared the WTC fire to other fires, such as the one in Madrid and One Meridian Plaza in Philadelphia. Both of these buildings had designs quite different from WTC.

Overall, I'd rate this part of the presentation as an A-. I think his points were very effective, although he could have also referenced the 1967 McCormick Center fire in Chicago, and he could have pointed to the lack of seismic evidence for explosions.

After the talk, there were some questions from the audience. One questioner asked him if he considered the "geo-political context" for 9/11. To his credit, Craig said that this was not his area of expertise; he is a fire and explosives expert, and his job is to look at the hard evidence, not speculations about motives.

Another questioner suggested that the Towers were brought down by some high-tech explosive invented by the government but unknown to everyone else. Craig found this suggestion (and a similar suggestion that "lasers" were used) ridiculous, saying that he regularly attends explosives conferences and such a thing could not be kept secret from experts.

Another questioner brought up the collapse of WTC 7. Craig said that he did not know for sure the cause of the collapse of that building, because not enough evidence was gathered yet. He said that he expects we will eventually know, because there is a strong motivation by architects, engineers, and insurance companies to understand the reasons behind the collapse, and many people are working on it.

I'd rate the question-answering portion as B+. Sometimes he simply reiterated previous points, instead of attempting to address the question from another angle, but overall he was generally effective.

Overall, I thought Ron Craig did a good job of demolishing the bizarre and unsupported claims by truthers that explosives brought down the World Trade Center buildings. Regrettably, it is unlikely to have much impact on truthers, who typically hold their beliefs with a religious fervor.

Friday, March 27, 2009

The Mother of All Rejection Letters

The Humanist Association of Canada Spring 1992 Newsletter contained the following item. Perhaps it is apocryphal, but it's funny even if not true.

"For writers only -- Every writer has received rejection slips; too many of them for most. The "Financial Times" has quoted the "mother of all rejection slips", translated from a Chinese economic journal. It goes like this:

We have read your manuscript with boundless delight. If we were to publish your paper, it would be impossible for us to publish any work of lower standard. And as it is unthinkable that in the next thousand years we shall see its equal, we are, to our regret, compelled to return your divine composition, and to beg you a thousand times to overlook our short sight and timidity."

Tuesday, March 17, 2009

A Conference I Won't Be Attending

Here is some conference spam I recently received:

Re: INVITATION for oral presentation at ICCE-17th Hawaii, USA

Upon review of your expertise in composite and nanotechnology of materials or physics/chemistry of materials/devices, and metals and concrete research, it gives me pleasure to invite you to orally present a paper at the coming 17th Annual International Conference on Composites or Nano Engineering, ICCE-17, July 26-31, 2009 in Hawaii, USA.. This is a truly “international” conference held in the USA, where the majority of the participants are from outside USA. The topic is broad to include almost all science and engineering, due to the emphasis of interdisciplinary research in nanotechnology.

The ICCE-17 Hawaii Call for Papers has received overwhelming responses of over 600 abstracts. The emphasis of the conference is to

(1) to learn the state of the art in hot topics where funding exists, such as Biomedical and Nano research on multifunctional materials and structures,

(2) provide a forum of exchange of ideas between Chemists, Physicists, Biologists, Engineers, mathematicians and mechanicians, to promote interdisciplinary approach to Nano/Biomedical/ Composites Technology,

(3) encourage participants to conduct interdisciplinary joint research and write joint research proposals

The venue hotel rate is being negotiated (prices falling due to recession), and the venue hotel and the island will be announced soon. The conference web is,

These ICCE-17 detailed abstracts will be reviewed and appear as short papers in World Journal of Engineering, upon payment of registration fee and attendance of ICCE-17. Further, “all” full length version of these short papers, with paper title change, will be reviewed and published in WJOE or in Composites B journal. Thus, all participants will have two journal papers as a benefit of coming to ICCE-17 Hawaii. Due to budgetary constraints, we are unable to offer financial assistance.

Looking forward to seeing you in Hawaii.

