The Second Version

09/01/07

Right-wing Conspiracy Theories

LGF reports a story concerning a suspicious package at Miami port, which after turning positive in field tests for C4 was finally found to be innocuos.

The level of detail of the news story is too low to make an informed judgement, but I have an idea of what may have happened - and of why innocuous items may result positive for explosives.

The sensors used for field tests are simple devices (often, a sort of mass spectrometer called ion mobility spectrometer) compared to laboratory analytical instruments, built to detect one class of compounds - in this case, explosives. What most explosives (TNT, RDX, HMX) have in common is the presence of nitro groups, which I expect to be the main feature of the IMS signature of explosives. However, nitro groups are also contained in other molecules: dyes, certain solvents and drugs. It is also conceivable that compounds like amines, amides and urethanes (that is, common plastics) may give IMS signatures similar to explosives. Also fertilizers contain high amounts of nitrogen, often as nitrates an ureas (which are not nitro groups, but somewhat close). I'm available to conduct an experimental campaign to clarify these issues, if I can find a sponsor...

There is also the selectivity problem: high selectivity is already difficult to achieve with laboratory instuments; field instruments cannot go very far. This means that they aren't very good at discriminating between different chemicals especially within the same class.

As a matter of design bias, I'd prefer my explosive detector to give more false positives than false negatives, because a false positive is a pain in the back, but a false negative can cost many lives.

The story says that the suspect package in fact contained "sprinkler parts", which is another exercise in vagueness. But if these sprinklers became contaminated with some chemical - in the case of agricultural sprinklers, fertilizers - they may result positive for explosives. An investigation should be launched anyway, at least to find who caused that mess by leaving a suspicious package around.

But instead of acting rationally and fact-checking, a lot of LGFers don the tinfoil hat:
Prysorra 1/8/2007 05:46PM PST
*I answer my own question...
Either:
a. False positive for political pressure
b. Security coverup for political reason.
c. They misread their instruments.
C is not likely.

BabbaZee 1/9/2007 05:36AM PST
I seriously doubt they will EVER tell us the truth on these matters until something actually detonates. Everything that is stopped in time will be reported as "false alarms"
And yes, these are only two comments out of 260+, but most of the few on-topic comments have a similar tone. Only a handful of commenters tried to understand what may have actually happened, and apparently none even did a quick search for the principles of explosive detection.

Whenever a false alarm occurs, at LGF it's always like this - many don't even admit the existence of false alarms; there must always be evil, scheming jihadis somewhere and governmental cover-ups to keep the sheeple blissfully unaware. Sounds familiar? It should; it's the same basis of all conspiracy theories. Change a few words, and you'll get Loose Change 911. (Sligthly edited on 10/01)

Etichette: , ,

3 Commenti:

  • Fuckin' A.

    Di Blogger Wellington, Alle 10/1/07 14:19  

  • Aw sweet, my first quote! I'm famous.

    In any case, beware of your own assumptions. If shadow every shadow makes you no safer, then neither does ignoring every shadow keep you sane.

    Doubt is a weapon. Use it wisely.

    .....
    Note that the false positive was obtained *after* suspicious behavior. I refuse to believe that Middle Eastern men are all idiots and inherent prone to such foulups, and frankly I find the notion racist.

    Di Anonymous Prysorra, Alle 14/1/07 09:49  

  • Doubt does indeed cut both ways, that's the reason of my pieces like this. I have many good reasons to doubt of the good faith of a significant fraction of muslims, but very good reasons to examine each incident on its own merits as well.

    There is a plausible mechanism to explain the false positives obtained in Miami, and no apparent correlation - at least with the information we can obtain - with the previous incident.

    No, middle eastern men are no idiots (without referring to some other members of the LGF community), but neither there is a binary choice between idiots and terrorists.

    Di Blogger Fabio, Alle 14/1/07 22:46  

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