Yours sincerely,

David Hui, Ph.D.,
Chairman ICCE-17 Hawaii, USA
Professor of Mechanical Engineering Univ of New Orleans
Editor-in-Chief, Composites Part B:
Doctor Honoris Causa (Italy, Nov. 2008, Vietnam, Dec. 2006, Ukraine, Nov. 2004)

This invitation has many signs of bogosity:

1. It was sent to an old address I set up 15 years ago for a conference and have not used since, a clear sign the author has used some spam service.

2. It falsely claims that I have been invited because of my "expertise in composite and nanotechnology of materials or physics/chemistry of materials/devices, and metals and concrete research", all fields that I have never done any research in. Also note the wide variety of unrelated topics listed as the theme of the conference -- this is quite unusual for a legitimate conference.

3. It has random grammatical errors and punctuation inconsistencies, such as capitalizing "Chemists" but not capitalizing "mathematicians", and putting "all" in quotes.

4. The author lists his honorary doctorates.

Sorry, I won't be going to this conference.

Thursday, March 05, 2009

The Whininess Quotient

The Whininess Quotient (or WQ) of a class of students is defined to be the dimensionless quantity

(number of questions asked about how marks are assigned)
(number of questions asked about content of the course)

The WQ can be classified as follows:

WQ < 1/2: Your class really cares about the material! Congratulations!

1/2 ≤ WQ < 2: Caution: whiners are beginning to dominate the conversation.

2 ≤ WQ < &infin: It's going to be a long semester.

WQ = ∞: Time to look for another university.


German has several words for which there is no English equivalent, and so we've adopted them into our language. Of these, perhaps the most famous is Schadenfreude (literally, something like "harm-joy"), which means "pleasure taken at the misfortune of others".

Another good one is Ohrworm. Literally "ear worm", it refers to a catchy song that you just can't get out of your head.

My colleague Jean-Paul Allouche introduced me to another some time ago: Sprachgefühl. Literally, "language feeling", this word refers to a native speaker's intuitive understanding of the subtleties of his own language. When a French speaker says, "We now prove this by recurrence on n", Jean-Paul looks at me and mouths the word "Sprachgefühl", because he knows that the speaker should have said induction, not recurrence. Similarly, French speakers often say couple instead of pair, and speak about notations instead of notation. (Notation is usually a mass noun in English and hence rarely appears in the plural in mathematics and computer science research -- unless the paper is written by a non-native speaker!) French speakers also often say something like "We denote by |x| the length of the word x", when a native speaker would probably say something like "We let |x| denote the length of the word x".

Based on this, I've coined a new word: TeXgefühl. This means "the intuitive understanding of what is proper usage in the mathematical typesetting language TeX". (There is also the related word, LateXgefühl.) Neither word appears in a Google search, so I really do appear to be the first to say them online.

Both TeX and LaTeX have some subtleties which beginners find difficult to master. These include constructs that improve the appearance of the manuscript, like knowing to put "\ " after any lower-case letter followed by a period that does not end a sentence, as in "Dr.\ Smith"; if you don't do this, tex inserts too much space between "Dr." and "Smith". Another example of TeXgefühl is knowing to use the proper kind of dots in a mathematical expression -- you should write "x_1,   x_2,   \ldots,   x_n" but "x_1   x_2   \cdots   x_n". The subtleties also include knowing that both TeX and LaTeX have reasonably good algorithms for deciding on spacing, so that manuscripts should not be littered everywhere with "\noindent" and \bigskip", and that there is no need to put "\par" or "\\" at the end of every paragraph.

If you have LaTeXgefühl, you know not to hard-code references to theorems, lemmas, etc.. Instead, you use labels inside theorem environments to store the name of the theorem, and then you refer to to the theorem by saying something like Theorem~\ref{thm1}. (The twiddle after "Theorem" is another example of TeXGefühl.)

Those with TeXgefühl know that single-letter functions are always in the italic font, using something like $f(x)$, but that multi-letter functions, such as sin and cos, are nearly always in the roman font, and should be specified using the built-in expressions \sin and \cos. (For some reason, many people also forget this for \gcd.) They know that left-quotes in TeX are different from right-quotes, so that you should write ``quoted expression'' instead of "quoted expression". And they know that page ranges should be specified with two hyphens, like "237--246".

It's hard to attain Sprachgefühl in a foreign language - I will probably never get there in French or German. But with a little work, nearly everyone can attain it in TeX.